AE-368 UDC 541:1S 061:3(485)

Scandinavian Meeting Studsvik and Stockholm, September 17-19, 1969

H. Christensen, Editor

AKTIEBOLAGET ATOMENERGI STUDSVIK, NYKOPING, SWEDEN 1969

AE-368

SCANDINAVIAN MEETING STUDSVIK AND STOCKHOLM, SEPTEMBER 17-19, 1969'

ABSTRACTS The report contains the abstracts of papers, which are intended for presentation at the meeting. The complete papers will not be published collectively. The following subjects .are discussed in the abstracts: Pulse radiolysis, water and aqueous solutions including vapour, inorganic systems, organic systems, monomers and polymers and biochemical sys­ tems.

Printed and distributed in August 1 969. - 2 -

LIST OF CONTENTS Page Authors ' Index 3

Pulse radiolysis 4

Water and aqueous solutions 1 8

Inorganic systems 24

Organic systems 27 Monomers and polymers 28 Biochemical systems 31 3 -

Auth ors'Index P age

Andersen, L-O 31, 32 Andersen, T 20 Andersson, U 21 Autio, Timo 30 Bellquist, B 14 Christensen, H C 4, 5, 11 , 12 Cserép, G 13 Edlund, Ove 24 Ehrenberg, A 35 Eriksen, Jytte 15 Fricke, H 19 Friis, Nils 29 Genske, Preben 15 Gillbro, Tomas 28 Gräslund, A 35 Carlson, F • 21 Kasche, Volker 34 Kinell, P-O 27, 31 Kops, Jørgen 29 Lund, Anders 26 Nielsen, S O 4, 5, 11 , 12 Nilsson, Gösta 4, 5, 12 Nilsson, Robert 7 Olsen, K J 20 Pagsberg, P 4, 5, 9, 12 Pedersen, Kai O 31 Reitberger, T 13, 14, 17 Rupprecht, A 35 Said, F 5 Sehested, K 19 Singer, Klaus 29 Stenström, T 22 Ström, G 35 S^r ensen, G 20 Thomsen, P V 20 Österdahl, Bengt 18 - 4 -

ABSORPTION SPECTRA OF HYDROGEN ATOMS, HYDROXYL RADICALS AND SOLVATED IN AQUEOUS SOLUTION FROM 200 TO 250 nm

S O Nielsen', P Pagsberg , H C Christensen' ' and G Nilsson' *) Danish Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark ' AB Atomenergi, Studsvik, Nykoping, Sweden

It has been shown that in aqueous solutions hydrogen atoms, H, and hydroxyl radicals, OH, exhibit a previously unnoticed absorption band 1 2 with an absorption maximum below 200 nm ' . A similar absorption band was recently observed in the far- absorption spectrum, of - 3 2 4 the hydrated , e . Present techniques ' do not allow accu­ rate measurements to be made below 200 nm. At this wavelength all three species show molar absorptivities of comparable magnitude which suggests that the optical transitions involved in the three cases are sim- 1 2 3 ilar in nature. It has been proposed ' ' that the enhanced absorptivity of H, OH and e aq in aqueoux s solution at about 200 nm is due to a red shift of the water absorption beginning at ~ 1 86 nm. This shift is as­ cribed to perturbation of the first excited singlet state of "neighboring" water which involves a partial electron transfer to H, OH and e aq , respectively. This model will be described in detail,

References 1 . Nielsen S O et al. , Pulse radiolytic determination of the ultraviolet absorption of hydrogen atoms in aqueous solution. Chem. Commun. (1968)1523.

2. Pagsberg P et al. , Far-ultraviolet spectra of hydrogen and hydroxyl radicals from pulse radiolysis of aqueous solutions. Direct measurement of the rate of H + H. J. Phys. Chem. 73 (1969) 1029. 3. Nielsen S O et al. , Absorption spectrum of the hydrated electron from 200-250 nm. J. Phys. Chem. 1969. 4. Christensen H C et al. , Pulse radiolysis apparatus for monitoring at 2000 A. Rev. Sci. Instr. 40 (1969)786. - 5 -

DIRECT SPECTROPHOTOMETRIC MEASUREMENT OF THE RATE OF H + OH IN AQUEOUS SOLUTIONS

F Said ', P Pagsberg ^ S O Nielsen*', H C Christensen ' and G Nilsson ' *)' Danish Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark ' AB Atomenergi, Studsvik, Nykoping, Sweden

_3 Pulse radiolytic studies involving 10 M HC1 0. + 0.027 M H2 [P(H_) = 35 atm. J have revealed the existence of a transient species with a second order decay the amplitude of which diminishes monotonically 1 2 from 2000 to 2400 A ' . There is sound experimental evidence for as­ signing these transients to H atoms. This is contrary to the earlier assumption that solutions of free hydrogen atoms in water do not absorb in the far ultraviolet spectral region (> 2000 A). If the absorption spectrum of free hydrogen atoms is assumed to be known, direct measurement of the rate constants 2k.r, „, 2.\a , ^TT and Jrl + rl Orl + UJri ^H + DM becomes possible by means of pulse radiolysis of deaerated so­ 3 lution of 1 0" M HC1 04. Results to date indicate that the measured optical transients from

2000-2600 A due to H, OH and H?0? can be approximated within the ex­ perimental error, by computer calculated transients based on the yields

and extinction coefficients of H, OH and H70? together with previously

found values of 2kTT , TT = (1 . 55 + 0. 1 0) x 1 0' ^ M" sec and 2.\ Z The rate constant ku ^„ was used as the only variable parameter rl + OH to fit the computer calculated transients to the measured transients. The value thus obtained for k„ _„ in the region 2 000-2600 A was found H + OH i . to be somewhat smaller than 1 0 M sec Details are given of the experimental procedure employed and the results obtained together with results obtained in the computer calcula­ tions . - 6 -

References 1 . Pagsberg P et al, , Far-ultraviolet spectra of hydrogen and hydroxyl radicals from pulse radiolysis of aqueous solutions. Direct measurement of the rate of H + H. J. Phys. Chem. 73 (1969) 1029. 2. Nielsen S O et al. , Pulse radiolytic determination of the ultraviolet absorption of hydrogen atoms in aqueous solution. Chem. Commun. (1968)1523. - 7 -

PULSE RADIOLYTIC STUDIES OF THE O' ION-

Robert Nils son Division of Radiobiology, Institute of Biochemistry, Royal University of Stockholm, Stockholm, Sweden

The formation of O" has been postulated in a number of biologi­ cal oxidations which occur under physiological conditions. Although this radical has been directly identified in certain inorganic sys­ tems, direct and conclusive evidence for its formation in most enzymic systems is lacking. Recently, Knowles et al. were able to identify an intermediate by means of ESR using the "rapid freezing" technique developed by Bray . By combining this rapid freezing with

ESR and pulse radiolytic techniques the identity of the 0? radical could definitely be established. Our results provided confirmation that the en- zymically generated radical and the long-lived "alkaline stabilized form of 0?" described by Czapski and Dorfman are identical and correspond, moreover, to 0? itself. Using pulse radiolysis of alkaline aqueous solu­ tions in a flow system provided with facilities for rapid mixing after irradiation, tetranitromethane was found to act as an efficient scavenger 3 for Oy. Czapski and Dorfman showed that the optical absorption at 250 nm was appreciably increased in the presence of methanol. We have found that this increase in absorption is accompanied by an increase in the strength of the ESR signal, demonstrating that the yield of 0? is in­ creased in the presence of the alcohol. It is well established that the reduction of cytochrome c occurs in the presence of xanthine oxidase, substrate and oxygen 4 ' 5 . It has been proposed that 07 serves as the reducing agent in this system. The radio- lytic work of Rabani and Stein gives indication for the occurence of such a process. To study this reaction, 0? was generated by pulse radiolysis both in the presence and in the absence of cytochrome c, following which the kinetics of decay were analyzed. The results of this study and their implications are discussed. - 8 -

References 1 . Knowles P. F. et al. , Electron-spin-resonance evidence for enzymic reduction of oxygen to a free radical, the superoxide ion. Biochem. J. 1 11 (1969) 53.

2. Bray R. C. , Sudden freezing as a technique for the study of rapid reactions. Biochem. J. 81 (1961) 189. 3. Czapski G. and Dorfman L. M. , Pulse radiolysis studies. 5. Transient spectra and rate constants in oxygenated aqueous solutions. J. Phys. Chem. 68 (1964) 1169. 4. Horecker B. L. and Heppel L. A. , Reduction of cytochrome c by xanthine oxidase. J. Biol. Chem. 178 (1949) 683. 5. McCord J. M. and Fridovich I. , Reduction of cytochrome c by milk xanthine oxidase. J. Biol. Chem. 243 (1968) 5753. 6. Rabani J. and Stein G. , The radiation chemistry of aqueous solutions of cytochrome c. Radiation Res. 17 (1962) 327. - 9 -

PULSE RADIOLYSIS OF AMMONIA IN AQUEOUS SOLUTIONS IN THE PRESENCE OF NITROUSOXIDE*

P B Pagsberg Danish. Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark

7 -1 • Ammonia reacts with OH radicals with a rate constant k = 7xl0 M s the OH band thereby being replaced by a new band at 525 nm, which is assigned to the NH? radical. It has an extinction coefficient of 7 5M~ cm" at 525 nm. The yields of the products, NH?OH and N?H. were studied as a function of ammonia concentration. G(N?H.) increases steadily whereas G(NH?OH) passes through a maximum and a minimum with in­ creasing ammonia concentration, indicating the presence of at least two different NH?OH-producing reactions. The maximum yields obtained at high ammonia concentrations were 2(GNH?OH) = 0. 93 - 0. 05 and G(N?H.) =

= 2.23 + 0. 07. G(NH2OH) + G(N2H4) =£(G(e" ) + G(OH) ) + G(H2Oz). The

525 nm band decays with a second order rate constant 2k(NH?) = 3. 5 x 9-1-1 x 10 M s . From the changes in half- in the presence of H?0? 7 1 and O k(NH2 + H202) = 2.2 x 10 M" s"' and k(NH2 + Oz) = 2.2 x x 1 0 M s . .The following set of reactions accounts for the yields of

NH2OH and N2H4-

7 _1 1 (1) NH3 + OH = NH2 + HzO (k = 7.0 x 10 M s" )

(2) NH2 + OH = NH2OH

9 ] ] (3) NH2 + NH2 = N2H4 (2k = 3. 5 x 1 0 M" s" )

7 -1 ] (4) NH2 + H2Oz = NH2OH + OH (k = 2. 2 x 1 0 M S~ ) Reaction (2) takes place only at low ammonia concentrations where the half- of OH has not yet become too small. The rate of this reaction is not accurately known but is roughly estimated to be of the order of 10 M s The chain reaction (4) coupled with (1) is believed to main­ tain a nearly stationary NH? concentration as long as H?0? is present.

Since, however, G(NH~OH) is greater than G(H?0?) at high ammonia

Based on work performed under the auspices of the U.S. Atomic Energy Commission and the Danish Atomic Energy Commission. - 10 -

concentrations where (2) becomes inefficient, the NH radical formed by

(5) NH2 + NH2 = NH + NH followed by (6) NH + H20 = NH2OH was thought of as a possible precursor of the excess yield. Propylene was used as a possible NH scavenger giving propyleneimine. This product has, however, not been isolated and identified so far. - 11 -

PULSE RADIOLYSIS OF AQUEOUS SOLUTIONS OF ANILINE

H C Christensen ' and S O Nielsen ' *)' AB Atomenergi, Studsvik, Nykoping, Sweden **) ' Danish Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark

The primary transient species formed by the irradiation of aqueous solutions of aniline have been studied by pulse radiolysis . The concen- -3 -4 tration of aniline was varied in the range 10 - 10 M and the dose in a single pulse was varied between 600 and 1 5000 rad. Spectra of the transients formed in N^O saturated solutions are demonstrated. In acid solution (pH = 3) the spectrum has a maximum at 41 5 nm, whereas in neutral solution the maximum is located at 3 55 nm. The transients, which are believed to be the addition complexes formed with OH radical, 9 -1 -1 are produced with a rate constant of 6. 6 • 1 0 M • s in both acid and neutral solutions. The transient which is formed in acid, argon-saturated, solutions containing aniline and methanol in the ratio 1 :100, has its maximum at 9 -1 -1 31 5 nm and is formed with a rate constant of 1 . 3 • 1 0 M • s .In view of the high rate constant this transient is believed to be the addi­ tion complex of an H atom with the nucleous. The value of G(H?) in acid, argon saturated, aniline solutions corroborate this assumption. The kinetics of the decay of the transients, which are fairly involved, will be discussed briefly. Reference 1 . Christensen H C et al. , Pulse radiolysis apparatus for monitoring at 2000 A. Rev. Sci. Instr. 40 (1969) 786. - 12 -

PULSE RADIOLYSIS OF D20-ICE

*) *) Gosta Nilsson ', H C Christensen ', P Pagsberg"'' ' and S O Nielsen"'' ' ' AB Atomenergi, Studsvik, Nykoping, Sweden '" ' Danish Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark

Pulse radiolytic techniques have been used to study the trapped elec­ tron in D?0-ice in the temperature range -6 to -172 C. The absorption spectra, the yields and the kinetics of the decay of the trapped electron have been recorded at several temperatures. The data obtained are dis­ cussed and compared to similar data for the trapped electron in H?0- ice. Attempts have been made to fit the kinetic data to different kinetic models with the aid of a computer. - 13 -

RADIATION CHEMISTRY OF METHYLCYCLOHEXENE ISOMERS

G Cserep and T Reitberger Royal Institute of Technology, Stockholm, Sweden

A preliminary study of the fragmentation of methylcyclohexene iso­ mers using Co Y-radiation was made in cooperation with G Cserep, an IAEA-fellow from Budapest. G-values of light hydrocarbon products were determined by analyzing gaseous yields on a gasburette-Toepler- pump combination the various components being identified by gas chro­ matography. The main fragmentation seems to take the form of a "retro Diels-Alder reaction" with a favoured fission of a-bonds in the position |3 to the double bond. Irradiations were carried out with the isomers in liquid and solid (vitreous) state. The general pattern of reaction did not alter with the state of aggregation of the isomer. As a continuation of the work on methylcyclohexane and isomers of methylcyclohexenes an investigation by pulse radiolysis was started. In pure methylcyclohexane a transient is observed which absorbs in the uv-region (^ max. 244 nm) and decays in accordance with second order kinetics. This transient is presumed to be the methyl- cyclohexanyl radical. In 1-methylcyclohexene a transient is observed which exhibits a progressively increasing absorption between 3 50 nm and 300 nm. No peak in the absorption spectrum has so far been ob­ served due to the limited transmission of light trough the pure liquid at wavelenghts < 300 nm. The transient decays in accordance with second order kinetics and may be the allylic methylcyclohexanyl radical. Fur­ ther investigations are in progress at various temperatures and with the addition of ionic and radical scavengers. - 14 -

PULSE RADIOLYSIS STUDIES ON PRIMARY REACTIONS IN SULFOXIDATION OF ALIFATIC HYDROCARBONS

B Bellquist and T Reitberger Royal Institute of Technology, Stockholm, Sweden

In order to obtain deeper insight into the reaction mechanisms in­ volved in the oxidation of alifatic hydrocarbons a pulse radiolytic study of the system cyclohexane, sulfur dioxide and oxygen was initiated. In mixtures comprising cyclohexane and sulfur dioxide a transient at 395 nm is observed. The growth of this transient during and after the pulse is related to the disappearance of the cyclohexylradical at ~ 250 nm "and the consumption of sulfur dioxide as followed at 290 nm. The transient most probably corresponds to the sulfinic acid radical. It decays in accord­ ance with second order kinetics. Addition of air to the system leads to the disappearance of the transient within a few microseconds. Further work is in progress. - 15 -

OPTICAL AND ELECTRONIC TECHNIQUES FOR MONITORING PULSE RADIOLYSIS IN THE FAR-ULTRAVIOLET

Jytte Eriksen and Preben Genske Danish Atomic Energy Commission Research. Establishment RisS, Roskilde, Denmark

A pulse radiolytic apparatus delivering single 0.25 - 4 |Jbsec pulses with a peak current of 250 mA has been developed adjacent to the Ris^ 1 1 MeV linear accelerator. The features of the apparatus include (1) an analyzing light source comprising a 450 W xenon lamp with a 25 times increased luminance during pulsed operation, (2) and optical system, consisting of lenses and cells made of Suprasil quartz, together with vacuum-evaporated alumi­ nium mirrors, and a double, quartz-prism monochromator, (3) a fast electronic switch, which protects the oscilloscopes during the period of Cerenkov radiation. A description will be included of the method of making mirrors with a reflectivity of 90-92% at 2000 A using vacuum evaporated aluminium protected by a layer of. magnesiumfluoride. After repeated irradiations in the accelerator the cells become coloured leading to a reduction in the transmission of analyzing light. The original transmission can be restored by baking the quartz equip­ ment for 3 hours in an oven at 450 C. Before the start of the experiment, great care is taken to center the light in the and to focus the light beam on the entrance slit of the monochromator. This is accomplished by varying the positions of the xenon light source, the mirrors and the lenses. Continuous monitoring of the light illuminating the photomultiplier ensures that an optimum amount of light reaches the photomultiplier. A cell with Suprasil windows, able to withstand the 3 5 atm. of pressure used when the effect of radiation is studied under an atmosphere of hydrogen, will aLso be described. Present work involves the assembling of electronic equipment at the new 2 MeV Febetron field emission accelerator which features a peak - 16 -

current of 4000 amp. A brief description will be given of the 3-nanosec channel for direct continuous monitoring.

Reference

Christensen H C et al. , Pulse radiolysis apparatus for monitoring at 2000 A. Rev. Sci. Instr. 40 (1969) 7 86. - 17 -

A KINETIC SPECTROPHOTOMETER FOR PULSE RADIOLYSIS ADAPTED TO A 7 MeV MICROTRON

T Reitberger Royal Institute of Technology, Stockholm, Sweden

The instrument described is a kinetic spectrophotometer which is used to study fast chemical reactions generated by short pulses of elec­ tron radiation from a 7 MeV microtron. The accelerator produces -2 squarish pulses of 5 • 10 - 5 |i s at peak currents ^ 200 mA. The en- A E ergy constancy of the electron beam is very high (-^r- ^ ' %) owing to the energy focussing property of the microtron. Transient species, characterized by optical absorption in the wavelength region 200-800 nm, are detected. The sensivity in the visible part of spectrum is high enough to reproduce small transients which decay within a few micro­ seconds after the pulse. The electronic system is of an unconventional design and offers ease of operation, fast response and flexibility. With a few improvements it should be possible to adapt the system for opera­ tion with pulsed light sources. Pulse radiolysis has been carried out with this instrument since december 1 968. Only preliminary results are at present available. - 18 -

THE RADIOLYSIS OF METHYLMERCURY IN AQUEOUS SOLUTIONS

Bengt Osterdahl Royal Institute of Technology, Stockholm, Sweden

The methylmercury ion, CH_Hg , forms two hydroxycomplexes in water:

+ 9, 37 CH3Hg + OH" <—» CH3HgOH k = 1 0 (1 )

CH Hg+ + CH HgOH

The dominant form at a given pH can be calculated from the known stability constants. Thus:

PH dominant form

+ - 4.0 CH3Hg

5. 5 - 11.0 CH3HgOH

+ 2. 0 - (CH3Hg)2OH

Accordingly studies of the radiolysis of the carbon-mercury bond in solutions at different pH-values permits interpretation of the effect of complexing. Preliminary experiments of this type indicate that reaction (1 ) exerts a marked effect. Thus at pH < 4. 0 a G(-CH Hg ) of about 4. 0 is found, while at 5. 0 < pH < 7. 0 G(-CH Hg+) is about 3.0. The solutions were irradiated in a Co Y-cell at a dose rate of 450 krad/h. The investigation is to be extended to higher pH-values, and the system methylmercury-water will be studied by pulse-radiolysis. This can give valuable information as to the type of attack which is relevent and indicate the nature of the intermediate species. - 19 -

60 Co Y-RAY RADIOLYSIS OF AQUEOUS SOLUTIONS OF JL, + Oz

DETERMINATION OF G - + G„ AT pc H 0. 5 - 7 e aq H

K Sehested and H Fricke Danish Atomic Energy Commission Research Establishment Riso, Roskilde, Denmark

Recent determinations of the primary yield in the aqueous system in­

dicate that the previously reported value of 3. 2 for G(H~0?) in Y-irradiated

neutral solutions of H? + 0? is too low. A similar G (peroxide) of 3. 2 for the CLLCH-OH + O-, system was recently explained by Bielski and Allen as being due to an inhibitory effect of the reaction product CrLCHO. The

present work shows that when the H? + 0? system is irradiated under

conditions appropriate to the scavenging of all the free radicals, G(H?0?) = = 3.66; this is in good agreement with recent values for the primary yields. In view of the simplicity of the reactions involved, this system affords an excellent means of determining the reducing radicals. From the reaction mechanism the G-values of the reducing radicals can be ex­ pressed as

Ge_ + GR = G(H2Oz) - G aq c

The standard conditions were 1 50 pM 02 +7 00 y.M H2 at pH's 0. 5-7

irradiated with dose rates at 0. 8 and 0. 08 rad/sec. The H?09 was deter- mined by reactions with Fe II and the dose curve is linear up to 3-4 (j,M

H~,0~2 2, where the back reaction e~a q + H20 002 starts. To avoid the reaction OH + "H02" —> H203 —> HzO + O-, a fairly low dose rate must be used since "HO," accumulates. The G - is found to be constant over the pH- 2 e aq range from 3-7, G - =2. 66. With decrease of pH the G - progres- S 6 aq m aq sively increases. For comparison purposes G(Fe ) has been measured in deaerated 1 mM FeSO. and a very good agreement between the two systems was found. - 20 -

RADIOLYSIS OF WATER VAPOUR BY LOW-ENERGY HEAVY IONS

T Andersen, K J Olsen, G Sj^rensen and P V Thomsen Institute of Chemistry and Institute of Physics, University of Aarhus, Aarhus, Denmark

_4 The radiolysis of water vapour at low pressure (=s 1 0 torr) has been studied using ion beams from an electromagnetic isotope separator and a 600 keV ion accelerator. The ions used were He , Ne , Ar , K , Kr and Xe at energies of 30, 60 and 500 keV. Radiolytic products were investigated both directly in the gas phase by means of emission spec­ troscopy and indirectly using ESR and chemical analysis of the deposits formed by condensing the irradiated vapours. The species H, OH, O and OH were detected in the gas phase. Hydroxyl radicals were present in deposits formed at temperatures at or below -180 C. Hydroperoxy radicals were present in all investigated deposits, but no electrons could be detected. Relative and absolute cross sections for the generation of hydroxyl radicals with 60 keV inert gas ions were measured and are compared with theoretical calculations for the reaction Ion + H?0-» OH + + H. - 21 -

DECOMPOSITION OF STEAM BY REACTOR RADIATION

F Carlson and U Andersson AB Atomenergi, Studsvik, Nykoping, Sweden

Some preliminary investigations have been made in the steam-cooled loop in the R2 reactor at Studsvik on the decompositions of steam during its passage through the in-pile section and of the influence of various pa­ rameters on this decomposition. The following experimental conditions have been used: - steam pressure 45-80 bar - steam temperature 3.60-525 C - irradiation time 0. 02-0. 09 sec - reactor power 5-30 MW, (30 Mf corresponds to a deposition of radiation energy for neutrons and gamma radiation of 0. 49 • 10 1 3 1 3

and 1.78- 10 MeV/g H?0* sec, respectively)

- concentrations of H? and O., in the steam at the entrance of the in-pile section of the loop have generally been less than 0. 1 and

0. 05 ml (STP)/kg H?0 (except when additions of H? or 0? have intentionally been made to the steam) The experiments have shown that under the prevailing conditions the decomposition of steam is proportional to reactor power. Furthermore the decomposition increases with rise of temperature and decreases with rise of pressure. Calculation of the G-value for the decomposition indicates that G(-H?0) depends upon the specific volume of the steam and increases as the specific volume increases. For the prevailing experimental COn- ditions namely a specific volume of steam of 30-70 dm /kg, the value of

G(-H O) is in the range 1 . 5-7 molecules of H?0 for each 1 00 eV unit of radiation energy deposited in water.

Additions of H? or 0? to the steam previous to its entry into the in- pile section have been shown to suppress the steam decomposition. The suppression increases with increasing additions of K? or 0? up to the maximum addition of about 3 0 ml (STP)/kg H?0. - 22 -

1 1C- AND 13N- LABELLED COMPOUNDS PRODUCED BY IRRADIATION OF WATER AND DILUTE AQUEOUS SOLUTIONS WITH 185 MEV PROTONS

Tore Stenstrom

The Gustaf Werner Institute, University of Uppsala, and Department of Radiobiology, The Agricultural College of Sweden Uppsala, Sweden

When water is irradiated with 185 MeV protons, C (T,/-, = 20. 4 min), 13 15 ' N (T, /_ = 10.0 min) and O (T. /_ = 2 min) are produced from oxygen-1 6 by nuclear reactions. In an earlier work it was shown, that macromolecules such as inulin, dextran and insulin by irradiation of dilute aqueous solutions 11 11 could be labelled with C in good yields (up to 50 % of the total C activity produced, as determined by gel filtration). The labelling mechanism is, however, unknown. With the intention to elucidate the reactions of hot C atoms in aqueous solutions "pure" (triply distilled) water and low molecular solutions were irradiated with relatively low doses. The products were analysed by gas chromatography, selective absorbtion of gases and ion exchange. The aldehyde was precipitated as the 2. 4-dinitrophenylhydrazone. CO_, 11 CO, HnCOOH, H]1CHO, ^CH.OH, and ' ' CH . were found as products 11 in all cases. The yield of CO? increased with the dose relative to other products. The addition of a number of different OH radical scavengers to the water before the irradiation gave fairly similar results with CO, H COOH, and H CHO as the dominating products relatively independent of the scavenger used. The results are discussed in terms of possible hot and thermal reactions leading to "primary" molecular products, and secondary reactions between these compounds and the water radicals. Of special interest is the primary reactions of the hot or thermalized C atom with the -water and the water radicals. Radical scavengers present in the solution during irradiation may protect "primary" products from radiolysis but may also have an effect on the yields of these products if they are produced in reactions with primary water radicals. The yields of the "primary" C labelled products in per cent of the total - 23 -

C yield were estimated to be C02 > 5 %, CO < 45 %, H COOH < < 35 %, HnCHO < 30 %, ] 'CHOH < 10 %, and 1 ] CH < 0.5 %. 11 In another experiment C-labelled derivates were obtained when higher alcoholes were irradiated in dilute aqueous solution. The prod­ ucts were analysed by gas chromatography. - 24 -

STUDY OF RADIATION-INDUCED FREE RADICALS IN INORGANIC COMPOUNDS CONTAINING HYDROGEN BONDS

Ove Edlund The Swedish Research Councils ' Laboratory Studsvik, S-61 1 01 Nykoping 1, Sweden

Single crystals of inorganic substances containing hydrogen bonds

(N2H6(H2P04)2, N2H5HC204, NaHC204 • r^O, NaDC204 • D20) have been Y-irradiated at room temperature. The trapped radicals produced have been identified by the ESR-method.

It was possible to observe (N?H4) -ion and CO?" - -(2H)-ion as trapped radicals in N^Ht-C^O. and NaHC^O. • H?0 respectively. A change in the orientation of the (N?H4) -ion was detected, but within the limits of experimental accuracy it was not possible to observe any change in the orientation of the CO?~--(2H)-ion. This report is mainly concerned with results for NaHC204 • H20. The crystal was rotated about three perpendicular axes and spectra were recorded at 1 0 degree intervals. The signal consisted of a single line for several orientations. In other special directions it was also possible to detect a splitting due to hydrogen bonded hydrogens; this was confirmed by an experiment with the deuterated substance NaDC?0 . • D?0, for which no splitting could be observed. 1 3 In every spectra the g-value and C -splitting were measured. From the angular dependence of these quantities for each rotation axis it was possible to calculate the principal values of the tensors of the g-value (g) and C -splitting (A) {g = 0 . 997 0; 2. 0032; 2. 0016); A = (151, 156, 196)G}

The results are in good agreement with these for the CO? -ion deter­ mined in earlier studies. The transformation matrix between the coor­ dinate system consisting of the three axes mentioned above and the crys- tallographic axes give the direction cosines for the principal values and consequently the orientation of the radical. - 25 -

The probable reaction is:

HC2O4" ^JC-^ c2o4" + H -» co2 + co2"

in the irradiated substances where the radicals are identified the unit cell contains one whereas (N?H,) (H.PO,)-, for example has two molecules in the unit cell with different orientations. This means that the two radicals which are produced give two overlapping spectra which leads to difficulties of interpretation. - 26 -

THE STRUCTURE AND REACTIVITY OF PARAMAGNETIC CENTERS IN Y-IRRADIATED SILICA GEL

Anders Lund The Swedish Research Councils ' Laboratory, Studsvik, S-611 01 Nykoping 1, Sweden

Irradiation of silica gel at 77 K yields paramagnetic hole centers probably trapped at nonbridging oxygen atoms. Holes also become trapped at oxygen sites associated with impurity aluminium ions. At . 01 mW microwave power the intensity of an absorption at g = 2. 0008 which is attributed to trapped electrons, is 3 0% of the total signal strength but saturates at higher powers. The centers react with oxygen and hydrogen at 77 K during the course of several months storage. At 300 K the reaction with oxygen is complete within 3 0 min and 0? radical ions are formed. Carbon dioxide traps electrons which are liberated in the silica gel while the hole sig­ nal is unaffected. The behaviour with other electron scavengers such as oxygen and nitrous oxide is more complicated. The absence of hole signals and the detection of hydrocarbon cations when aromatic com­ pounds are present is interpreted in terms of a trapping of holes at the adsorbed molecules. The formation of radicals by the additon of hydro­ gen atoms, released from irradiated surface hydroxyl groups, is dis­ cussed. Alternative interpretations are reviewed. - 27 -

AN ESR STUDY OF CATION RADICALS FOUND BY Y-IRRADIATION OF AROMATIC HYDROCARBON/SILICA GEL SYSTEMS

Per-Olof KineLl The Swedish Research Councils " Laboratory, Studsvik, S-611 01 Nykoping 1, Sweden

In binary, heterogeneous systems consisting of a solid silica gel phase and an adsorbed aromatic hydrocarbon phase evidence has been found for the formation of monomeric and dimeric radical cations. The silica gel had a specific surface of 667 m /g (BET) and had been heat- treated at 500 C in a high vacuum for several hours. The hydrocarbons were adsorbed at low temperature onto the surface to various degrees of coverage. Irradiation with Y-rays from Co was next performed at 77 K to a total dose of 1 -3 Mrad at a dose rate of about 300 krad/h. The radi­ cals formed were then studied by ESR technique using the X-band. Spectra were recorded at various temperatures from 77 K upwards. In the case of benzene the central part of the system can be resolved into a seven line pattern whith a line separation of 4. 4 G, which indicates the formation of a monomeric cation radical. At increased coverages new lines appear between the lines of original pattern and finally a thir­ teen line spectrum with a line separation of 2. 2 G is obtained. This in­ dicates the formation of a dimeric cation radical. Similar observations have been made on naphthalene, anthracene, phenanthrene and biphenyl. In the case of benzene the yields of the cation radicals have been meas­ ured as a function of dose and of degree of coverage. Hiickel molecular-orbital calculations have shown that a sandwich type of dimeric cation radical is stable by comparison with an isolated neutral molecule and a cation radical. Furthermore, the trimer, tetra- mer etc. are also stable but to a lesser degree, having regard to the number of aromatic rings involved. Spin-density values, based on the atomic orbital coefficients in the molecular orbitals occupied by the old electron, are in accordance with the experimentally observed line splitt­ ings. The results obtained indicate that during the irradiation process the silica gel has an oxidising effect on the hydrocarbons; energy is trans­ ferred from the gel to the adsorbed phase. - 28 -

INVESTIGATIONS ON SOME VINYLMONOMERS IN THE CRYSTALLINE STATE

Tomas Gillbro AB Atomenergi, Studsvik, Nykoping, Sweden

The experiments have largely been concerned with the problem of manufacturing single crystals of the vinylmonomers, methylmethacrylate (MMA) and methylacrylate (MA), for ESR measurements. To obtain good crystals it was necessary to impose a slow rate of growth at a con­ stant temperature not far below the melting point. For this purpose a device has been constructed which can maintain a constant temperature (AT < 1 C) in the cooling bath in the interval 0-150 C. The crystals were grown with a velocity of about 0. 5 to 3. 0 mm/h. The ESR spectra of single crystal MMA and MA demonstrated formation of radical pairs under Y-irradiation. ESR spectral evidence for the formation of radical pairs comprised a large anisotropic splitting with a maximum of about 250 G and another hyperfine splitting of 1 1 G. This is half the hyperfine splitt­ ing found in a single radical of the type CH- - CH - R. In view of the complexity of the spectra it is essential to know the orientation and the structure of the crystals. Accordingly a low-temperature structure de­ termination has been started. The space group of MMA has been found to be either monoclinic C2 or C2c, the unit cell dimensions and angle being& a o =14. 4 A, b o =6.3A,c o = 14.8 A and 0 = 1 27° with 8 molecules per unit cell. MA crystallises with orthorhombic cell, space group Pnma, cell dimensions a o = 12. 53 A, b o = 6. 25 A and c o = 5.90 A with 4 molecules of monomer per unit cell. - 29 -

RADIATION-INITIATED EMULSION POLYMERIZATION OF VINYL ACETATE

Nils Friis ', Jprgen Kops ' and Klaus Singer ' *)7 Institutet for Kemiindustri, Technical University of Denmark *#) ' Chemistry Department Danish Atomic Energy Commission Research Establishment, Riso, Roskilde, Denmark

The radiation initiated emulsion polymerization of vinyl acetate has been studied by comparing the kinetics of the reaction induced by Y irra­ diation and that induced by chemical means. The reaction rate was meas­ ured by dilatometry. The chemical initiator used in these experiments

was (NH4)?S?OR and the radiation source was a 1000-curie Co source. The overall activation energy for radiative initiation was found to be about -4 kcal/mole, while the overall activation energy for chemical initiation was approximately 8 kcal/mole. The rate of the chemically induced reaction is directly proportional to the initiator concentration while the rate of reaction resulting from Y irradiation is approximately proportional to I * , where I equals the dose rate. A simultaneous doubling in the concentration of monomer and emul- sifier does not change the rate of the chemically induced reaction (quoted as per cent converted per min) whereas the rate of the y-induced reac­ tion (expressed in the same units) is decreased to half of the original value. The average molecular weight, M , determined by viscosity meas- A h v urements is about 10 -1.6x10 in the case of the products of Y irra- 5 5 diation and about 2x10 -4x10 for the products of chemical initia­ tion. The nonionic-emulsifier phenoxypoly(ethylenoxy)ethanol (Antarox CO 970) used in these experiments made it possible to prepare poly- vinylacetate emulsions with a high content of dry matter, at best about 45%. - 30 -

CURING OF MIXTURES OF UNSATURATED POLYESTERS AND STYRENE WITH

Timo Autio Institute of radiochemistry, University of Helsingfors, Helsingfors, Finland

The application of Co Y -irradiation for the curing of unsaturated polyester-styrene mixtures (PE-S) has been studied. The dose necessary for the curing depends on the composition of the polyester, the content of styrene and most decisively on the temperature of curing: For a mix­ ture containing 55% styrene the necessary dose at a dose rate of 100 krad/h is 2 Mrad at 60 C and 1 0 Mrad at 30 C; at 0 C the polymerization remains uncomplete. By using after-curing it is possible to continue the polymerization owing to the effect of radicals trapped in the polymer. In the investigated PE-S polymers the content of gel and solvent and the residual content of styrene has been determined as a function of the irra­ diation dose, curing temperature and composition. In addition the second order transition point of the polymers, i. e. the influence of the bonds on the curing properties, has been studied. - 31 -

RADIOLYSIS STUDIES ON SERUM ALBUMIN

*) #) *# Kai O Pedersen , L-O Andersson ' and P-O Kinell *)' University of Uppsala, Uppsala, Sweden ' The Swedish Research Councils ' Laboratory, Studsvik, S-611 01 Nykoping 1, Sweden

Aqueous solutions of bovine serum albumin have been subjected to gamma irradiation under various experimental conditions. In addition to polymerisation the irradiation also produces splitting of the albumin molecule. The irradiated solutions have been fractionated on Sephadex columns, and the amount of the different components formed has been determined. Many of the fractions have been studied chemically and in the ultracentrifuge. It was thus found that when the irradiations were carried out in moderately concentrated albumin solutions, the new com­ ponents formed demonstrated sedimentation diagrams of greater defini­ tion than those of diluted albumin solutions irradiated to give the same relative decrease in the monomer concentration. The effect, measured from the decrease in the albumin monomer, depends on the pH of the solution, being most pronounced at about pH 6. A series of experiments was carried out in which albumin solutions were saturated with various gases. The radiation effects were consid­ erably enhanced by the presence of argon and still more by N?0. The effect of the dose has been studied for several albumin con­ centrations, and the effect of dose rate is under investigation. - 32 -

COUPLING OF DYES AND ENZYMES TO GEL MATRIXES BY MEANS OF Y-IRRADIATION

L-O Anders son University of Uppsala, Uppsala, Sweden

It was recently reported (Nature 222 (1 969) 374) that dyes could be coupled to various macromolecules by means of gamma-irradiation of aqueous solutions of the macromolecule and the dye. The mechansim suggested for the coupling is as follows:

(1) RH + X - R + HX (2) DH + X -» D + HX (3) DH+R-D + HR (4) R +D-DR The macromolecule (RH) reacts with some radical X from the water and a macromolecular radical R is formed. This can then react with a dye radical (D) which has been formed according to (2) or (3) and the adduct DR is obtained (4). Reaction (3) is also a repair process from which protection against is obtained. To study the possibility of coupling substances to gel matrixes by means of irradiation, experiments were performed in which various gels were irradiated in the presence of a dye. Coupling was demonstrated by the irradiation with 1 Mrad of Co gamma-irradiation of swollen Sep- hadex G 1 50 gel in 0. 02 M phosfate buffer pH 8. 0 (1 mM with respect to fluorescein).: the gel remained strongly coloured even after extensive washing. Further experiments showed that it was possible to couple dyes such as methylene blue and bilirubin to agarose gels. Experiments aimed at coupling enzymes to gel matrixes were then tried. On irradiating 1 5 ml of Sepharose 4 B gel containing 1 5 mg of pepsin in 0. 1 M acetate buffer pH 3. 8 with 1 Mrad, amino acid analysis of a portion of the washed gel indicated that 13. 5% of the enzyme was coupled to the gel. The amino acid analysis also showed that considerable destruction of the cystine, methionine and tyrosine residues had occured. The activity of the coupled enzyme was 8% of that of the native enzyme - 33 -

as determined by the hydrolysis rate of hemoglobin. In another experi­ ment trypsin was coupled to Sephadex G 1 50 gel. The yield of coupled enzyme was 1 . 8% and its activity was 1 0% of that of the native enzyme. The results obtained indicate that coupling by irradiation can be used in many different systems. Its main drawback is that it is impos­ sible to avoid radiation damage to the components of the system. - 34 -

RADIOCHEMICAL PRODUCTION OF ] ] C-LABELLED a-CHYMOTRYPSIN AND SEPARATION OF ENZYMATICALLY ACTIVE LABELLED ENZYME BY MEANS OF SPECIFIC ADSORBENTS

Volker Kasche Dept. of Radiobiology, The Gustaf Werner Institute, University of Uppsala, P.O. Box 531 , 751 21 Uppsala 1, Sweden

Protein molecules with induced changes in activity and conformation can be separated from unperturbed molecules in separations based on differences in activity, by means of specific adsorbents. This method has been used in a study of the direct and indirect radi­ ation inactivation of or -chymotrypsin (CT). In its active state the enzyme interacts specifically with soybean trypsin inhibitor (STl), a competitive inhibitor with pK. ~7 at pH 7, STI covalently linked to a gel matrix (Sepharose) was therefore used as a specific adsorbent for CT. All ra­ diation products had activities less than a , the activity of native CT. Most of the initial products had esterase and protease activities in the range, 0.7 a -1.0a. They account for more than 50% of the initial change in total activity of the enzyme sample. All of these products have undergone chemical modification by interaction with intermediate radi­ cals. These protein radicals can combine with other radicals produced 11 13 by radiation. In proton irradiations of aqueous solutions C and N are produced and are incorporated in unstable low-molecular weight ra­ dicals. These radicals can combine with protein radicals. Thus we can 11 13 obtain enzymatic ally active CT labelled with C and N. They are separated from inactivated enzyme molecules in separations with spec­ ific adsorbents. The results obtained demonstrate that in deoxygenated 11 13 solutions 20-30% of the induced C and N-activity is incorporated in the enzymatically active CT-fraction. In the presence of oxygen the amount incorporated is less, indicating that the label is introduced in radical-radical reactions. 1 ] ] 3 C (T1 /2 = 20 min, Eg = 0.38 MeV) and N (T] >z = 1 0 min,

ER = 0.48 MeV) are suitable isotopes for in vivo experiments. This method of producing labelled molecules with retained biological activi­ ty can therefore be applied in physiological tracer studies with proteins in vivo. - 35 -

Y -IRRADIATED ORIENTED DNA STUDIED BY ELECTRON SPIN RESONANCE

A Graslund, A Rupprecht, G Strom and A Ehrenberg Department of Biophysics, Stockholm University, Stockholm, Sweden c/o Department of Biochemistry, Karolinska Institutet, and Bacteriological Bioengineering, Department of Bacteriology, Karolinska Institutet, 1 04 01 Stockholm 60, Sweden

We have studied the free radicals whose formation is induced by y- irradiation in DNA at 77 K. These radicals are precursors to the well- known hydrogen addition radicals on the thymine base, which in our samples are formed in about 50% yield after annealing to 1 96 K. Before freezing and irradiation the samples were equilibrated over

H?0 or D?0 to 66% relative humidity. Orientation of the samples was achieved by a special wet-spinning technique (1 ). ESR measurements were made on a Varian V-4500 spectrometer with a modified microwave bridge, permitting measurements at microwave power sufficiently low, < 3 (j,W, to avoid saturation in the samples. The ESR spectra exhibit anisotropy, both in signal amplitude, g- value, and resolution, depending on the relative orientation of the helix axis in the samples to the magnetic field of the spectrometer (2). From the symmetries of the ESR spectra one can deduce that the unpaired electrons are probably associated with the TT-electron system of the bases. A closer analysis of the features of the spectra and their temperature dependence shows that one major type of free radical may predominate. Its hyperfine structure is generally smeared out, however, except in a few per cent of the radicals. These few per cent give a sharp hyperfine structure (linewidth 2 G), which indicates coupling of the unpaired elec­ trons to two unexchangeable hydrogen atoms and one nitrogen atom. Suggested explanations of these effects will be discussed. - 36 -

References 1 a. Rupprecht A, Preparation of oriented deoxyribonucleic acid in large amounts. Biochem. Biophys. Res. Commun. 12 (1963) 163. lb. Rupprecht A, Preparation of oriented DNA by wet spinning. Acta Chem. Scand. 20 (1 966) 494. 2. Ehrenberg A, Rupprecht A and Strom G, Electron spin resonance of gamma-irradiated oriented DNA prepared by wet spinning. Science 1 57 (1967) 1317.

LIST OF PUBLISHED AE-REPORTS 335. Solution of large systems of linear equations in the presence of errors. A constructive criticism of the least squares method. By K. Nygaard. 1968. 28 p. Sw. cr. 10:-. 1—290. (See the back cover earlier reports.) 336. Calculation of void volume fraction in the subcooled and quality boiling regions. By S. Z. Rouhani and E. Axelsson. 1968. 26 p. Sw. cr. 10:-. 291. Separlaion of "Cr by means of the Szilard-Chalmers effect from potassium 337. Neutron elastic scattering cross sections of iron and zinc in the energy chromate irradiated at low temperature. By D. Brune. 1967. 15 p. Sw. region 2.5 to 8.1 MeV. By B. Holmqvist, S. G. Johansson, A. Kiss, G. Lo- cr. 10:-. din and T. Wiedling. 1968. 30 p. Sw. cr. 10:-. 292. Total and differential efficiencies for a circular detector viewing a circu­ 338. Calibration experiments with a DISA hot-wire anemometer. By B. Kjell- lar radiator of finite thickness. By A. Lauber and B. Tollander. 1967. 45 p. strom and S. Hedberg. 1968. 112 p. Sw. cr. 10:-. Sw. cr. 10:-. 339. Silicon diode dosimeter for fast neutrons. By L. Svansson, P. Swedberg, 293. Absolute M1 and E2 transition probabilities in >"U By S. G. Malmskog and C-O. Widell and M. Wik. 1968. 42 p. Sw. cr. 10.-. M. Hojeberg. 1967. 37 p. Sw. cr. 10:-. 340. Phase diagrams of some sodium and potassium salts in light and heavy 294. Cerenkov detectors for fission product monitoring En reactor coolant water. water. By K. E. Holmberg. 1968 48 p. Sw. cr. 10:-. By O. Strindehag. 1967. 56 p. Sw. cr. 10:-. 341. Nonlinear dynamic model of power plants with single-phase coolant reac­ 295. RPC calculations for K-forbidden transitions in 1"W. Evidence for large tors. By H. Vollmer. 1968. 26 p. Sw. cr. 10:-. inertial parameter connected with high-lying rotational bands. By S. G. 342. Report on the personnel dosimetry at AB Atomenergi during 1967. By J. Malmskog and S. Wahlborn. 1967. 25 p. Sw. cr. 10:-. Carlsson and T. Wahlberg. 1968. 10 p. Sw. cr. 10:-. 296. An investigation of trace elements in marine and lacustrine deposits by 343. Friction factors in rough rod bundles estimated from experiments in parti­ means of a neutron activation method. By O. LandstrSm, K. Samsahl and ally rough annuli — effects of dissimilarities in the shear stress and tur­ C-G. Wenner. 1967. 40 p. Sw. cr. 10:-. bulence distributions. By B. Kjellstrtim. 1968. 22 p. Sw. cr. 10:-. 297. Natural circulation with boiling. By R. P. Mathlsen. 1967. 58 p. Sw. cr. 10:-. 344. A study of the resonance interaction effect between J"U and 1J'Pu In the 298. Irradiation effects at 160-240°C in some Swedish pressure vessel steels. lower energy region. By H. Haggblom. 1968. 48 p. Sw. cr. 10:—. By M. Grounes, H. P. Myers and N-E. Hannerz. 1967. 36 p. Sw. cr. 10:—. 345. Application of the microwave discharge modification of the Wilzbach tech­ 299. The measurement of epithermal-to-thermal U-238 neutron capture rate (p2e) nique for the tritium labelling of some organics of biological interest. By in Agesta power reactor fuel. By G. Bernander. 1967. 42 p. Sw. cr. 10:-. T. Gosztonyi. 1968. 12 p. Sw. cr. 10:-. 300. Levels and transition rates In '"Au. By S. G. Malmskog, A. Bicklin and B 346. A comparison between effective cross section calculations using the inter­ Fogelberg. 1967. 48 p. Sw. cr. 10:-. mediate resonance approximation and more exact methods. By H. Hagg­ blom. 1969. 64 p. Sw. cr. 10:-. 301. The present status of the half-life measuring equipment and techniaue at Studsvik. By S. G. Malmskog. 1967. 26 p. Sw. cr. 10:-. 347. A parameter study of large fast reactor nuclear explosion accidents. By J. R. Wiesel. 1969. 34 p. Sw. cr. 10:-. 302. Determination of oxygen in aluminum by means of 14 MeV neutrons with an account of flux attenuation in the sample. By D. Brune and K. Jirlow. 348. Computer program for inelastic neutron scattering by an anharmonic crystal. 1967. 16 p. Sw. cr. 10:-. By L. Bohlin, I. Ebbsjo and T. Hogberg. 1969. 52 p. Sw. cr. 10:-. 1,! 303. Neutron elastic scattering cross sections of the elements Ni, Co, and Cu 349. On low energy levels in W. By S. G. Malmskog, M. Hojeberg and V. between 1.5 and 8.0 mev. By B. Holmqvist and T. Wiedling. 1967. 17 p. Berg. 1969. 18 p. Sw. cr. 10:-. Sw. cr. 10:-. 350. Formation of negative metal ions in a field-free plasma. By E. Larsson. 304. A study of the energy dependence of the Th232 capture cross section In 1969. 32 p. Sw. cr. 10:-. the energy region O.I to 3.4 eV. By G. Lundgren. 1967. 25 p. Sw. cr. 10:-. 351. A 'determination of the 2 200 m/s absorption cross section and resonance 305. Studies of the reactivity effect of polythene In the fast reactor FRO. By L. integral of arsenic by pile oscillator technique. By E. K. Sokolowski and R. I. Tiren and R. Hakansson. 1967. 25 p. Sw. cr. 10:-. Biadh. 1969. 14 p. Sw. cr. 10:-. 306. Final report on IFA-10, the first Swedish Instrumented fuel assembly Irra­ 352. The decay of "

EOS-tryckerierna, Stockholm 1969