Electronic Spectroscopy Of The à − X̃ Transitions Of Jet-cooled Calcium Monoalkoxide Radicals: Spin-vibronic Structure Of Nonlinear Molecules As Candidates For Direct Laser Cooling

Liu, Jinjun

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https://hdl.handle.net/2142/116936 Copy

Description

Title

Electronic Spectroscopy Of The à − X̃ Transitions Of Jet-cooled Calcium Monoalkoxide Radicals: Spin-vibronic Structure Of Nonlinear Molecules As Candidates For Direct Laser Cooling

Author(s)

Liu, Jinjun

Contributor(s)

• Miller, Terry A.
• Riyadh, S. M. Shah
• Sharma, Ketan
• Telfah, Hamzeh
• Paul, Anam C.

Issue Date

2022-06-21

Keyword(s)

Mini-symposium: Benchmarking in Spectroscopy

Abstract

We report a combined experimental and computational study of spin-vibronic structure and transition intensities of the lowest electronic states of nonlinear alkaline earth monoalkoxide (MOR) radicals, including calcium methoxide (CaOCH$_3$), calcium ethoxide (CaOC$_2$H$_5$), and calcium isopropoxide [CaOCH(CH$_3$)$_2$]. Experimentally, laser-induced fluorescence/dispersed fluorescence (LIF/DF) and cavity ring-down (CRD) spectra of the ${\tilde A} {^2 E} – {\tilde X} {^2 A_1}$ electronic transition of CaOCH$_3$ ($C_{3v}$), the ${\tilde A_ 1} {^2 A^{\prime\prime}} / {\tilde A_2} {^2 A^{\prime}} – {\tilde X} {^2 A^{\prime}}$ transition of CaOC$_2$H$_5$ ($C_s$), and the ${\tilde A_ 1} {^2 A^{\prime}} / {\tilde A_2} {^2 A^{\prime\prime}} – {\tilde X} {^2 A^{\prime}}$ transition of [CaOCH(CH$_3$)$_2$] were recorded under jet-cooled conditions. An essentially constant $\tilde A_2 - \tilde A_1$ energy separation for different vibronic levels is observed in the LIF spectrum of each radical, attributed to the spin-orbit (SO) interaction and, in the case of the two $C_s$ molecules, the zero-point-energy-corrected ``difference potential’’. The complete active space self-consistent field (CASSCF) and the coupled-cluster (CC) methods are used to calculate electronic transition energies and vibrational frequencies and to predict parameters governing the spin-vibronic energy level structure and simulate the recorded LIF/DF spectra. The Jahn-Teller (JT), pseudo-Jahn-Teller (pJT), and SO interactions, especially those between the $\tilde A_1 / \tilde A_2$ and the neighboring $\tilde B$ states, induce a number of off-diagonal Franck-Condon (FC) matrix elements leading to additional vibronic transitions. The spin-vibronic Hamiltonian presented in the preceding talk has been employed for the spectral simulation. Computational and experimental results on all three free radicals will be compared, and the implications for future laser cooling experiments will be discussed.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116936&&

DOI

https://doi.org/10.15278/isms.2022.TB09

Copyright and License Information

Copyright 2022 held by the authors

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