SUBMILLIMETERWAVE SPECTROSCOPY AND ISM SEARCH FOR PROPIONIC ACID

L. Margulès1, R. A. Motiyenko1, V.V. Ilyushin2, O. Dorovskaya2, E.A. Alekseev2, E. R. Alonso3, L. Kolesniková3, J. Cernicharo4, and J.C. Guillemin5

1Laboratoire PhLAM UMR8523,Université de Lille, France 2Institute of Radio Astronomy of NASU, Kharkiv, Ukraine 3Lab. de Espectroscopica y Bioespectroscopica, Universidad de Valladolid, Spain 4Molecular Astrophysics, ICMM, Madrid, Spain 5Institut des Sciences Chimiques de Rennes, ENSCR, France

L. Margulès et al, 74TH International Symposium on Molecular Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS C3H6O2 isomers

Relative energy

kj.mol-1 cm-1 propanoic acid 0.00 0.00 methyl acetate (ISM) 29.20 2440.56 ethyl formate (ISM) 48.86 4083.98 lactaledehyde 106.32 8887.84 metoxy acetaldehyde 151.31 12648.32

Ethenoxymethanol 157.65 13178.79

1,3 diooxolane 2 159.24 13311.79 C3H6O2 isomers in ISM • Ethyl formate EtOC(O)H

• Methyl acetate CH3OC(O)CH3

L. Margulès et al, 74TH International Symposium on Molecular 3 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Previous studies

• MW Double resonnance up to 40 GHz (O. Stiefvater, J. Chem. Phys. 62, 244, 1975) • FTMW measurements up to 18 GHz (B. Ouyang et al, J. Phys. Chem. A 112, 8208, 2008)

ma= 0.19 D

mb= 1.53 D

mc= 0.00 D -1 V3=810.7(37) cm

Main difficulty is a low vibration bending mode at 35cm-1

L. Margulès et al, 74TH International Symposium on Molecular 4 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Fast DDS Lille’s spectrometer

DDS-based synthesizer allows very fast frequency switching with high resolution and continuous phase

• Fast decade spanning spectrometer:0.15-1.5 THz • Less than 24h is needed at high resolution (Doppler limited) and sensitivity to record the all range • Typical: Acq. time 1ms/point

On going developpment: emission spectroscopy (L. Zou FB04)

L. Margulès et al, 74TH International Symposium on Molecular 5 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Potential function in internal rotation

V3 V6 Methyl group is C3v symmetry : V(a) = (1- cos3a)+ (1- cos6a)+... S 2 2 • Due to tunnel effect, the transitions are splitted into

2 E 1 - 2 A two components: A and E

1 1 A

- 1 E •The code used in these cm

Energy in Energyin cm studies is RAM36-code from 786 786

= = 0 E 3 V. Ilyushin which include V 0 A terms up to 12th order. The code could treat V case, Torsional angle 6 in degree used for toluene study (V. Ilyushin et al. J. Mol. Spectrosc

259, 26, 2010).

L. Margulès et al, 74TH International Symposium on Molecular 6 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Propionic acid results

RAM axis system this work A (GHz) 9.8430(28) B (GHz) 4.0667(26) C (GHz) 2.86781(11) F (GHz) 165.857 (fixed) r 0.05206(14)

1 V3 (cm- ) 786.04(34)

2Dab (GHz) -2643(12)

FMAX 550GHz

Nparam/Nlines 20/2530 Rms/wrms 56 kHz/0.86

L. Margulès et al, 74TH International Symposium on Molecular 7 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS ISM search

• No detection of propionic acid in : . Orion (30m and ALMA) . SgrB2 (public data from Belloche) . SGrB2 PRIMOS) . dark clouds surveys . 30m data of IRAS16923 . 12m NRAO data of W51.

• upper limits and comparaison with the abundances of the other conformers will be given in the future paper

L. Margulès et al, 74TH International Symposium on Molecular 8 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS ISM search

• Why no detection? • Methyl formate is one of the major exception of Minimum Energy principle (Lattelais et al, ApJ, 696, L133, 2009) : adsorption of acid on the grains • Formate could be favored as methyl formate is much more abundant that acetic acid

• The reason could be link to the way CO2 on ice grains hydrogenate and methylate

• methylisation of CO2 is a possible route to form

CH3COOCH3

L. Margulès et al, 74TH International Symposium on Molecular 9 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS From Laboratory to Interstellar medium: « It is a long way to the top »

R.A. Motiyenko, PCCP, 2018,20, 5509 - B. A. Mc Guirre et al. 2018, ApJL, 851, 2

L. Margulès et al, 74TH International Symposium on Molecular 10 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Target’s choice

• Definition of targets follow mainly the 3 following pathways and is based on detected molecules • Going to next complexity • replacing atom (O with S for exemple), groups,… • isomers of detected molecules

L. Margulès et al, 74TH International Symposium on Molecular 11 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS From Laboratory to Interstellar medium: « It is a long way to the top » 1) Target discussions between astronomers, chimists and spectroscopists (yes it is sure, it will be detected in ISM….) 2) Sample availibility (not fun if this is commercialy available, why we miss

propylene oxide CH3CHCH2O) 3) Measurements of the spectra (easier with fast spectrometer) 4) Analysis of the spectra : from hours to months…. not only because spectrosocpits are lazy, large amplitude motion make analysis difficult most of the time! (easier with broadband spectrometer) FAST+BRAODBAND : Lille’s fast scan DDS spectrometer 5) Accurate predictions provided: interpolation only, no extrapolation 6) Detection or not... In very few cases detection could be in ISM prior to lab (example : NS+, Cernicharo et al., 2018, ApJL, 853, 2)

L. Margulès et al, 74TH International Symposium on Molecular 12 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Molecules detected « recently » Acetaldehyde-D We report the first detection of CH2DCOH (93 transitions) and the detection of CH3COD (43 transitions) species in IRAS 16293-2422 using the publicly available ALMA PILS

L. Margulès et al, 74TH International Symposium on Molecular 13 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Ethyl cyanide CH3CH2CN isotopologues

Ethyl cyanide, also known as propanenitrile or propionitrile, has been observed in abundance in hot molecular clouds in the range 40–950 GHz (1st ISM detection: Johnson, D. R., et al. 1977, ApJ, 218, 370)

13C detection 15N detection

1st detection of doubly no detection subtitled 13C

-1 -1 Excited vibrational state study (vbending = 206 cm and vtorsion = 213 cm ) of 13C species in collaboration with JPL (B. Drouin‘s group)

L. Margulès et al, 74TH International Symposium on Molecular 14 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Formamide NH2CO - D

• Formamide (HCONH2) is the simplest molecule with a peptide bond detected in the interstellar medium (Rubin, R. H., et al. 1971, ApJ, 169, L39) • it has been shown that of all possible simplest interstellar molecules that contain a peptide bond, formamide is the most stable energetically (Lattelais, et al. 2010, A&A, 519, A30 )

−1 • ν12 = 289 cm . All other excited vibrational states lie above 500 cm−1 • 13C also measured in this work

L. Margulès et al, 74TH International Symposium on Molecular 15 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS N-methylformamide: CH3NHCHO

• structural isomer of the known interstellar molecule acetamide,

CH3C(O)NH2 • Both molecules contain a peptide bond which is the characteristic chemical bond linking amino acids in proteins • N-methylformamide can also be seen as a partially hydrogenated

form of methyl isocyanate, CH3NCO, which was recently detected in the ISM

• Internal rotation motion with very low barrier value: 55.17 cm-1 • The spectra was measured from 45 to 660 GHz • The analysis is carried out using the 16 Rho-axis method and the RAM36 code NS+

L. Margulès et al, 74TH International Symposium on Molecular 17 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Hydroxyacetonitrile (HOCH2CN)

• Compete with aminomethanol (NH2CH2OH), a glycine precursor, through the Strecker synthesis (Danger G. et al., ApJ 756, 11, 2012) • Its photochemistry leads to the formation of formylcyanide (CHOCN),

ketenimine (CH2CNH), formaldehyde (CH2O), hydrogen cyanide (HCN), carbon monoxyde (CO) (Danger G. et al. A&A 549, A93, 2012)

• Detection of aminoacetonitrile in SgrB2(N) (NH2CH2CN) (A. Belloche, et al. A&A, 2008, 482 179)

Methyl isocyanate

(CH3NCO) the most stable energetically structural isomer was detected

BREAKING NEWS detection in IRAS 16293

18 Lot of non detections

Di-cyanomethane (malonitrile-NC-CH2-CN) and isocyanomethane • Following the first microwave study of a bis-isocyanide derivative diisocyanomethane (Motiyenko et al., A&A 2012, 544 A82)

• No MW study about the cyano-isocyanomethane (CNCH2CN). • the most stable isomer malonitrile also reinvistigated: • Study is limited to 240 GHz (Burie et al. 1982, J. Phys. 43, 1319) • Spin statistic we put in evidence in the diisocyanomethane study was not took into account.

Acetyl isocyanate (CH3CONCO)+CH3ONCO • Isocyanic acid, HNCO, was among the very early molecules to be detected in space • OCN- is assumed to be in the grains (K. Demyk et al. A&A, 339 (1998), 553)

• CH3COCH3 is detected since 1987 Sgr B2 (F. Combes et al. A&A, 180, (1987), L13)

• CH3O detected in B1-b (Cernicharo et al. 2012, ApJ, 759, L43) • NCO in L483 (Marcelino et al.,2018, A&A, L10

L. Margulès et al, 74TH International Symposium on Molecular 19 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Ethyl-isocyanide (CH3CH2NC)

• The few isocyanides detected in the ISM are always isomers of the

corresponding : HNC, CH3NC, HCCNC • Isocyanides molecules are poorly studied mainly due Spectroscopy of isocyanides is often complicated by difficulties in synthesis and kinetic instability of many of them

• Ethyl-iscocyanide (CH3CH2NC) is isomer of one of the most abundant Complex Organic Molecules • Very badly surprised with the non detection

L. Margulès et al, 74TH International Symposium on Molecular 20 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Aminomalononitrile : H2NCH(CN)2 • HCN trimer (trimer of the key molecule for 15N fractionation) • AMN is a useful intermediate in the synthesis of many heterocyclic systems. Such properties designate AMN as a key compound in prebiotic chemistry and an attractive candidate for the ISM • The analysis of the rotational spectra of the A conformation has shown that the observed lines exhibit a doublet or quartet structure owing to two large-amplitude motions, C−N torsion and amino group inversion

b conformer 6.7 kJ/mol higher in energy

L. Margulès et al, 74TH International Symposium on Molecular 21 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Propanimine (CH3CH2CHNH) • The aldimines are important to understand amino acids formation process as they appear in reaction scheme of Strecker-type synthesis.

• Methanimine (CH2NH) was detected in 1973 (Godfrey et al., ApJL, 13, 119 1973)

• Beginning of the projet was studying ethanimine (CH3CHNH) in

02/2013. But at the same time it was detected in SgrB2 with Primos survey (Loomis et al., ApJL, 765, L9, 2013) • We decided to study the next one in the serie: propanimine • We used a synthesis method to obtain pure samples. E,Z-Ethanimine and E,Z Propanimine has been prepared in the following way : precursors have been slowly vaporized in a reactor containing dry KOH in powder (50 g) in half section and heated to 85-100°C

Z conf E conf DEa = 264.25 cm-1 m = 1.12 D a L. Margulès et al, ma= 2.49 D mb= 0.75 D m = 1.00 D Manuscript in = 1.57 D b mc preparation mc= 0.00 D

L. Margulès et al, 74TH International Symposium on Molecular 22 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Sulfur compounds

• Twenty moleules detected in ISM are sulfur-bearing chemical compounds (and analogues of oxygenated species) • Sulfur is the tenth most abundant element in the galaxy • Except with NS+, we are unlucky with sulfur compounds

• S-methyl-thioformate - CH3SC(O)H - (Jabri et al., Manuscript in prepraration)

• Thio-acetaldehyde – CH3CHS - (Margulès et al., Manuscript in prepraration) • Propynethial - HCΞC-CHS (Evans et al., Manuscript in prepraration)

L. Margulès et al, 74TH International Symposium on Molecular 23 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS « I only know one thing, I do not know anything » (Platon, Apologie de Socrate)

2 recent studies were particulary important for astrochemistry models:

• The non-detection of CH2OH (Bermudez et al., 2017, A&A, 598)

was a surprise, the upper limit to the column density of CH2OH of

1/1000 that of methanol. CH2OH was supposed to be major precursor of methanol in ISM. • The recent detection of methoxymethanol (B. A. Mc Guirre et al. 2018, ApJL, 851, 2) show it is ∼34 times less abundant than

methanol (CH3OH), and significantly higher than predicted by astrochemical models

L. Margulès et al, 74TH International Symposium on Molecular 24 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Future targets

• We were successfull with excited vibrational states, or isotopologues of « weeds » • Several issues when looking to new molecules • Diificulty to find the right target despite regular discussions with astrophysics groups • One way could be the amines, amino acids, amino alcool…. • laboratory experiments showed that formation of amines and amino acids in the interstellar medium (ISM) is possible • only a few molecules with–NH2 group detected in the ISM only two « amines » • Most of these samples were not commercial, and stable in laboratory conditions • Radicals are involved in COM’s formation pathways. Lot of them not studied in laboratory yet.

L. Margulès et al, 74TH International Symposium on Molecular 25 Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS Aknowledgements

• Action sur Projets de l'INSU : "Physique et Chimie du Milieu Interstellaire"

• Centre National d'Etudes Spatiales (CNES) And many thanks for your attention

L. Margulès et al, 74TH International Symposium on Molecular Spectroscopy, JUNE 17-21, 2019 - CHAMPAIGN-URBANA, ILLINOIS