High-resolution Laser Spectroscopy And The Zeeman Effect: Dibenzothiophene

Baba, Masaaki

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https://hdl.handle.net/2142/116762 Copy

Description

Title

High-resolution Laser Spectroscopy And The Zeeman Effect: Dibenzothiophene

Author(s)

Baba, Masaaki

Contributor(s)

Nakayama, Naofumi

Issue Date

2022-06-23

Keyword(s)

Structure determination

Abstract

For planar aromatic hydrocarbons, intersystem crossing to the triplet state is expected to be very slow according to El Sayed's rule\footnote{M. Baba, N. Nakayama, et al., J. Chem. Phys. {\bf 130}, 134315 (2009).}\footnote{M. Baba, J. Phys. Chem. A {\bf 115}, 9514 (2011).}. The fluorescence lifetime in the S$_1$ state of dibenzothiophene is remarkably shorter compared with the analogous molecules such as dibenzofuran. Pratt et al. suggested that the main fast process was intersystem crossing on the basis of the result of high-resolution laser spectroscopy\footnote{L. Alvarez-Valtierra, John T. Yi, and David W. Pratt, J. Phys. Chem. A {\bf 113}, 2261(1990).}. We observed the high-resolution spectrum in the external magnetic field in order to confirm the contribution of the triplet state. However, no change has been found in the spectrum up to 1.0 Tesla, indicating that the intersystem crossing is slow and is not the main process for the fluorescence decay in the S$_1$ state of dibenzothiophene. It should be noted that the spectral feature of the S$_1$ $\leftarrow$ S$_0$ 0$_0^0$ band of dibenzothiophene is $b$-type, whereas that of dibenzofuran is $a$-type. The relatively faster decay is considered to be the result of different character in the $S_1$ elecronic state. Several electronic excited states are expected to be located in the lower energy region\footnote{M. Baba, T. Katori, M. Kawabata, S. Kunishige, and T. Yamanaka, J. Phys. Chem. A {\bf 117}, 13524 (2013).}. Ab initio theoretical calculation of B3LYP/6-311G+(2d,p) accurately reproduced the experimental values of rotational constants and excitation energy. The S$_1$ state has been assigned to $^1A_1$, which is consistent with the fact that the S$_1$ $\leftarrow$ S$_0$ transition is $b$-type.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116762

DOI

https://doi.org/10.15278/isms.2022.RL12

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Copyright 2022 held by the authors

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