Theoretical studies of infrared spectra for the N2-N2O complex: The tunneling effects of fundamental and combination bands

Limin Zheng; Yanshan Tian; Dapeng Yang; Hongli Wang; Lipeng Shi; Rui Zheng

doi:10.1016/j.saa.2019.117199

Theoretical studies of infrared spectra for the N₂-N₂O complex: The tunneling effects of fundamental and combination bands

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Oct 5:221:117199. doi: 10.1016/j.saa.2019.117199. Epub 2019 May 28.

Authors

Limin Zheng¹, Yanshan Tian², Dapeng Yang², Hongli Wang², Lipeng Shi², Rui Zheng³

Affiliations

¹ Computational and Design Center for Low-dimensional Quantum Material, College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China; School of Physics and Electronics, North China University of Water Resources and Electric Power, Zhengzhou 450011, China.
² School of Physics and Electronics, North China University of Water Resources and Electric Power, Zhengzhou 450011, China.
³ School of Physics and Electronics, North China University of Water Resources and Electric Power, Zhengzhou 450011, China. Electronic address: zhengrui@ncwu.edu.cn.

PMID: 31170606
DOI: 10.1016/j.saa.2019.117199

Abstract

This study is a continuation of our previously published research for the N₂-N₂O complex [Journal of Chemical Physics 143 (2015) 154304], and focuses on predicting the quantum tunneling effects of infrared fundamental and combination bands. A new four-dimensional intermolecular potential energy surface (PES) was constructed for the vibrational excited state upon the N₂O ν₁ excitation at the same calculated level with the previous PES of ground state. Compared with the ground state, two equivalent T-shaped global minima are found to be slightly different in both structural parameters and binding energies. Based on the PESs of ground and vibrational excited states, the vibrational shift of infrared spectrum for the fundamental band in the N₂O ν₁ region is determined to be a blue shift of 1.29 cm^-1 for ¹⁴N₂-N₂O, which is in qualitative agreement with the experimentally observed value of 2.233 cm^-1 [Journal of Chemical Physics 140 (2014) 044332]. Furthermore, for the fundamental and disrotation bands, the calculated tunneling splitting is almost the same for the ground and vibrational excited states, so the tunneling effects cannot be observed for these bands using the infrared spectroscopic technique. Nevertheless for the infrared combination bands, our calculated results suggest that the tunneling effects for the torsion and twice disrotation bands are significantly larger, and the predicted infrared spectra display obvious differences for the different sub-states. If the sensitivity of infrared spectrometer is high enough, it is interesting to investigate the quantum tunneling effects experimentally.

Keywords: Fundamental and combination bands; N(2)–N(2)O complex; Quantum tunneling effects.