r0pt Figure Much of the Far-infrared radiation (FIR) emitted by the earth surface is trapped primarily by the insulating greenhouse effect. At the poles, the greenhouse effect is minimized by the nominal cold and dry atmospheric state. This is how a significant amount of absorbed solar energy is vented back to space, acting like a thermostat. Under these conditions, the effects of surface emissivity become disproportionately large and have a significant impact on the radiative balance. Earth system models have consistently under-estimated the rapid warming occurring in the Arctic, perhaps due to poor assumptions about the nature of far-infrared spectral emissions. The Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE) is a NASA Earth Ventures mission, currently in formulation, that would test the hypothesis that time-varying errors in FIR surface emissivity and atmospheric greenhouse effects bias the modeled energy balance that under-estimates Arctic warming. This presentation covers the processes involved in the energy balance, and how spectrally resolved measurements provide the means to extract critical information. We also discuss the instrument difficulties associated with remote measurements across the far-infrared, emphasizing the differing challenges associated with earth science vs. astrophysics. Finally, we provide an overview of the planned PREFIRE mission and how it would address these challenges.

r0pt Figure Water is the strongest greenhouse gas in the Earth atmosphere, which plays a critical role in the energy balance of the earth atmosphere. It has long been observed particularly in the far-infrared that there is significant longwave continuum absorption due to water vapor (dimers or multimers), not attributable to the Lorentz line contribution within 25 cm⁻¹ from the line center for individual water vapor lines. The MT_CKD model offers the water vapor continuum predictions, which are to be validated by a laboratory study in the far infrared. In order to directly measure this water vapor continuum absorption, we have obtained a series of spectra of water vapor broadened by Self, N₂, and O₂ in the 50 – 500 cm⁻¹ (200 – 20 μm) at temperatures between 251 and 296 K. For this, we used a coolable White cell system (whose optics are optimized for the far-infrared spectrometry) with passive temperature control, configured to the Fourier transform spectrometer, Bruker IFS-125HR at the Jet Propulsion Laboratory (JPL). We have been analyzing the spectra to make direct measurement of the far-infrared water continuum in two steps; (1) we obtained their transmission spectra by ratioing the sample spectrum to their corresponding background spectrum, (2) we obtained the continuum part of the transmission by dividing the measured spectrum by a synthetic spectrum of the resonant lines calculated using the HITRAN database. As shown in Figure 1, it has revealed the underlying water-water, water-O₂, and water-N₂ continua in the temperature range, depending on the spectrum type. The preliminary results from this on-going analysis are presented along with their comparison with the MT_CKD (ver.3.5) model predictions. Temperature dependence of the water vapor continuum will be discussed as part of future work.Government sponsorship acknowledged

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Government sponsorship acknowledged.

Life detection through chemical analysis requires nearly unambiguous detection of specific chemical biosignatures. The US Decadal Survey paper, Vision and Voyages for Planetary Science in the Decade 2013-2022, recommends ä detailed characterization of organics to search for signatures of biological origin, such as molecules with a preferred chirality or unusual patterns of molecular weights" as a key future investigation of life detection (page 240). While mass spectrometry has often been proposed for measuring the abundance patterns of molecular weights, it lacks the chirality detection capability required for chiral analyses of chiral molecules such as amino acids, and cannot uniquely identify specific structure-based isomers such as fatty acids. In this presentation we will report the status of the development of a millimeter-wave chirality spectrometer (ChiralSpec). ChiralSpec advances key technologies to enable chirality detection and discrimination of structural isomers with a simple instrument. It is applicable to mission focus areas such as Enceladus, Europa, Titan, and Mars. It could be used on planetary in-situ probes to measure amino acids and other organic molecules in the gas phase or brought into the gas phase. ChiralSpec employs an innovative microwave three-wave mixing technology for chirality detection and the cavity resonance technology for sensitivity enhancement. It can be operated under two modes: (1) survey mode, with the instrument acting as a traditional microwave spectrometer to characterize chemical composition and quantify abundance of planetary samples; and (2) chirality detection mode, with the instrument determining which enantiomer is in excess and how much it is in excess for each existing chiral molecule.

1-Adamantanol is a heavy non-rigid molecule consisting of 1-adamantyl and hydroxyl groups. Internal rotation about the 1-adamantyl 3-fold axis of symmetry was evidenced some time agoCraven, Spectrochim. Acta, 29A (1973) 679eading to an estimated value of the A-E splitting of 10 cm⁻¹. The microwave spectrum of 1-adamantanol was recorded laterCorbelli, Degli Esposti, Favero, and Lister, J. Chem. Soc. Trans. 2, 83 (1987) 2225n the 8 to 40 GHz region. Even though individual rotational lines could not be assigned, a value of 410 cm⁻¹ was obtained for V₃ the height of the barrier hindering the internal rotation. A cold molecular beam and a room temperature submillimeter wave spectra of 1-adamantanol were recorded in the 2-12 and 140-220 GHz ranges, respectively. 1404 parallel a-type transitions have been assigned in both spectra. A line frequency analysis of this new data set and of the perpendicular b-type clusters previously observed^b was carried out using an IAM approach.Hougen, J. Mol. Spectrosc.,  114 (1985) 395; and Coudert and Hougen, ibid, 130 (1988) 86n the paper, the new data and the results of the analysis will be presented. As 1-adamantanol is a nearly symmetric top molecule with an asymmetry parameter^b κ close to −0.99, asymmetry splittings could not be resolved in the new spectra and B−C was set to zero. Owing to the fact that the moment of inertia of 1-adamantyl about the axis of internal rotation is 400 times larger than that of the OH group about the same axis, ρ the parameter describing the rotational dependence of the torsional splitting is 0.9975. The implication for the energy level diagram of a value so close to 1 for this parameter will be discussed. Work is still in progress and it is hoped that it will be possible to identify torsional subbands in the crowded submillimeter wave spectrum recorded at room temperature.

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Craven, Spectrochim. Acta, 29A (1973) 679l Corbelli, Degli Esposti, Favero, and Lister, J. Chem. Soc. Trans. 2, 83 (1987) 2225i Hougen, J. Mol. Spectrosc.,  114 (1985) 395; and Coudert and Hougen, ibid, 130 (1988) 86I

Detection and characterization of short-lived species, or radicals, have been one of the main targets of high-resolution molecular spectroscopy. These kinetically unstable substances can be produced only in a very small amount under ordinary laboratory measurement conditions, it is essential to increase the sensitivity of the spectrometer and/or to improve the production efficiency of the molecules to be studied. Conventional microwave spectroscopy has taken an approach to raise the operating frequency to far-infrared region, expecting that effective absorption coefficient will increase. Sensitivity of the spectrometer in far-infrared region, or THz frequency region, has greatly improved thanks to succesful development of frequency multiplication techinques. Along with searching for an efficient production method of the short-lived species, many kinds of short-lived species can be possible to observe. Based on this situation, I would like to show several examples of far-infrared spectrosocpy of reactive species such as CH₂, NH₂, and CHF₂.

About 200 molecules have thus far been detected in the interstellar medium. Twenty-two are sulfur-bearing chemical compounds (and analogues of oxygenated species), making sulfur the tenth most abundant element in the galaxy. We report here the sub-THz spectroscopic observations of two reactive species: thioacetaldehyde (CH₃CHS) and NS⁺.Cernicharo J.; et al., 2018, ApJL L22, 852he latter new cation has been firmly detected for the first time towards many interstellar sources (cold molecular clouds, pre-stellar cores and shocks) using the IRAM-30m radiotelescope. Although a recent study of the chemistry of sulfur in cold dense clouds has been carried out Fuente A.; et al. A&A 593, (2016) A94he formation pathways of the sulfur species are still misunderstood.
The rotational spectrum of CH₃CHS was previously recorded up to 40 GHz.H. Kroto; et al., 1976, J. Mol. Spectrosc. 62, 346ew measurements performed up to 660 GHz represent a significant extension in terms of frequency range and analysis. The final spectroscopic analysis, including the internal rotation treatment, and searches for it towards SgrB2 and other sources will be presented.

Acknowledgements: These results were supported by the Programme National PCMI of CNRS/INSU, the French National Research Agency (ANR-13-BS05-0008 ”IMOLABS”), the CaPPA project (ANR-11-LABX-0005-01), the spanish MINECO (grants AYA2012-32032, AYA2016- 75066-C2-1-P, CSD2009-00038 and RyC-2014-16277) and the European Research Council (grant ERC- 2013-SyG 610256, NANOCOSMOS). Kharkov group acknowledge support of the Volkswagen foundation and assistance of the Science and Technology Center in Ukraine (STCU partner project P686).

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Cernicharo J.; et al., 2018, ApJL L22, 852T Fuente A.; et al. A&A 593, (2016) A94t H. Kroto; et al., 1976, J. Mol. Spectrosc. 62, 346N

HIFI survey for water vapor and ammonia in a sample of the carbon-rich Asymptotic Giant Branch (AGB) stars has shown that their presence in circumstellar envelopes is almost universal. Models for thermochemical equilibrium in the photospheres of the carbon-rich stars predict abundances of water and ammonia many orders below the observed values. Modeling of emission lines suggests, that both molecules should be formed very close to the photospheres of the central stars. The mechanism of formation of these molecules is uncertain, and the proposed hypotheses include shock chemistry, photochemistry driven by the UV radiation leaking into the inner part of clumpy envelope and formation on dust grains. We present the results of a detailed modeling of the lowest rotational transitions observed with the Herschel/HIFI instrument in the sample of C-rich AGB stars. The aim of this analysis is to constrain their abundances and, where possible, their formation radius. Excitation of both molecules is governed by the radiative pumping, mainly in their ν₂ vibrational modes. Models of molecules include a large number of levels in the ground and the first excited vibrational states. Ortho and para species of both molecules are treated separately. The transitions intensities are adopted from the BYTe (Yurchenko et al. 2011) and HITRAN (Rothman et al. 2009) databases for ammonia and water, respectively.

The infrared spectrum of ammonia has proven to be highly problematic for effective Hamiltonian analysis. As a result, previous studies failed to model the 3ν₂ and ν₂+ν₄ bands of the spectrum close to experimental accuracy. To remedy this a global fit of the 3ν₂ and ν₂+ν₄ bands has been undertaken using SPFIT. The analysis includes about 1000 newly assigned vibrational transitions in 3ν₂ to 2ν₂ as well as inversion transitions in 3ν₂ to 3ν₂. The spectra were a long path infrared absorption spectrum recorded with the Synchrotron light source at SOLEIL, with a path length of 180 m and a resolution of 0.0011 cm⁻¹ at room temperature and 1 Torr of pressure, and a mid-infrared discharge spectrum recorded similarly at SOLEIL, with a path length of 0.7 m and resolution .004 cm⁻¹ at 10 Torr and 900 K. Our fit has achieved experimental accuracy through the use of a number of terms that had not previously been in the Hamiltonian proving that ammonia is tractable to effective Hamiltonians despite previous beliefs.