The detection of isotopomers is an important tool but little used to help understand the chemistry of ISM. Indeed, it is possible to demonstrate that a postulated precursor is not valid when its percentage of deuterium or of ¹³C is different: the isotopic effects having little of influence on chemical reactions except when the labeled atom is the reaction center. Hydroxyacetonitrile is related to the aminoacetonitrile detected in 2008 in SgrB2Belloche A.; et al. A&A 482, (2008) 179hich is a potential precursor of the simplest amino acid, glycine, a compound actively sought in ISM because it is considered as the most characteristic building block of the living. In the synthesis of alpha-aminonitriles in the laboratory, hydroxyacetonitriles are common impurities whose proportion is dependent on the initial concentration of ammonia. Hydroxyacetonitrile is also a precursor of aminoacetonitrile by addition of ammonia but it has not been observed to date in the vicinity of the latter. We recorded and published its millimeter spectrumMargules L.; et al. A&A 601, (2017) A50nd the compound was detected a few months later in IRAS16293–2422 BZeng S.; et al. MNRAS 484, (2019) L46 The spectra of both ¹³C and one deuterated isotopomers were recorded in Lille from 150 to 660 GHz. Like the normal species the sample are not commercially available and should be synthesized. The most stable conformer exhibits large amplitude motion due to the two equivalent configurations possible. Due to tunneling effect, each level is split into 0⁺ and 0⁻ substates. This makes the analysis of the spectra delicate. We will report here the very first spectroscopic results obtained and their search in ISM. This project has received financial support from the CNRS through the MITI interdisciplinary programs.

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Belloche A.; et al. A&A 482, (2008) 179w Margules L.; et al. A&A 601, (2017) A50a Zeng S.; et al. MNRAS 484, (2019) L46.

Amidogen (NH₂), an asymmetric-top free radical that belongs to the nitrogen-hydrides family, plays a key intermediate role in the synthesis of interstellar ammonia. While both the main isotopologue and the ¹⁵N-substituted form of amidogen have been detected in the interstellar medium, no astronomical observations of its deuterated variants were reported to date. Recently, we have investigated the rotational spectra of all the deuterated isotopologues of amidogen radical, namely NHD, ND₂, ¹⁵NHD, and ¹⁵ND₂. The measurements have been performed using a frequency-modulation submillimeter spectrometer and a Fourier transform infrared spectrometer that exploits the bright far infrared continuum of the SOLEIL synchrotron, both instruments equipped with discharge sources to produce the radicals. Using improved predictions resulting from the new laboratory studies, NHD and ND₂ have been searched for in the public available Herschel spectral survey of the Class 0 protostar IRAS 16293-2422. Thanks to the observation of several hyperfine transitions between 520 and 790 GHz, we report the first detection of both of these radicals in the interstellar medium. Deuterium fractionation of amidogen will be discussed and compared with astrochemical models.

Experimental and theoretical studies have shown that glycine (NH₂CH₂COOH) and other simple amino acids can be formed in cold astronomical objects of the interstellar medium (ISM). However, the astronomical identification of amino acids in the ISM still represents a great challenge and it is equally important to detect possible precursors of interstellar glycine. Aminoacetonitrile (NH₂CH₂CN), an intermediate product in the Strecker synthesis of glycine, is considered to be one of the most important prebiotic molecules. Recently, aminoacetonitrile has been detected in Sagittarius B2 (Sgr B2) thanks to astronomical observations at millimeter-wavelengths. Motivated by this detection and its astrochemical importance, we have investigated the ro-vibrational spectrum of aminoacetonitrile in the far-infrared region. The measurements have been carried out at the AILES beamline of the synchrotron SOLEIL with a Fourier transform infrared spectrometer. Some low-lying excited states have been detected through the corresponding fundamental bands, whose analysis led to precise vibrational energies. Successively, we have used the new spectral line survey ReMoCA, performed toward Sgr B2(N) with ALMA, to search for NH₂CH₂CN signatures. We detected several tens of rotational lines belonging to the ground and two excited states of aminoacetonitrile. By combining the new laboratory data with the astronomical observations, an accurate value of the column density of aminoacetonitrile could be derived.

Complex organic molecules (COMs) have been detected in a variety of interstellar sources. These sources allow for methods of production linked to increasing temperatures and densities, allowing for thermal chemical reactions to occur rapidly enough to produce observable amounts of COMs, both in the gas phase, and upon dust grains, which then become gaseous as the temperature increases to sublimate the COMs off the grain. As more precursor molecules are detected in colder regions of interstellar space such as cold dark clouds, the same thermal methods of COM production are not efficient enough to produce observable amounts. Radiolysis chemistry is a possible non-thermal method of producing observable amounts of COMs in cold dark clouds. This new method greatly increases the modeled abundance of COMs upon the ice surface and within the ice mantle due to excitation and ionization events from cosmic ray bombardment. We examine three C₂H₄O₂ isomers, and a chemically similar molecule, dimethyl ether (CH₃OCH₃). The modeled abundances of methyl formate (HCOOCH₃) and glycolaldehyde (HCOCH₂OH) should be in the observable range, with fractional abundances of approximately 3.0 ×10⁻¹¹ and 1.3 ×10⁻¹¹, respectively, with respect to hydrogen. Acetic acid (CH₃COOH) is greatly enhanced with the inclusion of radiolysis, with a modeled fractional abundance of 1.375 ×10⁻¹³, but is not at observable abundances. Dimethyl ether, while detected in these regions is not greatly enhanced by radiolysis chemistry, with models with and without radiolysis chemistry show gas-phase fractional abundances of 2.5 ×10⁻¹⁰ and 2.4 ×10⁻¹⁰, respectively.

More than 200 molecules have so far been detected in the interstellar medium (ISM), of which close to one third are complex organic molecules containing six or more atoms. Over the last decades, laboratory experiments simulating the conditions in cold molecular clouds have demonstrated that these COMs can form from interaction of ionizing radiation with simple ices deposited on interstellar dust particles (H₂O, CO, CO₂, CH₃OH, HCO, CH₄, NH₃). These experiments have unveiled multiple pathways towards the formation of acetaldehyde (CH₃CHO) in such ices, explaining its detection in many interstellar and circumstellar environments including tentative detections in interstellar ices. By condensing acetaldehyde and carbon monoxide at 5 K and irradiating the ice with 5 keV electrons, we simulate secondary electrons generated in the trace of galactic cosmic rays interacting with ices around cosmic dust particles. Combined infrared and photoionization reflectron time-of-flight mass spectrometry studies were employed to unambiguously identify pyruvic acid as reaction product from the irradiation by a barrierless radical-radical reaction of the acetyl (CH₃CO) and hydroxycarbonyl (HOCO) radicals. These results present an abiotic pathway towards the formation of this prebiotic molecule in the interstellar medium. As molecular clouds eventually collapse into a star-forming region, molecules formed in the ices can be incorporated into matter in the circumstellar disks, in which planets, planetoids, and comets can form. Fractions of these molecule can survive on their parent bodies to eventually be delivered to planets upon impact, presenting an exogenous source of prebiotic molecules on Earth. Among these, pyruvic acid constitutes a key starting material for the Krebs cycle, which supplies living organisms with energy. Furthermore, it may serve as a prebiotic building block for important biological compounds such as lactic acid or alanine.

To date, nearly 220 individual molecular species, comprised of 19 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. In this talk, I will provide a 30,000 foot view of the demographics of this inventory, the history and lessons learned from where these molecules were first detected, and discuss interesting trends that may help guide future observations. Most importantly, I will identify critical gaps in our knowledge of this inventory, and the areas in which spectroscopic investigations in the laboratory might be most efficiently used to continue driving the ever increasing pace of molecular discovery in the ISM.

The hydroxymethyl (CH₂OH) and methoxy (CH₃O) radicals, products of CH₃OH photodissociation, are considered key reactive intermediates in the interstellar medium (ISM), and their recombination with other fragments is postulated to lead to the formation of commonly observed complex organic molecules (COMs) as glycolaldehyde, ethanol, ethyl glycol, and dimethyl ether. Determination of the CH₃O/CH₂OH ratio should enable to differentiate between gas and grain surface formation scenario for the radicals and therefore for the COMs that form from them. Interestingly, despite the recent first laboratory detection of CH₂OH pure rotational spectrum and while this isomer is the most thermodynamically stable, only CH₃O has so far been detected in the ISM. A plausible explanation to this lack of interstellar detection is the non-observation in the laboratory of the most intense transitions at low temperature. We have re-investigated the pure rotational spectrum of CH₂OH at room temperature in the millimeter-wave domain, using a frequency modulation submillimeter spectrometer, with emphasized searches for the fundamental b-type transitions and those intense at low temperature. The radical was produced by H abstraction from CH₃OH using F atoms produced by a microwave discharge. A combined fit of the infrared and millimeter-wave lines from the literature and our new measurements using a rigid-rotor Hamiltonian yielded a large improvement in the spectroscopic parameters values allowing now confident searches of CH₂OH in cold interstellar environments.

Dimethyl ether and other complex organic molecules are found at higher concentrations in a variety of cold interstellar sources than can be explained by current production mechanisms in chemical models. With the use of microcanonical phase space theory, the radiative association rate coefficient between the methyl and methoxy radical to form dimethyl ether is found to be on the order of 10⁻¹⁰ cm³ s⁻¹ at temperatures relevant to the cold interstellar medium (ISM). This is nearly equal to the collisional rate, which can be on the same order of magnitude, for these two radicals, indicating that neutral radical radiative association is likely in the ISM and should be included in chemical models. These radicals are rare enough that the high rate coefficient still cannot account for all the production of dimethyl ether, but as chemical models continue to evolve to include new processes, and as the radicals themselves are found in new interstellar environments, radiative association should be considered. This example is particularly interesting because there is a bimolecular exit route (the production of formaldehyde and methane), which competes with the association route and dominates at high temperatures.

The knowledge of synthetic routes of complex organic molecules is still far to be fully understood. The creation of reliable models is particularly challenging. Hollis et al.Hollis, J. M.; et al., 2006, ApJ 642, 933ointed out that the observations of molecular isomers provides an excellent tool to evaluate the hypothesis of the synthetic pathways. Formamide (HC(O)NH₂) is an abundant molecule in ISM detected in 1971 in SgrB2Rubin, R. H. ; et al., 1971, ApJ 169, L39 Since formaldoxime and nitrosomethane are two isomers of formamide, they are interesting ISM targets. Up to now the spectroscopic studies are only available up to 40 GHzKaushik V. K. ; et al., 1978, J. Phys. Soc. Jap. 45, 1975Turner P. H. et al., 1978, J. Chem. Soc., Faraday Trans. 2 74, 533. We reinvestigated the spectra of both isomers in the submillimeterwave domain in order to provide more accurate prediction to permit their possible detection in ISM. These two molecules are not commercially available and shoud be synthesized. The spectra were recorded in Lille from 150 to 660 GHz. In the region below 500 GHz we used the new Fourier transform millimeter-wave (FTmmW) spectrometer system based on DDS particulary suitable for unstable speciesZou L.; et al., 2019, 74^th ISMS, Champaign USA FB04 Both analysis are not obvious, formaldoxime has a small dipole moment value: 0.2 Debye, giving weak transitions in the observed spectra. Concerning nitrosomethane, the methyl top internal rotation should be taken into account, therefore the analysis is performed using the version of RAM36 coded which includes the treatment of the nuclear quadrupole hyperfine structureIlyushin, V.V. et al, 2010, J. Mol. Spectrosc. 259, 26 The first spectroscopic results will be presented. This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI.

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Hollis, J. M.; et al., 2006, ApJ 642, 933p Rubin, R. H. ; et al., 1971, ApJ 169, L39. Kaushik V. K. ; et al., 1978, J. Phys. Soc. Jap. 45, 1975

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Zou L.; et al., 2019, 74^th ISMS, Champaign USA FB04. Ilyushin, V.V. et al, 2010, J. Mol. Spectrosc. 259, 26.

This work targets laboratory studies of the Zeeman effects in selected transitions of the FeH radical, observed in the atmospheres of dwarf stars. The F← X electronic system falls around 1 μm, and matches observation windows of the high-resolution spectropolarimeters SPIRou (brought into service in 2019) and ESPaDOnS mounted at the Canada-France-Hawaii Telescope. Many field-free line positions have already been reported for this radical from laboratory studies, notably from high-temperature sourcesLine intensities and molecular opacities of the FeH F⁴∆_i← X ⁴∆_i transition; Dulick et al; Astrophys. J., 594, 651-63, (2003)The near-Infrared Spectrum of the FeH Molecule; Phillips et al; Astrophys. J. Supp. Ser., 65, 721-78, (1987). Our earlier work with a sputter sourceDetermination of Landé factors in the F ⁴∆_{\frac52,\frac72} state of FeH by laser excitation spectroscopy; Crozet et al.; J. Mol. Spectrosc., 303, 46-53, (2014)ielded information on magnetic response for just a few transitions between the two lowest spin components of the F and X states. We report here some preliminary results obtained from FeH formed in reaction between hydrogen atoms (generated in a microwave discharge of H₂ in argon) and traces of iron pentacarbonyl vapour, at pressures around 1 Torr. This sourceDetection of the free radicals FeH, CoH and NiH by far IR laser magnetic resonance; Beaton et al.; J. Chem. Phys. 89, 4446-48, (1988)eems to produce more population in the X ⁴∆_3/2 and X ⁴∆_1/2 components of the ground state. Laser excitation of [1-0] transitions, with lock-in detection of fluorescence in the [1-1] band to eliminate laser scatter, has allowed some Zeeman-broadened profiles to be measured. Line intensities and molecular opacities of the FeH F⁴∆_i← X ⁴∆_i transition; Dulick et al; Astrophys. J., 594, 651-63, (2003)

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Determination of Landé factors in the F ⁴∆_{\frac52,\frac72} state of FeH by laser excitation spectroscopy; Crozet et al.; J. Mol. Spectrosc., 303, 46-53, (2014)y Detection of the free radicals FeH, CoH and NiH by far IR laser magnetic resonance; Beaton et al.; J. Chem. Phys. 89, 4446-48, (1988)s