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High-resolution Raman spectroscopy of ν2 and associated hot bands of 13CH12CH: global analysis of the anharmonic resonances†
Article first published online: 3 FEB 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Volume 44, Issue 5, pages 746–751, May 2013
How to Cite
Martínez, R. Z., Bermejo, D., Lonardo, G. D. and Fusina, L. (2013), High-resolution Raman spectroscopy of ν2 and associated hot bands of 13CH12CH: global analysis of the anharmonic resonances. J. Raman Spectrosc., 44: 746–751. doi: 10.1002/jrs.4247
- Issue published online: 10 MAY 2013
- Article first published online: 3 FEB 2013
- Manuscript Accepted: 17 DEC 2012
- Manuscript Revised: 12 DEC 2012
- Manuscript Received: 5 NOV 2012
- Ministry of Science and Innovation. Grant Number: FIS2009-08069
- stimulated Raman spectroscopy;
- high-resolution spectroscopy;
- stimulated Raman pumping;
- anharmonic resonances
The Raman spectrum of the 13CH12CH molecule in the region of its ν2 vibrational band was recorded at a resolution of 2.6 × 10−3 cm−1 and analyzed. Several Q branches were observed and identified, corresponding to the ν2 fundamental and the associated hot bands ν2 + ν4 – ν4, ν2 + ν5 – ν5, ν2 + 2ν4 – 2ν4 and 2ν2 – ν2. The usual normal modes of vibration in acetylene, with the symmetric (ν1) and antisymmetric (ν3) CH stretchings, the CC stretching (ν2), the degenerate trans (ν4) and cis (ν5) bendings were adopted. All the spectra were obtained using the experimental technique of quasi-continuous stimulated Raman spectroscopy. The fundamental ν2 band and the ν2 + ν4 – ν4 and ν2 + ν5 – ν5 hot bands were recorded at room temperature, while ν2 + 2ν4 – 2ν4 was recorded at a temperature of 355 K. Finally, the spectrum of the 2ν2 – ν2 band was recorded at 170 K using a Raman-Raman double resonance technique in which a stimulated Raman pumping process is used to populate a single rotational level of the v2 = 1 state, prior to the spectroscopy stage. A 15 ns delay between pump and spectroscopy is introduced to allow partial collisional relaxation of the rotational population of v2 = 1 among rotational levels. The assigned Raman transitions and several previously observed infrared bands have been simultaneously fitted in order to derive a set of deperturbed molecular parameters, including the quartic anharmonic coupling coefficients K1,255 and K3,245. The ro-vibrational pattern of the stretching and stretching-bending combination states and an accurate description of the anharmonic resonances in this molecule have been obtained. Copyright © 2013 John Wiley & Sons, Ltd.