The sulphur chemistry in space is still quite puzzling although several S-bearing species have been detected in the interstellar medium (ISM) in our local system and outside our galaxy. In particular, we observe very large quantities of sulphur harbouring molecules, especially in high-mass star forming regions, that are in perfect accordance with its solar abundance, while in the cold, dense ISM a much lower abundance is observed compared to its solar one. To have a better understanding of the sulphur chemistry in space, it is crucial to derive the broadest picture of the chemical network involving the formation of sulphur species. In this work we report high-resolution spectra of a simple triatomic S-bearing molecule, the HSO radical, with experiments well into the THz region. Thanks to the spectroscopic results of this work, which provide accurate frequency predictions up to the THz, we have also performed a rigorous search for HSO in space. The main outcomes of our work will be briefly presented, showing in particular the synergy between the laboratory and the observations.

Short carbon chains are fundamental for the chemistry of stellar and interstellar ambiences. The linear carbon chain molecule C₃ has been found in various interstellar and circumstellar environments, encompassing diffuse interstellar clouds, star forming regions, shells of late type stars, as well as cometary tails. Due to the lack of a permanent dipole moment C₃ can only be detected by electronic transitions in the visible spectral range or by vibrational bands in the mid-and far-infrared region. We performed experiments where C₃ was produced via laser-ablation of a graphite rod with a 3 bar He purge and a subsequent adiabatic expansion into a vaccum resulting in a supersonic jet. We report laboratory measurements of the lowest bending mode transitions of six ¹³C-isotopologues of the linear C₃ molecule. Fifty-eight transitions have been measured between 1.8-1.9 THz with an accuracy of better than 1 MHz. Molecular parameters have been derived to give accurate line frequency positions of all ¹³C isotopologues to ease their future interstellar detection. A dedicated observation for singly substituted ¹³CCC is projected within the SOFIA airborne observatory mission.

We will discuss the status of millimeter-wave laboratory measurements of the rotational spectra in the ground and vibrationally excited levels of small molecules containing two or three silicon atoms that might be the building blocks of dust seeds in carbon- and oxygen-rich AGB stars. The motivation is to provide essential spectroscopic information needed to guide future interferometric observations of the inner envelope of these objects at high angular resolution and sensitivity. The focus will be on a half-dozen species for which there is either no prior high resolution spectroscopy, or only in the centimeter band at best. We will also update the status of the known silicon carbides SiCC and SiCSi.

Methoxymethanol (CH₃OCH₂OH), a ten atoms molecule, is a very interesting candidate for the detection in the interstellar medium since it can be formed by the reaction between both possible radicals of methanol: CH₃O (already detected in the ISM) and CH₂OH. It could be also formed by addition of CH₃O on formaldehyde (another detected compound in the ISM) followed by the addition or abstraction of a hydrogen radical. According to quantum chemical calculations, methoxymethanol has three stable conformations: Gg, Gg’, and Tg. The most stable Gg conformation has a small dipole moment of 0.27 D, whereas two others conformations Gg’ and Tg are considerably less stable (8.5 kJ/mol and 10.9 kJ/mol respectively), but have much greater dipole moments (2.47 D and 2.17 D respectively). Thus, in the room-temperature rotational spectra the three conformations may have approximately the same line intensities. We measured the rotational spectrum of methoxymethanol between 150 and 500 GHz and detected all three conformations. The major difficulties in the spectral analysis consist in the very dense spectrum of methoxymethanol and low signal-to-noise ratio of the lines, and in different large amplitude motions. The methyl top internal rotation splittings were observed for the rotational lines of Gg and Gg’ conformations. The doublet structure of Tg conformation rotational lines may be explained by -OH group tunneling between two equivalent gauche configurations. The analysis is in progress, the latest results will be presented. The support of the Äction sur Projets de l'INSU PCMI, and ANR-13-BS05-0008-02 IMOLABS" is gratefully acknowledged

The formation of interstellar methanol and its related chemistry have been topics of much discussion and debate within the astrochemical community. This discussion has now also been extended to include methoxy (CH₃O), a closely-related radical, after its initial discovery within a prestellar core was reported by Cernicharo and coworkers (2012). Using a supersonic expansion of methanol diluted in argon and coupled with a plasma discharge, we have collected the rotational spectrum of methoxy at submillimeter wavelengths. By coupling these results with data from a number of other literature reports, we have prepared an updated line catalog that will greatly enhance opportunities to search for interstellar methoxy. We will present these results in the context of related astrochemical processes.

We have studied methyl cyanide, one of the so-called ‘astronomical weeds’, in the 200-277 GHz band. We have experimentally gathered a set of intensity calibrated, complete, and temperature resolved spectra from across the temperature range of 231-351 K. Using our previously reported method of analysisJ. McMillan, S. Fortman, C. Neese, F. DeLucia, ApJ. 795, 56 (2014) the point by point method, we are capable of generating the complete spectrum at astronomically significant temperatures. Lines, of nontrivial intensity, which were previously not included in the available astrophysical catalogs have been found. Lower state energies and line strengths have been found for a number of lines which are not currently present in the catalogs. The extent to which this may be useful in making assignments will be discussed.

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J. McMillan, S. Fortman, C. Neese, F. DeLucia, ApJ. 795, 56 (2014),

Iso-propyl cyanide, also known as iso-butyronitrile, is a branched alkyl molecule recently detected in the interstellar medium.A. Belloche, R. T. Garrod, H. S. P. Müller, K. M. Menten, Science, 2014, 345, 1584. combination of Stark-modulated microwave spectroscopy and frequency-modulated millimeter and submillimeter wave spectroscopy was used to analyze its rotational spectrum from 26 to 480 GHz. Spectral assignments and analysis include transitions from the ground state, eight excited vibrational states and ¹³C isotopologues. Results of this work should facilitate astronomers further observations of iso-propyl cyanide in the interstellar medium.

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A. Belloche, R. T. Garrod, H. S. P. Müller, K. M. Menten, Science, 2014, 345, 1584.A

Aminomethanol (HOCH₂NH₂) is a molecule of astrochemical interest as it is thought to be the precursor to the simplest amino acid, glycine. To date, no laboratory spectrum has been recorded because it is unstable under normal laboratory conditions. As a result, a millimeter spectrometer was developed to study the products of O(¹D) insertion into methylamine, with the goal of producing aminomethanol. Here we present the results of this study, including other observed reaction products and a preliminary assignment of aminomethanol.

The ability to detect molecules in the interstellar medium (ISM) is afforded to us by the collaboration of state-of-the-art observations, like from the Atacama Large Millimeter/submillimeter Array (ALMA), and high-resolution laboratory spectra. Here, we present our use of a commercial segmented chirped-pulse Fourier transform millimeter-wave rotational spectrometer to study simple oxygen-containing organic molecules. Our spectrometer operates in the region 75 – 110 GHz, providing an overlap with ALMA’s Band 3 and allowing direct comparison of our laboratory spectra with observational data. We have measured rotational spectra of 1,2-propanediol[1, 2, 3] and methyl acetate[4, 5] in this spectral range at room temperature – both have been previously studied in the microwave and millimeter-wave regions. The rotational spectrum of the former in the 3 mm region shows eight different conformers to date. Spectral bandwidth overlap with ALMA Band 3 will allow for easier detection of new chemicals in the ISM.
[1] Caminati, W., J. Mol. Spectrosc., 86(1), 193-201, 1981. [2] Lovas, F. J., Plusquellic, D. F., Pate, B. H., Neill, J. T., Muckle, M. T. and Remijan, A. J., J. Mol. Spectrosc., 257(1), 82-93, 2009. [3] Bossa, J. –B., Ordu, M. H., Müller, H. S. P., Lewen, F. and Schlemmer, S., Astron. Astrophys., 570, A12, 2014. [4] Tudorie, M., Kleiner, I., Hougen, J. T., Melandri, S., Sutikdja, L. W. and Stahl, W., J. Mol. Spectrosc., 269, 211-225, 2011. [5] Nguyen, H. V. L., Kleiner, I., Shipman, S. T., Mae, Y., Hirose, K., Hatanaka, S. and Kobayashi, K., J. Mol. Spectrosc., 299, 17-21, 2014.

Hydantoin (Imidazolidine-2,4-dione, C₃H₄N₂O₂) is one of five-membered rings with heteroatoms and could be synthesized from carbonyl compounds such as aldehydes or ketones via so-called Bucherer-Bergs reaction. This molecule is also known as a direct precursor of amino acid by hydrolysis, evidently, hydantoin has been found in carbonaceous chondrites with several kinds of amino acids. for example, A. Shimoyama and R. Ogasawara, 2008, Orig. Life Evol. Biosph. 32, 165 (2002). The aim of this study is to provide spectroscopic information which is useful for the future astronomical search.The hydantoin vapor was obtained by heating hydantoin powder to 150^

Aminoacetonitrile (NH₂CH₂CN) is a potential precursor of the simplest amino acid, glycine in the interstellar space and was detected toward SgrB2(N). A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, and C. Hieret, 2008, Astronom. & Astrophys. 482, 179 (2008). We have extended measurements up to 1.3 THz so that the strongest transitions that may be found in the terahertz region should be covered. Y. Motoki, Y. Tsunoda, H. Ozeki, and K. Kobayashi, Astrophys. J. Suppl. Ser. 209, 23 (2013). Aminoacetonitrile has a few low-lying vibrational excited statesB. Bak, E. L. Hansen, F. M. Nicolaisen, and O. F. Nielsen, Can. J. Phys. 53, 2183 (1975). and indeed the pure rotational transitions in these vibrational excited states were found.C. Fujita, H. Ozeki, and K. Kobayashi, 70th International Symposium on Molecular Spectroscopy (2015), MH14. The pure rotational transitions in six vibrational excited states in the 80-180 GHz range have been assigned and centrifugal distortion constants up to the sextic terms were determined. Based on spectral intensities and the vibrational information from Bak et al., They were assigned to the 3 low-lying fundamentals, 1 overtone and 2 combination bands. In the submillimeter wavelength region, perturbations were recognized and some of the lines were off by more than a few MHz. At this moment, these perturbed transitions are not included in our analysis.

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A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, and C. Hieret, 2008, Astronom. & Astrophys. 482, 179 (2008).\end Y. Motoki, Y. Tsunoda, H. Ozeki, and K. Kobayashi, Astrophys. J. Suppl. Ser. 209, 23 (2013). B. Bak, E. L. Hansen, F. M. Nicolaisen, and O. F. Nielsen, Can. J. Phys. 53, 2183 (1975).\end C. Fujita, H. Ozeki, and K. Kobayashi, 70th International Symposium on Molecular Spectroscopy (2015), MH14.

Acenaphthene (Ace) is a three ring polycyclic aromatic hydrocarbon (PAH), which consists of naphthalene and a non-aromatic five member ring. Ace has been previously been studied by microwave spectroscopy where the rotational constants were reported[1]. New measurements from 2-8 GHz using chirped pulse-Fourier transform microwave spectroscopy (CP-FTMW) will be presented. The high sensitivity achieved enabled us to observe all ¹³C isotopologues in natural abundance and determine the Kraitchman substitution structure. The spectra of Ace complexed with water and H₂¹⁸O were also recorded at this frequency range. From these spectra, we have been able to assign the complexes Ace-(H₂O)_n, n=1-3 and (Ace)₂-H₂O and experimentally derive the O-atom position of the H₂O. The Ace-(H₂O)₃ complex is especially interesting as the water aggregate forms a slightly distorted cyclic water trimer from that observed in the IR[2]. These complexes could give insight about the formation of ice grains in the interstellar medium.
[1] Thorwirth, S., Theulé, P., Gottlieb, C.A., McCarthy, M.C., Thaddeus, P. Astrophys. J., 662, 1309-1314, 2007. [2] Keutsch, F.N., Cruzan, J.D., Saykally, R.J. Chem. Rev., 103, 2533-2577, 2003.

The simplest tricyclic aromatic nitrogen heterocyclic molecules 5,6 benzoquinoline and 7,8 benzoquinoline are possible candidates for detection of aromatic systems in the interstellar medium. Therefore the pure rotational spectra have been recorded using frequency-scanned Stark modulated, jet-cooled millimetre wave absorption spectroscopy (48-87 GHz) and Fourier Transform Microwave (FT MW) spectroscopy (2-26 GHz) of a supersonic rotationally cold molecular jet. Guided by ab initio molecular orbital predictions, spectral analysis of mm wave spectra, and higher resolution FT MW spectroscopy provided accurate rotational and centrifugal distortion constants together with 14N nuclear quadrupole coupling constants for both species. The determined inertial defects, along with those of similar species are used to develop an empirical formula for calculation of inertial defects of aromatic ring systems. The predictive ability of the formula is shown to be excellent for planar species with a number of pronounced out of plane vibrations. The resultant constants are of sufficient accuracy to be used in potential astrophysical searches.We gratefully acknowledge support from the Deutsche Forschungsgemeinschaft, the Deutsche Akademische Austauschdienst, as well as the Land Niedersachsen (J.-U.G). DMcN also thanks the Royal Society of Chemistry for their generous travel support.html:<hr /><h3>Footnotes: We gratefully acknowledge support from the Deutsche Forschungsgemeinschaft, the Deutsche Akademische Austauschdienst, as well as the Land Niedersachsen (J.-U.G). DMcN also thanks the Royal Society of Chemistry for their generous travel support.

Two efforts have been underway to enable the laboratory study of cosmic analogs dusts in the frequency range 60-2000 GHz. They are: (1) the construction of a novel compact Fourier Transform Spectrometer (FTS) design coupled to a dry 4-K cryostat which houses a cooled sample exchanger (filter wheel) and a bolometer. (2) The production of Mg- and Fe-rich silicate dusts using sol-gel methods; various tests to determine their physical and chemical properties; embedding of samples in LDPE pellets for insertion into the novel FTS. This presentation will focus on the current status of the apparatus and data from its first few months of use.

Icy grain reactions have gained quite the popularity in the astrochemistry community to explain the formation of complex organic molecules. Through temperature programmed desorption and photolysis experiments we use rotational spectroscopy to measure the gas-phase products of icy grain reactions. Previous results include testing detection limits of the system by temperature programmed desorption of methanol and water ices, photochemistry of gas-phase methanol, and detection of photodesorbed water from a pure water ice surface. Current work that will be discussed focuses on the detection of gas-phase CO and other photoproducts from an ice surface.