Rovibrational analysis of the [formula omitted] and 2[formula omitted][formula omitted] bands of deuterated formaldoxime (CH2NOD) by high-resolution synchrotron FTIR spectroscopy

Abstract

The high-resolution Fourier transform infrared (FTIR) spectrum of the ν12 band and its hot band 2ν12-ν12 of deuterated formaldoxime (CH2NOD) was recorded at the far-IR beamline of Australian Synchrotron with an unapodized resolution of 0.00096 cm−1 in the 230–350 cm−1 region. A total of 1456 infrared transitions of the ν12 band was fitted using the Watson's A-reduced and S-reduced Hamiltonians in the Ir representation with root-mean-square (rms) deviations of 0.000237 and 0.000262 cm−1 respectively. Furthermore, 483 infrared transitions of the 2ν12-ν12 band were fitted using both A-reduced and S-reduced Hamiltonians in the Ir representation with rms deviation of 0.000186 cm−1. From this rovibrational analysis, the rovibrational constants of the v12 = 1 state up to sextic terms were derived for the first time. The band centers of the ν12 band of CH2NOD were found to be 303.319556(15) and 303.319553(18) cm−1 in the A-reduced and S-reduced Hamiltonians respectively, while band centers of 2ν12-ν12 were 296.620976(67) and 296.620976(67) cm−1 respectively. The rovibrational constants of the ground state of CH2NOD in the A-reduced and S-reduced Hamiltonians were obtained for the first time through the fitting of 608 ground state combination differences (GSCDs) derived from the infrared transitions of the ν12 band, together with 11 previously reported microwave frequencies. The rms deviations of the GSCD fit was 0.000318 and 0.000319 cm−1 in the A-reduced and S-reduced Hamiltonians respectively. Additionally, rotational constants and higher order centrifugal distortion terms of the ground, v12 = 1, and v12 = 2 states of CH2NOD were computed from theoretical anharmonic calculations at two different levels of theory, B3LYP and MP2 with the cc-pVTZ basis set, for comparison with the experimental results. The calculated and experimental rovibrational constants of CH2NOD for the ground, v12 = 1, and v12 = 2 states are in close agreement.