In 1972, Kaifu et al. and ScovilleKaifu, N., Kato, T., & Iguchi, T. 1972, Nature, 238, 105: Scoville, N. Z. 1972, ApJ, 175, L127laimed the existence at the Galactic center (GC) of a circular Expanding Molecular Ring (EMR) of radius  ∼  200 pc from longitude-velocity diagram ((l,v) diagram), of radio absorptions of OH and H₂CO, respectively. After the development of a theory of gas motions in a barred potential by Binney et al. (1991) Binney, J., Gerhard, O. E., Stark, A. A., Bally, J., & Uchida, K. I. 1991, MNRAS, 252, 210 however, this circular shape fell out of favor and instead elliptic orbits of the gas with high eccentricity (the x₁ orbit of Lindblad resonance) are now widely believed. Meanwhile a recent (l,v) diagram obtained from infrared absorption spectra of H₃⁺ by Oka et al. (2019, 2020)Part I: Oka, T., Geballe, T. R., Goto, M., Usuda, T., McCall, B. J., & Indriolo, N. 2019, ApJ, 883:54(31pp) Part II: Oka et al. 2020 in preparationn the GC's central 300 pc called the Central Molecular Zone (CMZ) has revived the circular shape of the CMZ. Observed gas motions on much larger scales (on the order of 3 kpc Liszt & Burton 1978Liszt, H. S., & Burton W. B. 1978, ApJ, 226, 790 and face-on views of external galaxies (e.g. Figure 14 of Kormendy & Kennycut 2004Kormendy, J., Kennicut, Jr., R. C. 2004, ARAA, 42, 60 provide evidence for the x₁ orbit. However, we find the application of the same theory to the CMZ, more than 10 times smaller, where the barred potential is not identified, is unjustified. We believe the face-on view of the CMZ as tracing ellipses with high eccentricity is not real.

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Footnotes:

Kaifu, N., Kato, T., & Iguchi, T. 1972, Nature, 238, 105: Scoville, N. Z. 1972, ApJ, 175, L127c Binney, J., Gerhard, O. E., Stark, A. A., Bally, J., & Uchida, K. I. 1991, MNRAS, 252, 210, Part I: Oka, T., Geballe, T. R., Goto, M., Usuda, T., McCall, B. J., & Indriolo, N. 2019, ApJ, 883:54(31pp) Part II: Oka et al. 2020 in preparationi Liszt, H. S., & Burton W. B. 1978, ApJ, 226, 790) Kormendy, J., Kennicut, Jr., R. C. 2004, ARAA, 42, 60)

We report the observation and assignment of the rotational spectra of the isotopically chiral molecule, trans-2,3-dideutero-oxirane (c-CHD-CHDO) measured in the Gigahertz range of 62-110 GHz and in the Terahertz range, 25-80 cm⁻¹(instrumental resolution of 0.00052 cm⁻¹). Normal oxirane (c-C₂H₄O) has been detected by astrophysical spectroscopy in space.J. E. Dickens, et al., ApJ, 1997, 489, 753; M. Ikeda, et al., ApJ, 2001, 560, 792; J. M. Lykke, et al., A&A,2017, 597, A53.A small number of lines of trans−2,3−dideutero−oxirane had been previously analyzed in the microwave regionC. Hirose, Bull. Chem. Soc. Jap., 1974, 47, 1311. up to 70 GHz. We have recently S. Albert, Z. Chen, K. Keppler, Ph. Lerch, M. Quack, V. Schurig, O. Trapp, Phys.Chem.Chem.Phys., 2019, 21, 3669 measured and successfully analyzed the rotational spectrum of monodeutero−oxirane between 65 and 119 GHz using our GHz spectrometer M. Suter, M. Quack, Appl. Opt., 2015, 54 (14), 4417; S. Albert, Z. Chen, C. Fabri, Ph. Lerch, R. Prentner, M. Quack, Mol. Phys., 2016, 114, 2751., and in the 0.75 to 2.5 THz range measured with our FTIR setup S. Albert, Ph. Lerch, M. Quack, ChemPhysChem, 2013, 14, 3204; S. Albert, K. K. Albert, Ph. Lerch, M. Quack, Faraday Discuss., 2011, 150, 71. at the Swiss Light Source.In the current work, we were able to assign and analyze more than 2500 rotational transitions of the vibronic ground state of trans−2,3−dideutero−oxirane up to J=65. The molecule is also of interest in the context of molecular parity violation, similar to the related molecule fluoro−oxirane H. Hollenstein, D. Luckhaus, J. Pochert, M. Quack, G. Seyfang, Angew. Chemie, 1997, 109 (1,2), 136; R. Berger, M. Quack, J. Stohner, Angew. Chem. Intl. Ed., 2001, 40, 1667.. Our results are important in relation to isotopic chirality and parity violation C. Hirose, Bull. Chem. Soc. Jap., 1974, 47, 1311.M. Suter, M. Quack, Appl. Opt., 2015, 54 (14), 4417; S. Albert, Z. Chen, C. Fabri, Ph. Lerch, R. Prentner, M. Quack, Mol. Phys., 2016, 114, 2751.H. Hollenstein, D. Luckhaus, J. Pochert, M. Quack, G. Seyfang, Angew. Chemie, 1997, 109 (1,2), 136; R. Berger, M. Quack, J. Stohner, Angew. Chem. Intl. Ed., 2001, 40, 1667.

Glycolaldehyde (CHOCH₂OH) and ethylene glycol (HOCH₂CH₂OH) are among many complex organic molecules (COM) detected in the interstellar medium (ISM). Astrophysical models proposed very often that the formation of these compounds would be directly linked to the hydrogenation of glyoxal (CHOCHO), a potential precursor which is not yet detected in the ISM. We have performed, in the present work, surface and bulk hydrogenations of solid CHOCHO under ISM conditions in order to confirm or invalidate the astrophysical modeling of glyoxal transformation. Our results show that the hydrogenation of glyoxal does not lead to the formation of detectable amounts of heavier organic molecules such as glycolaldehyde and ethylene glycol but rather to lighter CO-bearing species such as CO, H₂CO and CO−H₂CO, a reaction intermediate resulting from an H-addition-elimination process on CHOCHO and where CO is linked to H₂CO. The solid phase formation of such a reaction intermediate has been confirmed through the neon matrix isolation of CO−H₂CO species.

The CDMSShortcut: cdms.de; web address: https://cdms.astro.uni-koeln.de/. The CDMS is supported by the Verbundforschung Physik of the BMBF (German Ministry of Science and Education), project ID 05A17PK1.as founded more than 20 years ago to provide in its catalog section line lists of mostly molecular species which were or may be detected in space by radio astronomical means.H. S. P. Müller et al., Astron. Astrophys. 370 (2001) L49.he line lists are generated by fitting critically evaluated experimental data, mostly from laboratory spectroscopy, to established Hamiltonian models. The assessment of the experimental data and of the Hamiltonian model is very importante.g., C. P. Endres et al., J. Mol. Spectrosc. 327 (2016) 95.nd will be discussed in some detail. There are 998 entries in the CDMS catalog as of Feb. 01 2020. A large fraction of the contribution will deal with recent entries and with potential laboratory needs which are often linked to Atacama Large Millimeter/submillimeter Array projects such as (R)EMoCA(Re-) Exploring Molecular Complexity with ALMA, A. Belloche et al., Astron. Astrophys. 587 (2016) A91 & 628 (2019) A10. PILSThe ALMA Protostellar Interferometric Line Survey, J. K. Jørgensen et al., Astron. Astrophys. 595 (2016) A117. and ATOMIUM.ALMA Tracing the Origins of Molecules forming dust In oxygen-rich M-type stars, L. Decin et al. (2020) submitted.hese include numerous diatomics, frequently containing metals, with highly excited states and isotopic species for several molecules already detected in space for the last project and excited states or isotopic species of known interstellar organic molecules, but also several new ones for the other projects. Other sections of the classical CDMS include a page on Molecules in Space and a help page for users of Pickett's SPFIT/SPCAT programs. There is also a VAMDC compatible incarnation of the CDMS which is linked to a plethora of other spectroscopic, collisional, and kinetic databases via the Vitual Atomic and Molecular Data Centre portal.http://www.vamdc.org/html:<hr /><h3>Footnotes: Shortcut: cdms.de; web address: https://cdms.astro.uni-koeln.de/. The CDMS is supported by the Verbundforschung Physik of the BMBF (German Ministry of Science and Education), project ID 05A17PK1.w H. S. P. Müller et al., Astron. Astrophys. 370 (2001) L49.T e.g., C. P. Endres et al., J. Mol. Spectrosc. 327 (2016) 95.a (Re-) Exploring Molecular Complexity with ALMA, A. Belloche et al., Astron. Astrophys. 587 (2016) A91 & 628 (2019) A10., The ALMA Protostellar Interferometric Line Survey, J. K. Jørgensen et al., Astron. Astrophys. 595 (2016) A117., ALMA Tracing the Origins of Molecules forming dust In oxygen-rich M-type stars, L. Decin et al. (2020) submitted.T http://www.vamdc.org/

The growth of molecular complexity in diffuse molecular clouds has remained a long standing problem in astrophysics. On the one hand, we have simple hydrides discovered with the Herschel space telescope and small hydrocarbon species such as C2H, while on the other we have monolithic fullerenes including C60 and . The chemical and physical relationship between the two ends of this dichotomy remains elusive, and the species that connect the small with the large - simple, medium-sized organic molecules possessing > 3 carbon atoms - have not yet been found.

Recently, we have begun a detailed observing campaign with the 100 m Green Bank Telescope (Abstract 4275) that aims to systematically explore the growth of chemical complexity in diffuse clouds. Some of our key findings include strong absorption by C3H+, and perhaps more excitingly, C4H, which to our knowledge is the largest carbon chain radical detected so far in the diffuse gas. In order to fully understand the behavior of these species in what was thought to be highly hostile environments for complex chemistry, we require accurate theoretical predictions of structures and thermochemical properties pertaining to molecules that are thought to play important roles in these regions. In this talk, I will discuss our latest efforts to perform high accuracy quantum chemical calculations of several small hydrocarbon species, both as to constrain the relative energetics of their isomers, as well as high precision predictions of their spectroscopic constants to guide their searches.

The growth of molecular complexity in diffuse molecular clouds poses an important and interesting puzzle in astrophysics. The molecular inventory known to us currently comprises simple hydrides and small hydrocarbon species (containing up to 3 carbon atoms) on the one hand, and a very large molecule - the fullerene cation - on the other. The chemical and physical relationship between the two ends of this dichotomy remains poorly understood, and the species that are intermediate in size have not yet been found, due to the lack of deep astronomical, theoretical, and laboratory searches. Recently, we have begun a dedicated observing campaign with the 100-m Green Bank Telescope (Abstract 4275) that aims to systematically explore the growth of chemical complexity in diffuse clouds. Some of our key findings include strong absorption by C₃H⁺, and perhaps more excitingly, C₄H, which to our knowledge is the largest carbon chain radical detected so far in the diffuse gas. Understanding the presence of these species in the harsh environment of the diffuse gas requires accurate theoretical predictions of the structures and energetics of key reactive intermediates involved in their production. In this talk, I will discuss our efforts to perform high accuracy quantum chemical calculations of several small hydrocarbon species, both as to constrain the relative energetics as well as high precision predictions of spectroscopic parameters to guide laboratory and astronomical searches.

Ever-increasingly complex molecules are being searched for in the interstellar medium, and following the detections of propylene oxide McGuire, B. A., Carroll, P. B., Loomis, R. A., et al. 2016, Science, 352, 1449nd benzonitrile McGuire, B. A., Burkhardt, A. M., Kalenskii, S., et al. 2018, Science, 359, 202 chiral and aromatic molecules are becoming appealing targets for laboratory studies and interstellar searches. The chiral molecule styrene oxide (C₆H₅C₂H₃O), also known as phenyloxirane, is an epoxide (R−C₂H₃O) with a phenyl ring as the (-R) substituent. With a single conformer and a permanent dipole moment of about 1.8 Debye, styrene oxide emerges as an interesting chiral molecule for astrochemical investigations. We investigated the microwave and millimeter wave spectrum of styrene oxide and analysed the ground-state rotational spectrum as well as rotational transitions from low-energy vibrationally excited states. Chirped-pulse Fourier-transform microwave and millimeter-wave spectroscopy and frequency modulation absorption spectroscopy were used to record spectra in the regions of 2-12 GHz, 75-110 GHz, 170-220 GHz, and 260-330 GHz. From the spectral analysis, a set of precise rotational and centrifugal distortion parameters up to the sextic order was obtained. Our accurate predictions of styrene oxide into the (sub-)millimeter range are mandatory for radio astronomy searches with state-of-the-art observational facilities, such as ALMA. In addition, we assigned the spectra of all singly-substituted ¹³C and ¹⁸O isotopologues, which allowed us to determine the gas phase structure of the molecule experimentally. McGuire, B. A., Carroll, P. B., Loomis, R. A., et al. 2016, Science, 352, 1449a McGuire, B. A., Burkhardt, A. M., Kalenskii, S., et al. 2018, Science, 359, 202,

A new experimental approach to studying interstellar and cometary ice analogs has been designed that uses millimeter/submillimeter (mm/submm) spectroscopy coupled with mass spectrometry to identify desorbed gas-phase species, and infrared (IR) spectroscopy to monitor the photochemistry within icy mantles photolyzed by ultra-violet (UV) light. Rotational spectroscopy provides several benefits for laboratory ice studies including the capability of distinguishing structural (e.g. methyl formate (HCOOCH₃) and glycolaldehyde (HCOCH₂OH)) and conformational (e.g. cis- and trans-methyl formate) isomers, determining the rotational temperature of desorbed species, and laboratory spectra that are directly comparable to mm/submm spectra from ground- and space-based telescopes. Here we will show how surface binding energy can be determined via mm/submm spectroscopic detection of thermally desorbed ices, and how to combine IR spectroscopy, mass spectrometry, and mm/submm spectroscopy to determine UV photoproducts of methanol ices.

To understand the chemical processes taking place in the interstellar medium, it is necessary to recreate these interactions in the laboratory at similar conditions to their environment in space, which can be as cold as 10 K. A well-known way to study reaction kinetics and dynamics at cold temperatures is the CRESU (a French acronym for reaction kinetics in supersonic flow) technique. However, very few CRESU experiments exist that are able to determine reaction products. Recently, the combination of chirped-pulse Fourier transform microwave (CPFTMW) spectroscopy with the CRESU technique, termed CPUF (chirped pulse in uniform flows), was developed through collaboration with the Suits and Field groups.J. Phys. Chem. Lett. 2015, 6, 9, 1599-1604PUF has proven capable of detecting multiple reaction products, simultaneously, within a cold flow. The CRESUCHIRP project at the Institut de Physique de Rennes aims to discover more about cold reactions through a new CPUF experiment. A novel CPFTMW spectrometer operating in the Ka-band (26.5 GHz – 40 GHz) has been built and tested on a number of benchmark systems, such as carbonyl sulfide, vinyl cyanide and benzonitrile. Rotational temperature and pressure-broadening data were able to be determined at room temperature in a flow cell, and within CRESU flows. Furthermore, some photodissociation and bimolecular reactions were able to be observed. However, the high collisional rates within CRESU flows greatly attenuate the detectable signal in CPFTMW spectroscopy, so, in order to observe heavy products with large pressure-broadening rates, we are developing two complementary additions to our experiment. The first to be implemented is skimmer which samples the CRESU flow into a secondary chamber differentially-pumped to low pressure. Preliminary results from this venture will be presented, as well as future plans for the CRESUCHIRP project.

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J. Phys. Chem. Lett. 2015, 6, 9, 1599-1604C

O(¹D) is well known to undergo exothermic insertion reactions into X-H bonds ,where X is C, N, or H. O(¹D) insertion reactions can therefore be used as a tool for the formation of unstable species for collection of their rotational spectrumB. M. Hays, N. Wehres, B. Alligood DePrince, A. A.M. Roy, J. C. Laas, S. L. Widicus Weaver, Chem. Phys. Lett., 630, 18 (2015) Aminomethanol, predicted to form via insertion into methylamineB. M. Hays, S. L. Widicus Weaver, J. Phys. Chem. A, 117, 32, 7142-7148 (2013)^,M. E. Wolf, P. R. Hoobler, J. M. Turney, H. F. Schaefer III, Phys. Chem. Chem. Phys., 2019,21, 24194−24205s an important interstellar prebiotic precursor to the amino acid glycine. However, due to its instability under terrestrial conditions it still evades spectral detection. We have completed a set of experiments examining the products of O(^1 M. E. Wolf, P. R. Hoobler, J. M. Turney, H. F. Schaefer III, Phys. Chem. Chem. Phys., 2019,21, 24194-24205i