Elucidation of rotational-interaction coupling and collision-induced effects in rovibrational transitions of β-N2O isotopologue at 7.8 µm mid-infrared region by cavity ring-down spectroscopy

Abstract

High-sensitive cavity ring-down spectroscopy (CRDS) coupled with a cw-quantum cascade laser operating at 7.8 μm mid-infrared (MIR) region has been employed to investigate the rovibrational interaction coupling for various MIR rotational transitions of the P-and R-branches in the ν1 fundamental vibrational band (1000 ← 0000) of the β-site-specific isotopologue of nitrous oxide (β-N2O) i.e., 15N14N16O. The coupled rotational interaction was experimentally quantified from the high-resolution CRDS data and a data-driven approach was taken for the approximation of the Herman-Wallis series. Moreover, J-dependent pressure-broadened absorptions and their collision lifetimes in response to foreign-perturbing gas molecules were investigated to understand the collision-induced rotational quantum effect in β-N2O molecule. This study reveals an experimental elucidation of the fundamental infrared physics underlying rovibrational interaction and its coupling to the vibrational and rotational degrees of freedom for a non-centrosymmetric linear polyatomic molecule possessing a permanent dipole moment. Moreover, the experimentally probed interference-free spectral lines of β-N2O molecule attributing different spectroscopic signatures in the MIR region may drive new applications in environmental monitoring, biological and biomedical diagnostics in the future.