THE CHEF11 CAL EFFECTS OF NUCLEAR TRANSFORMATIONS IN SOUE TELLURIUM COMPOUNDS JOHN LAWRENCE WARREN B.Sc. University of Washington, 1966 A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of CHEMISTRY @ JOHN LAWRENCE WARREN, 1970 SIMON FRASER UNIVERSITY November, 1970 EXAMINING COMMITTEE APPROVAL Professor C.H.W. Jones Department of Chemistry ............ Simon Fraser University Research Supervisor Dr. G. Harbottle ./. .w ....-. ..-. .I.. ........... Brookhaven National Laboratory External Examiner Professor B.D. Pate .., ................-......... Department of Chemistry (, Simon Fraser University Examining Committee Professor L.K. Peterson Department of Chemistry . ,f .-.w C-rusr ..-.........--a-. .w ~4 Simon Fraser University Examining Committee Professor D.J. Huntley Department of Physics _-.l~.LJ....~.ic..-........./.. 2Lt , - Simon Fraser University - Examining Committee Name: JOHN LAWRENCE WARREN Degree : DOCTOR OF PHILOSOFHY Title of Thesis: CHEMICAL EFFECTS OF L~UCLEARTRANSFOREWTIONS IN SOME TELLURIUM COMPOUNDS a Date Approved: 30 'F~WCJA~~C~ ABSTRACT The chemical effects of several different nuclear transformations were studied in solid tellurium compounds using both standard radiochemical techniques and ~sssbauer spectroscopy with 129~. In the radiochemical investigation, a comparative study was made in telluric acid, H6Te06, of the molecular - fragmentation accompanying the 130Te (n,y) 131Te +6- 1311 process and the ~--deca~of 13lmTe , 131~e,and 132~e. The chemistry of 12'Te recoil atoms formed in the 128~e(n,y) 12'Te nuclear reaction and the decay of 129m~ein telluric acid were also investigated. In each instance the thermal annealing reactions of the recoil fragments in the solid were investigated. The study of the radioactive decay of 13lmTe - , l3l~e-,132~e-, and 129m~e-labelled samples was of particular importance. These isotopes differ in the degrees of electronic excitation and ionisation accompanying their decay. Thus it was of interest to see if such differences would lead to different patterns of molecular fragmentation or to differences in the subsequent annealing reactions of 1321 the recoil fragments. It was found that the 13'1 and recoil atoms formed in the decay of the first three isotopes - - were present in the same chemical forms I , 103 , and 104 ) but in differing yields. Differences were also observed in iii the thermal annealing reactions in these samples, which may be interpreted in terms of the different processes accompanying the decays. It was found that the 12'~e atoms born in the isomeric transition decay of 129mTe are similar in their annealing behaviour to the 132~atoms born in the decay of 132~e. Both of these decay processes are accompanied by large degrees of internal conversion of y-transitions, which leads to qualitatively similar annealing reactions of the daughter recoil atoms. The trends observed in the recoil product distributions and the annealing reactions are discussed in terms of the difference in the nuclear trans- formations producing the recoil atoms. The ~ossbauerexperiments allowed the study of the recoil atoms in situ in the solid and thus provided a much more detailed picture of the chemical effects of the nuclear transformations. The chemical effects of the decay of 6' 6' 129Te -+ 12'1 were studied in telluric acid, (H2Te04),, a-Te03, tetragonal Te02, and H2Te03 using the 27.7 keV,16.8 nanosecond M6ssbauer transition in 12'1 to provide information about the chemical form of the iodine atom produced. These experiments were performed with a standard absorber and with the source and absorber at liquid nitrogen or liquid helium temperatures. No chemical effects of the 6--decay were observed in any of the above compounds, the iodine atom remaining bonded to the ligands of the precursor tellurium molecules. These results are in sharp contrast to the findings of the radiochemical experiments. Studies were made of the 129mTe -+ 12'~e isomeric transition in 129m~e-labelledcompounds using the 12gI ~ossbauerspectrum to provide information about the chemical form of the 12'Te atoms formed in the decay. Molecular fragmentation was observed to accompany the decay in a considerable fraction of events in f6Te0 and (H2Te04). with 6 2- the formation of the TeOj ion as the sole decomposition product. The 12 8, ~e(n,y)l~~Tenuclear reaction was found to produce the same decomposition in H TeO 6 6' The thermal annealing reactions of the isomeric transition and (n,y) recoil atoms were also studied and found to lead to a simple, single-step reactinn, TeOj2- -+ Te(V1). In addition to the above, the ~ossbauerwork provided several pieces of information concerning bonding and structure in these tellurium compounds and allowed the determination 129= of several constants of general interest in 12'Te and ~ossbauerstudies. The results of the Xossbauer work are compared and contrasted with those of the radiochemical study. TABLE OF CONTENTS CHAPTER PAGE 11. A REVIEW OF THE CHEMICAL EFFECTS ASSOCIATED WITH NUCLEAR TRANSFORMATIONS ......... A. Sources of Recoil ~ineticEnergy and ~lectronic Excitation in Nuclear Transformation Processes .................. 6 1. Thermal Neutron Capture ......... 6 Isomeric Transition 3. Negative Beta Decay .......... 13 B. Models of Recoil Energy Loss Processes in Solids ................... 17 C. Annealing Reactions ............. 22 1. Nechanisms of Annealing Reactions .... 22 2. The Role of Crystal Defects in Recoil Fragment Annealing ............ 25 3. Kinetic Analysis of Recoil Fragment Annealing ............. 2 8 4. Conclusions .............. 30 111. DECAY CHARACTERISTICS FOR THE TELLURIUM- IODINE SYSTEMS INVESTIGATED IN THIS WORK..................... 31 A. Decay Sequences Studied in the Chemical Analysis of Iodine Recoil Atoms ....... 35 B. Decay Sequences Studies in the Chemical Analysis of Tellurium Recoil Atoms ..... 38 vi CHAPTER PAGE IV . PREVIOUS RADIOCHEMICAL IKVESTIGATIONS OF IODINE AND TELLURIUM RECOIL FRAGMENTS IN SOLIDS .................... 40 A . Iodine Recoil Atoms Produced in Tellurium Compounds ............. 40 B . Iodine Recoil Atoms Produced in Iodine Compounds ............... 42 C . Tellurium Recoil Atoms Produced in Tellurium Compounds .................. 43 .. V . THE MOSSBAUER EFFECT ........... 49 A . Basic Principles ............... 49 B . Chemical Applications of ~gssbauer Spectroscopy ................ 53 1 . The Isomer Shift ............. 54 2 . Quadrupole Splitting ........... 56 12gI 59 VI . THE M~SSBAUEREFFECT FOR ........ A . Choice of Mgssbauer Nucleus .......... 59 B . Nuclear Transformations Available for Study With 129~ .................. 63 C . Analysis of the ~6ssbauerEffect With 12'1 in Iodine Compounds ............... 65 1 . Analysis of Isomer Shift Data ....... 66 2 . Analysis of Quadrupole Splitting Data ................... 71 VII . PREVIOUS APPLICATIONS OF M~SSBAUERSPECTROSCOPY TO THE STUDY OF CHEMICAL EFFECTS ....... 74 A . Studies with ~gssbauerNuclei Other than Tellurium and Iodine ............. 74 1 . 57~e ................... 75 2 . l19sn ................... 77 3 . Other Systems ............... 78 vii CHAPTER PAGE B. Studies With Isotopes of Tellurium and Iodine . 2. 127~and 12gI .............. VIII. EXPERIMENTAL TECHNIQUES . A. General Preparation of Telluric Acid . B. Sample Preparations for the Chemical Investigation of Iodine Recoil Atoms In Telluric Acid . 1. H6Te06 for Thermal Neutron Irradiation . 2. HgTe06 Pre ared Labelled With 130~e and 131RTe . 3. HgTe06 Prepared Labelled Specifically With 13*~e .............. C. Sample Preparations for the Investigation of Tellurium Recoil Atoms in Telluric Acid . 1. HgTe06 for Thermal Neutron Activation . 2. HgTe06 Prepared Labelled With 129mTe for Studies of Chemical Effects of Isomeric Transition . D. Chemical Separations and Analysis of Recoil Fragments . 1. Analysis for the Oxidation States of 1311 . 2. Chemical Analysis for the Oxidation States of1321 . 3. Analysis for Te (IV) and Te (VI) in Telluric Acid . E. General Counting Procedures . viii CHAPTER PAGE F . Annealing Investigations .......... G . Mgssbauer Spectrometer Systems ~mployed . 12gI H . Mgssbauer Experiments With ...... 1 . General Methods ............. 2 . Source Activities for 12'1 Massbauer Emission Experiments .......... 3 . Preparation and Mounting of ~Gssbauer Sources ................. 104 I . Tellurium Compounds Prepared as Massbauer Sources .................. 105 3 Na TeO K2Te0 106 . 2 4' ............. 4.a-Te03 ................. 106 11.ZnTe .................. 111 J . ~6ssbauerExperiments Xith 125~e...... 111 K . Computer Analysis of MGssbauer Spectra .................. 115 ix CHAPTER PAGE IX. RESULTS AND DISCUSSION OF CHEMICAL INVESTIGATIONS OF IODINE AND TELLURIUM RECOIL SPECIES IN TELLURIC ACID . 117 Experimental Results for Studies of Iodine Recoil Atoms . 117 1. Initial Distributions of Recoil Products................. 117 2. Thermal Annealing of Recoil Atoms . 122 3. The Role of Crystal Defects in the Thermal Annealing Reaction . 125 4. Thermal Annealing of 13*1 Recoil Products . 130 Experimental Results for Studies of Tellurium Recoil Atoms . 132 Discussion of Radiochemical Results . 139 131mTe- 1. 13'~e- 132?e-1 and 129mTe Labelled Samples . 140 2. Neutron Irradiated Samples . 146 Introduction . 149 12'~e-labelled Sources . 151 1. 12'~e-labelled ~ellurium (VI)compounds . 151 2. 129~e-~abelledTellurium (IV)compounds . 157 3. Elemental Tellurium . 160 129m~e-~abelledSources and Neutron Irradiated Sources . 165 1.