Torsion–Rotation Energy Levels and the Hindering Potential Barrier for the Excited Vibrational State of the OH-Stretch Fundamental Band ν1of Methanol

Anharmonic spectra of methanol and silanol: A comparative study

“…Although these five modes have a pure movement description in all the cases, deuteration in OH implies a slight difference in the value of the anharmonic frequencies of the CH stretching modes and vice versa (see Tables 1, 2, and S1). These results can be considered as coupling effects among such modes, in agreement with previous works [40][41][42][43][44][45][46][47][48][49][50].…”

“…2. Described experimental couplings [40][41][42][43][44][45][46][47][48][49][50] among CH and OH stretchings and the torsion movement in methanol, along with the anharmonic interaction between two normal modes [38], are well reproduced theoretically by this method. 3.…”

“…Additionally, a set of harmonic force constants has been calculated at ab initio and DFT levels of theory [38] and an ab initio anharmonic force field was also developed [39]. Methanol exhibits a large amplitude motion, i.e., the internal rotation (torsion) of the OH group with respect to the CH 3 group, and a number of recent experimental and theoretical works focus on the analysis of this normal mode and its coupling with some other vibrational modes, e.g., CH stretching modes [16,[40][41][42][43][44][45][46][47][48][49][50].…”

Doppler-limited CW infrared cavity ringdown spectroscopy of the ν1+ν3 OH+CH stretch combination band of jet-cooled methanol

“…5) were made by testing the strongest observed lines for the required ground state combination differences [34]. The observed subband origins of A K ¼ 0 0 and E K ¼ 0 0 are 6529.11 cm À1 and 6527.14 cm À1 , respectively, which are close to the values of 6530.04 and 6527.15 cm À1 predicted by adding the corresponding subband origins of the m 1 and m 3 fundamentals [27,29]. To highlight CO 2 reference line, the slit jet was turned off in a small wavenumber region around the reference line.…”

“…These results are compared to the high resolution analysis of the m 3 (symmetric CH stretch) and m 1 fundamentals [27][28][29][30][31] to provide insight into the nature of torsionvibration coupling in methanol.…”