Raman spectroscopy study of acetonitrile at low temperature

Shuo Zhang; Hongsheng Jia; Mingxing Song; He Shen; Li Dongfei; Li Haibo

doi:10.1016/j.saa.2020.119065

Raman spectroscopy study of acetonitrile at low temperature

Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 5:246:119065. doi: 10.1016/j.saa.2020.119065. Epub 2020 Oct 10.

Authors

Shuo Zhang¹, Hongsheng Jia¹, Mingxing Song², He Shen¹, Li Dongfei³, Li Haibo⁴

Affiliations

¹ Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China.
² College of Information and Technology, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China.
³ Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China. Electronic address: goodldf@126.com.
⁴ Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province, People's Republic of China. Electronic address: lihaibo@jlnu.edu.cn.

PMID: 33096448
DOI: 10.1016/j.saa.2020.119065

Abstract

We report the low-temperature studies of liquid CH₃CN by Raman spectral measurements at ambient pressure with decreasing the temperature from 20 to -196 °C. Detailed internal modes especially the lattice modes analysis revealed that the structural phase transitions of acetonitrile from liquid to solid phase β and solid phase β to solid phase α were occurring at -50 and -60 °C, respectively. Further, the Fermi resonance parameters between the fundamental ν₂ and combination (ν₃ + ν₄) of CH₃CN at different temperatures were calculated based on the Bertran's equations. It is found that the Fermi resonance parameters as a function of temperature become discontinued at -50 and -60 °C, which coincides with discontinuities observed in the Raman shifts of CH₃CN at -50 and -60 °C. The results suggest that the Fermi resonance parameters could be used as an indicator to assess the structural phase transition for CH₃CN under low temperature.

Keywords: Acetonitrile; Fermi resonance; Low temperature; Phase transition; Raman spectroscopy.