CH-Stretching Overtone Spectra of cis- and trans-1,3-Pentadiene

Abstract

The room-temperature vapor-phase overtone spectra of cis- and trans-1,3-pentadiene (piperylene) have been recorded in the 5000-17500 cm(-1) region with the use of conventional and intracavity laser photoacoustic spectroscopy. The presence of five nonequivalent olefinic CH bonds and one methyl group in each molecule complicates assignment of the spectra. We have used a harmonically coupled anharmonic oscillator local mode model with one oscillator for each of the nonequivalent CH bonds to calculate the CH-stretching overtone spectra and thus facilitate assignment of the spectra. Our calculated spectra are in good agreement with the observed spectra. The observed high overtone spectra are distinctively different despite the similarity of the two molecules and the numerous and broad transitions.

SH-Stretching Vibrational Spectra of Ethanethiol and tert-Butylthiol

“…Analysis of the experimental spectra yielded oscillator strengths, f, obtained using the following equation 64,65…”

“…Analysis of the experimental spectra yielded oscillator strengths, f , obtained using the following equation , f ⁢ = 2.6935 × 10 − 9 ( K − 1 Torr m cm ) T p l ∫ A ( ṽ ) d ṽ where T is the temperature of the sample, p is the sample pressure in the cell, l is the path length, and A is the absorbance (log 10 ). Because the photoacoustic signal is proportional to absorbance with an unknown constant, absolute absorbance data from the photoacoustic spectra cannot be obtained.…”

Advances in Molecular Structure and Interaction Studies Using Near-Infrared Spectroscopy

“…Thus, the LMM parameters provide bond-specific information somewhat different from that available from normal-mode spectra. The CH stretching higher overtones ( n = 2–6) of alkenes , and naphthalene in the gas phase have been measured and compared with the high-level theoretical calculations of anharmonic spectra. It was shown that the experimental spectra in the higher overtone region are well reproduced by a simple Morse oscillator LMM.…”

Red-light initiated atmospheric reactions of vibrationally excited molecules

“…Absolute oscillator strengths for C-H and O-H stretching overtone vibrations have been investigated using harmonically (HCAO) and anharmonically (ACAO) coupled anharmonic oscillator local mode models. 15,42,45,46,55,[114][115][116][117] Fewer studies have been done on N-H and S-H transitions. 46,[118][119][120][121] In Fig.…”