ExoMol line lists -- LIX. High-temperature line list for N$_2$O

TL;DR

This paper presents new high-temperature line lists for five isotopologues of N$_2$O, computed with advanced variational methods and empirical data, covering extensive rotational and vibrational states for improved spectroscopic modeling.

Contribution

Introduction of a new empirical potential energy surface and an efficient symmetry group for accurate line list calculations of N$_2$O isotopologues.

Findings

Line lists cover up to J=160 and 20000 cm$^{-1}$ range.

Excellent agreement with experimental spectra achieved.

Comparison with existing databases shows improvements.

Abstract

New hot line lists for five isotopologues of N$_2$O are presented, for the parent $^{14}$N$_2^{16}$O and 4 singly substituted species $^{14}$N$_2^{17}$O, $^{14}$N$_2^{18}$O, $^{14}$N$^{15}$N$^{16}$O and $^{15}$N$^{14}$N$^{16}$O. The line lists have been computed with the variational program TROVE using a new empirical potential energy surface (PES) and an accurate ab initio dipole moment surface of N$_2$O Ames-1. The PES was obtained by fitting to experimentally derived energies of N$_2$O compiled using the well established MARVEL procedure. Here we also introduce an `artificial symmetry group' $C_{\rm ns}$(AEM) for an efficient construction of rotation-vibrational basis set of a linear non-symmetric triatomic molecule of the XYZ type. The line lists cover the rotational excitations up to $J=160$ and the wavenumber range up to 20000 cm$^{-1}$. MARVEL energies are also used to improve predicted line positions resulting in excellent agreement with the available experimental spectra, as demonstrated. An extensive comparison with existing line lists for N$_2$O HITRAN, HITEMP, NOSL-296, NOSD-1000 and Ames-296K is provided. The line lists are freely accessible from www.exomol.com.