Ro-vibrational spectral features and pressure broadening dynamics of dideutero-methane (12CH2D2) in the ν9(B2) fundamental band

• Published in: Journal of molecular spectroscopy 2022-02, Vol.384, p.111572, Article 111572
• Main Authors: Panda, Biswajit, Pal, Ardhendu, Maithani, Sanchi, Maity, Abhijit, Pradhan, Manik
• Format: Article
• Language: English
• Subjects: Cavity ring-down spectroscopy; Dideuteromethane; High-resolution laser spectroscopy; Methane isotopes; Quantum cascade laser
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2022.111572

[Display omitted] •Spectral features and dynamics of 12CH2D2 isotopomer has been explored using high-resolution CRDS technique.•Theoretical simulations using Gaussian 16 and PGOPHER have been performed.•Spectroscopic parameters like absorption cross-section, pressure broadening co-efficient have been calculated using various perturbing gases.•Dependency of pressure broadening coefficient on the rotational quantum number (J) have been analysed.•Our highly sensitive spectroscopic study will help for the better understanding of detailed structural dynamics of 12CH2D2. Dideutero-methane 12CH2D2 is unique among all the methane isotopomers because of its asymmetric-top nature. Here, we first report the fine ro-vibrational gas-phase spectra of 12CH2D2 isotopomer in the a-type ν9 (B2-symmetry) fundamental band near 7.8 µm using ultra-sensitive cavity ring-down spectroscopy (CRDS) instrument in the mid-infrared spectral region. We utilized Gaussian 16 to calculate the relevant spectroscopic parameters of 12CH2D2 and subsequently performed the PGOPHER simulation for precise assignments of the fine ro-vibrational lines of 12CH2D2. Further, we conducted the pressure broadening dynamics of 12CH2D2 isotopomer with various foreign gases and accurately determined the pressure broadening coefficients, γi in cm−1 atm−1 [i = He, Ar, N2, Hydrogen mixture(H2 + N2) and zero air] of various transition lines of 12CH2D2.