High-resolution Fourier transform spectra of CH2D2: The Fermi-interacting vibrational bands ν8(B2), ν4 + ν9(B2) and 2ν9(A1), ν3 + ν4(A1)

First Predictions of Rotationally Resolved Infrared Spectra of Dideuteromethane (12CH2D2) From Potential Energy and Dipole Moment Surfaces

“…Rovibrational infrared spectra of 12 CH 2 D 2 have been the subject of several investigations both at low and high resolution. − , However, this molecule has been much less studied than the major isotopologue 12 CH 4 . The very clear polyad structure of CH 4 due to the remarkable relation between stretching and bending harmonic frequencies, namely ω 1 ≈ ω 3 ≈ 2ω 2 ≈ 2ω 4 , is broken by the double substitution H → D and thus does not appear for 12 CH 2 D 2 .…”

“…Under these conditions, a derivation of appropriate effective spectroscopic models for full experimental data reduction is a very complicated issue. This could explain that ro-vibrational modeling of experimental spectra is only partly available at low and medium energy ranges. − Complete rotationally resolved analyses are known to be very laborious and are yet missing for many bands.…”

“…The latter one contained 47 adjusted parameters including harmonic frequencies ω i , anharmonic x ij constants and eight coupling parameter, and the root-mean-squares deviation of the vibrational fit was 0.76 cm –1 . Though there exists a substantial amount of work concerning the study of line positions, ,− , no systematic intensity measurements or analyses in the infrared have been published for 12 CH 2 D 2 up to now. In this work, we present variational predictions of 12 CH 2 D 2 spectra involving both line positions and ab initio line intensities.…”

“…Better understanding of the methane dynamics would benefit of detailed studies of exited ro-vibrational states of low-symmetry isotopologue CH2D2 as much additional information can be extracted from spectra compared to its symmetric-top and spherical-top isotopic counterparts. , However, high resolution spectra for the “mother molecule” are generally much more investigated and ro-vibration parameters are better determined on larger wavenumber range than those of isotopic species . For low-lying vibrational bands of CH 2 D 2 there exists many experimental studies and spectra analyses, − but this is in contrast with a limited knowledge of line intensities, except for measurements and calculations of vibrationally induced permanent dipole moment. , Information on line parameters of CH 2 D 2 is totally missing in HITRAN , and in other specialized spectroscopic databases , as well.…”

High resolution Fourier transform spectroscopy of CH2D2in the region 2350–2650 cm−1: the bands ν5+ ν7, 2ν9, ν3+ ν4, ν3+ ν7and ν5+ ν9

“…High resolution studies of the first overtone and combination bands have been reported in refs. [33][34][35][36] where the bands 5 , n 5 þ n 9 and 2n 3 were analyzed. It should be mentioned, however, that ro-vibrational transitions with J up to J max ¼ 9 were assigned for the bands included in refs.…”