The Atacama Large Millimeter/sub-millimeter Array (ALMA) provides a view of our molecular universe with unprecedented sensitivity and resolution over more than 850 GHz in bandwidth from 84 - 950 GHz. In this talk, I will cover three recent results that showcase not only ALMA's power to probe interstellar chemical evolution, but also the critical role of laboratory molecular spectroscopy efforts in interpreting ALMA observations. At lower frequencies, I will discuss our recent detections of the extraordinarily vibrationally excited inorganic salts NaCl and KCl in the disk of Orion Src I, which may prove to be a unique, and much needed, probe of embedded disks around high-mass protostars. Moving up both in frequency and complexity, I will highlight our detection of methoxymethanol (CH₃OCH₂OH) in the high-mass star-forming region NGC 6334I in very high abundance that was directly enabled by complementary laboratory spectroscopy work. Finally, I will discuss the first broadband line survey conducted with ALMA at Bands 9 and 10, again toward NGC 6334I. I will comment on not only the power and quality of high-frequency observations with ALMA but also the need for renewed laboratory efforts at these frequencies, as highlighted by glycolaldehyde (HC(O)CH₂OH) and ethylene glycol ((CH₂OH)₂).

Methyl isocyanate (CH₃NCO) is one of the most abundant species detected on the surface of the 67P/Churyumov-Gerasimenko comet.Goesmann, F., Rosenbauer, H., Bredehoft, J.H., et al. 2015, Science, 349, aab0689.t has also been discovered in space towards the Orion clouds where a large number of rotational lines arising from energy levels with K ≤ 3 were reported.Cernicharo, J., Kisiel, Z., Tercero, B., et al. 2016, A&A, 587, L4.n the present work, Stark-modulation spectroscopy was used to record the room temperature rotational spectrum of CH₃NCO in the spectral region from 32 to 90 GHz and to assign rotational transitions up to K = 10. These new assignments were subsequently followed up to 364 GHz. Also, first laboratory measurements between 50 and 300 GHz have been performed for CH₃N¹³CO and ¹³CH₃NCO isotopologues. Updated extensive line lists along with new sets of spectroscopic parameters provided in this work meet the needs for further detections of CH₃NCO in space.

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Footnotes:

Goesmann, F., Rosenbauer, H., Bredehoft, J.H., et al. 2015, Science, 349, aab0689.I Cernicharo, J., Kisiel, Z., Tercero, B., et al. 2016, A&A, 587, L4.I

Methyl isocyanate is a non-rigid quasi-symmetric top molecule displaying a torsion of its methyl group and a large amplitude bending mode.Kr eglewski, J. Molec. Spectrosc. 105 (1984) 8; and Koput, ibid. 106 (1984) 12he torsion is nearly free as the hindering barrier is only 20 cm⁻¹. The barrier to linearity, also very low, is on the order of 920 cm⁻¹. Although the a-type transitions of methyl isocyanate have already been recorded up to the submillimeter wave domain,Koput, J. Molec. Spectrosc. 115 (1986) 131; and Cernicharo et al., A&A  587 (2016) L4pectroscopic information is still lacking, especially concerning the cation. Threshold photoelectron spectroscopy has been used to obtain spectroscopic information on the cationic species () of methyl isocyanate. The spectrum recorded from 84000 to 94000 cm⁻¹ (10.4 to 11.6 eV) using VUV synchrotron radiation displays several sharp features superimposed on a broad feature spanning nearly 8000 cm⁻¹. As shown by the ab initio calculations carried out in this work, the ground electronic state of the cation is doubly degenerate and is split into a lower X̃⁺ and an upper Ã⁺ substate by vibronic couplings. The ground electronic state of the neutral and the X̃⁺ substate of the cation are characterized by similar values of the methyl group internal rotation barrier. As for the Ã⁺ substate of the cation, a much larger value shifted by π/3 was calculated. Accounting for the two large amplitude motions and for the overall rotation, a calculation of the rovibronic energies of the neutral and the cationic species is in progress and should allow us to model the TPES spectrum. This calculation relies on Gaussian quadrature to treat the singularity at the linear configuration.Coudert, Gans, Holzmeier, Loison, Garcia, Alcaraz, Lopes, and Röder, J. Chem.\ Phys. 149 (2018) 224304he strong dependence on the methyl group internal rotation barrier on the bending angle is also taken into account. In the talk, the results of the rovibronic energies calculation will be reported and the experimental TPES spectrum will be compared to the theoretical one.

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Footnotes:

Kr eglewski, J. Molec. Spectrosc. 105 (1984) 8; and Koput, ibid. 106 (1984) 12T Koput, J. Molec. Spectrosc. 115 (1986) 131; and Cernicharo et al., A&A  587 (2016) L4s Coudert, Gans, Holzmeier, Loison, Garcia, Alcaraz, Lopes, and Röder, J. Chem.\ Phys. 149 (2018) 224304T

Hydantoin (Imidazolidine-2,4-dione, C₃H₄N₂O₂ is a five-membered heterocyclic compound, and has been regarded as a direct precursor of glycine, the simplest amino acid. The molecule was detected in carbonaceous chondrites together with several kinds of amino acids.A. Shimomiya, and R. Ogasawara, Orig. Life Evol. Biosph. 32, 165 (2002)e have measured pure rotational spectrum of the molecule in its ground and vibrationally excited states, and have provided the molecular line frequency list in the millimeter-wave region for astronomical search.H. Ozeki, R. Miyahara, H. Ihara, S. Todaka, K. Kobayashi, and M. Ohishi, Astron. Astrophys. 600 A44 (2017).-methyl hydantoin is the simplest chiral molecule among hydantoins, because either of the hydrogen atoms bonded to the C5 position of the five-membered ring is asymmetrically substituted. The molecule becomes a direct precursor of alanine, the simplest chiral amino acid. We have tried to observe pure rotational spectrum of 5-methyl hydantoin in the millimeter-wave to sub-millimeter-wave region. Guided with quantum chemical calculation, several spectral lines can be assigned to b-type transitions. A. Shimomiya, and R. Ogasawara, Orig. Life Evol. Biosph. 32, 165 (2002)W H. Ozeki, R. Miyahara, H. Ihara, S. Todaka, K. Kobayashi, and M. Ohishi, Astron. Astrophys. 600 A44 (2017).5

The aldimines are important to understand amino acids formation process as they appear in reaction scheme of Strecker-type synthesis. It seems reasonable to propose syntheses in the solid phase but the formation process is not clearly established. The number of imines and amines detected in the interstellar medium is limited, mainly due to lack of spectroscopic data. We present here the studies of ethanimine (CH₃CHNH) and methylimino-acetonitrile (CH₃N=CHCN). Both of them have has two isomers E and Z with E one being the most stable. These molecules represent a particular case where a quite high (570 and 714 cm⁻¹ respectively) internal rotation barrier is combined with relatively a high ρ value (close to 0.3) making analysis of the spectra rather delicate. The fits were performed using a version of RAM36 codeIlyushin, V.V. et al;J. Mol. Spectrosc. 259, (2010) 26hich includes the treatment of the nuclear quadrupole hyperfine structure. Ethanimine was detected already in ISMLoomis, R. A.; et al. ApJ. Lett. 765,(2013) L9 but the spectrosocpic analyses were limited to low K_a valuesLovas, F. J.; et al. J. Chem. Phys. 72, (1980) 4964^, Melli A.; et al. ApJ855, (2018) 123.

We present the first spectroscopic results on a newly built broadband Fourier transform millimeterwave spectrometer for the laboratory which employs the same detection system as that present in radio-telescopes. The spectrometer is equipped with Q-band (31.5-50GHz) and W-band (72-116GHz) receivers, very sensitive to the rotational emission of the molecules present in a one meter Gas Cell. The technique provides large instantaneous bandwidth, spectral purity, and a linear dependence of the signals with the partial pressure so that it is perfectly suited for high resolution emission spectroscopy of molecules of astrophysical importance. The full description of the cell can be found in the literatureI. Tanarro et al. 2019, A&A, 609, A15^,J. Cernicharo et al., 2019, A&A In the present contribution we will show the capabilities of the spectrometer. The Gas Cell has been initially tested with molecules whose rotational spectrum was well known (CH_3CN, OCS, SO_2 J. Cernicharo et al., 2019, AA.

Several molecules containing a peptidic bond in their structure such as formamide (HCONH₂) and some derivative compounds have been already found in the interstellar mediumR.H. Rubin et al., 1971, ApJL, 169, L39, and see e.g. A.J. Remijan et al., 2014, ApJ, 783, 77 In case of N-ethylformamide (HCONHCH₂CH₃), only the microwave spectrum is known up to 20 GHz hence the rotational constants for the conformers found are not accurate enough to detect the molecule in the interstellar medium.
In the present work we have employed the Nanocosmos Gas Cell spectrometer to record the millimeterwave spectrum of N-ethylformamide. The recently built broadband Fourier transform millimeterwave spectrometerI. Tanarro et al., 2018, A&A, 609, A15 and J. Cernicharo et al., 2019, A&Amploys radio astronomical receivers for the Q-band (31.5-50GHz) and W-band (72-116GHz) to detect the thermal emission of the molecules in the Gas Cell chamber. The aim consists on establishing the concept of Nanocosmos Gas Cell as a new tool for high resolution broadband molecular spectroscopy in the millimeterwave region. In this study not only the ground state but also a higher energy conformer and some vibrational excited states have been identified and analyzed. The rotational constants will be used to search for this molecule in the space. R.H. Rubin et al., 1971, ApJL, 169, L39, and see e.g. A.J. Remijan et al., 2014, ApJ, 783, 77. I. Tanarro et al., 2018, A&A, 609, A15 and J. Cernicharo et al., 2019, A&Ae

Methoxyisocyanate, CH₃ONCO is a methoxy derivative of isocyanic acid HNCO detected in the interstellar medium back in 1972Snyder, L.E. and Buhl, D. 1972, ApJ, 177, 619 Recent detections of methyl isocyanate, a methyl derivative of HNCO, towards Sgr B2(N)Halfen, D.T., Ilyushin, V.V. and Ziurys, L.M. 2015, ApJ, 812, L5 and in the OrionCernicharo, J. et al. 2016, A&A, 587, L4 as well as the detection of methoxymethanolMcGuire, B.M. 2017, ApJ 851, L46 (2017)otivated us to study the rotational spectrum of CH₃ONCO as a candidate molecule for searches in the interstellar medium. The previously presented study of the rotational spectrum of methoxyisocyanatePienkina, A. et al. 2017, 72nd ISMS, WA03howed the complexity of the problem owing to the large amplitude motion, a skeletal torsion along ON bond. The analysis revealed the existence of the "ladder" Coriolis-type interactions between the ground and lowest skeletal torsional states. We present here the extension of the rotational spectrum analysis that includes new types of resonances as well as the assignment of new excited vibrational states of methoxyisocyanate. In particular, the inclusion of new resonances permitted to assign and fit within experimental accuracy high K_a transitions of the ground vibrational state. This work was supported by the CNES and the Action sur Projets de l’INSU, PCMI.

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Footnotes:

Snyder, L.E. and Buhl, D. 1972, ApJ, 177, 619. Halfen, D.T., Ilyushin, V.V. and Ziurys, L.M. 2015, ApJ, 812, L5, Cernicharo, J. et al. 2016, A&A, 587, L4, McGuire, B.M. 2017, ApJ 851, L46 (2017)m Pienkina, A. et al. 2017, 72nd ISMS, WA03s

Density functional theory cluster calculations indicate that the intermediate HOCHNC readily forms when C⁺ reacts with HCN embedded in the surface of an icy grain mantle. Subsequent H addition to HOCHNC yields the iscyano compound HOCH₂NC. There is enough energy from the H addition for HOCH₂NC to isomerize to HOCH₂CN (glycolonitrile), an important prebiotic molecule that was recently detected with ALMA observations toward the solar-type protostellar source IRAS 16293-2422 B by Zeng et al. [MNRAS 2019, 484, L43]. It was found that H can also add to HOCHNC to form HOCHNCH without a barrier. The analogous reactions of C⁺ with HNC in ice will also be discussed. Vibrational spectra of the various ice-bound reactants, intermediates, and products will be presented. The calculations were performed with B3LYP using aug-cc-pVDZ sets on C, N, and O and cc-pVDZ sets on H.