Radiative lifetimes of vibrational levels and transition probabilities of spontaneous emissions of the six lowest-lying triplet states of AlN radical

Wei Xing; Deheng Shi; Jinfeng Sun; Zunlue Zhu

doi:10.1016/j.saa.2019.03.045

Radiative lifetimes of vibrational levels and transition probabilities of spontaneous emissions of the six lowest-lying triplet states of AlN radical

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Jun 15:217:77-85. doi: 10.1016/j.saa.2019.03.045. Epub 2019 Mar 19.

Authors

Wei Xing¹, Deheng Shi², Jinfeng Sun³, Zunlue Zhu³

Affiliations

¹ College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China; College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China.
² College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China. Electronic address: scattering@sina.com.cn.
³ College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China.

PMID: 30927574
DOI: 10.1016/j.saa.2019.03.045

Abstract

The potential energy curves of 23 states of AlN radical are calculated to accurately determine the first several lowest-lying singlet and triplet states. The calculations are done using the CASSCF method, which is followed by the valence internally contracted MRCI approach. The rotationless radiative lifetimes of the vibrational levels are approximately 10^-7-10^-8 s for the C³Π, D³Π, and E³Δ states, 10¹-10^-4 s for the A³Σ^- state, and 10^-4-10^-5 s for the B³Σ⁺ state. The origins of the vibronic bands and the radiative lifetimes agree well with the available experimental and other theoretical results. The Einstein coefficients of many vibronic emissions are large for the C³Π-X³Π, C³Π-A³Σ^-, D³Π-X³Π, D³Π-A³Σ^-, and E³Δ-X³Π transitions and therefore, these transitions are strong. The emissions of the E³Δ-D³Π system are so weak that it is difficult to measure them through spectroscopy. The spectral distribution of the vibronic emissions is evaluated for the transitions of 12 pairs of states. In terms of the radiative lifetimes and transition probabilities obtained here, several spectroscopic routines for observing these states via spectroscopy are proposed.

Keywords: Electric dipole moment; Franck–Condon factor; Potential energy curve; Rotationless radiative lifetime; Transition probability.