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Register a new userExoMol line lists - XXIX. The rotation-vibration spectrum of methyl chloride up to 1200 K
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Comprehensive rotation-vibration line lists are presented for the two main isotopologues of methyl chloride, $^{12}$CH$_3{}^{35}$Cl and $^{12}$CH$_3{}^{37}$Cl. The line lists, OYT-35 and OYT-37, are suitable for temperatures up to $T=1200,$K and consider transitions with rotational excitation up to $J=85$ in the wavenumber range $0$--$6400,$cm$^{-1}$ (wavelengths $lambda> 1.56,mu$m). Over 166 billion transitions between 10.2 million energy levels have been calculated variationally for each line list using a new empirically refined potential energy surface, determined by refining to 739 experimentally derived energy levels up to $J=5$, and an established {it ab initio} dipole moment surface. The OYT line lists show excellent agreement with newly measured high-temperature infrared absorption cross-sections, reproducing both strong and weak intensity features across the spectrum. The line lists are available from the ExoMol database and the CDS database.
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A variationally computed $^{28}$SiH$_4$ rotation-vibration line list applicable for temperatures up to $T=1200,$K is presented. The line list, called OY2T, considers transitions with rotational excitation up to $J=42$ in the wavenumber range $0$--$5000,$cm$^{-1}$ (wavelengths $lambda> 2,mu$m). Just under 62.7 billion transitions have been calculated between 6.1 million energy levels. Rovibrational calculations have utilized a new `spectroscopic potential energy surface determined by empirical refinement to 1452 experimentally derived energy levels up to $J=6$, and a previously reported textit{ab initio} dipole moment surface. The temperature-dependent partition function of silane, the OY2T line list format, and the temperature dependence of the OY2T line list are discussed. Comparisons with the PNNL spectral library and other experimental sources indicate that the OY2T line list is robust and able to accurately reproduce weaker intensity features. The full line list is available from the ExoMol database and the CDS database.
A revised rotation-vibration line list for the combined hydrogen cyanide (HCN) / hydrogen isocyanide (HNC) system is presented. The line list uses {it ab initio} transition intensities calculated previously (Harris et al., ApJ, 2002, 578, 657) and extensive datasets of recently measured experimental energy levels (Mellau, J. Chem. Phys. and J. Mol. Spectrosc. 2010-2011). The resulting line list has significantly more accurate wavelengths than previous ones for these systems. An improved value for the separation between HCN and HNC is adopted leading to an approximately 25% lower predicted thermal population of HNC as a function of temperature in the key 2000 to 3000 K region. Temperature-dependent partition functions and equilibrium constants are presented. The line lists are validated by comparison with laboratory spectra and are presented in full as supplementary data to the article and at url{www.exomol.com}.
Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are expected to occur in the atmospheres of hot rocky super-Earth exoplanets but a lack of spectroscopic data is hampering their potential detection. Using robust first-principles methodologies, comprehensive molecular line lists for KOH and NaOH that are applicable for temperatures up to $T=3500$ K are presented. The KOH OYT4 line list covers the 0-6000 cm$^{-1}$ (wavelengths $lambda > 1.67$ $mu$m) range and comprises 38 billion transitions between 7.3 million energy levels with rotational excitation up to $J=255$. The NaOH OYT5 line list covers the 0 - 9000 cm$^{-1}$ (wavelengths $lambda > 1.11$ $mu$m) range and contains almost 50 billion lines involving 7.9 million molecular states with rotational excitation up to $J=206$. The OYT4 and OYT5 line lists are available from the ExoMol database at www.exomol.com and should greatly aid the study of hot rocky exoplanets.
A computed line list for hydrogen peroxide, H$_2{}^{16}$O$_2$, applicable to temperatures up to $T=1250$~K is presented. A semi-empirical high accuracy potential energy surface is constructed and used with an {it ab initio} dipole moment surface as input TROVE to compute 7.5 million rotational-vibrational states and around 20 billion transitions with associated Einstein-$A$ coefficients for rotational excitations up to $J=85$. The resulting APTY line list is complete for wavenumbers below 6~000 cm$^{-1}$ ($lambda < 1.67$~$mu$m) and temperatures up to 1250~K. Room-temperature spectra are compared with laboratory measurements and data currently available in the HITRAN database and literature. Our rms with line positions from the literature is 0.152 cm and our absolute intensities agree better than 10%. The full line list is available from the CDS databas
An accurate line list, called XABC, is computed for nitric oxide which covers its pure rotational, vibrational and rovibronic spectra. A mixture of empirical and theoretical electronic transition dipole moments are used for the final calculation of $^{14}mathrm{N}^{16}mathrm{O}$ rovibronic $mathrm{A},^2Sigma^+$ -- $mathrm{X},^2Pi$, $mathrm{B},^2Pi$ -- $mathrm{X}^2Pi$ and $mathrm{C},^2Pi$ -- $mathrm{X},^2Pi$ which correspond to the $gamma$, $beta$ and $delta$ band systems, respectively, as well as minor improvements to transitions within the $mathrm{X},^2Pi$ ground state. The work is a major update of the ExoMol NOname line list. It provides a high-accuracy NO ultraviolet line list covering the complicated regions where the $mathrm{B},^2Pi$-$mathrm{C},^2Pi$ states interact. XABC provides comprehensive data for the lowest four doublet states of NO in the region of $lambda > 160 ~ mathrm{nm}$ ($tilde{ u} < 63~000~mathrm{cm}^{-1}$) for the analysis of atmospheric NO on Earth, Venus or Mars, other astronomical observations and applications. The data is available via www.exomol.com.
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