High-resolution rovibrational cavity ring-down spectroscopy of (1200←0200) vibrational band of β-site-specific N2O isotopologue near 7.8 µm region

An external-cavity quantum cascade laser (EC-QCL) coupled cavity ring-down spectroscopy was employed at 7.8 µm to investigate high-resolution rovibrational spectral features associated with the P- and R-branches of the 12⁰0←02⁰0 vibrational hot band transition of the β-site-specific isotopologue of nitrous oxide, i.e., ¹⁵N¹⁴N¹⁶O molecule. The air-broadening phenomena of several probed rotational transitions of β-N₂O were examined by calculating the pressure-broadening coefficients. We calculated significant spectroscopic parameters such as the band centre, rotational constant, and centrifugal distortion constant for this selected vibrational band. Subsequently, we elucidated the dependence of rovibrational Einstein A coefficients on the rotational quantum number (J) and estimated the vibrational contribution of the Einstein A coefficients. We also determined the Herman Wallis coefficients corresponding to this 12⁰0←02⁰0 vibrational band. Finally, we investigated the line-oscillator strengths of the experimentally probed rovibrational transitions to gain deeper insights into the fundamental aspects of high-resolution spectroscopy of site-specific β-N₂O molecules. These new high-resolution spectroscopic features of the β-N₂O isotopologue will significantly enhance our understanding of the fundamental rovibrational spectroscopy of linear polyatomic molecules.

Graphical Abstract

This work shows the high-resolution fundamental rovibrational spectroscopy of the 12⁰0←02⁰0 vibrational hot band of site-specific ¹⁵N¹⁴N¹⁶O isotopologue of nitrous oxide using quantum cascade laser (QCL) coupled cavity ring-down spectroscopy at 7.8 µm region.