Abstract book - Prof. Per Jensen, Ph.D. - Bergische Universität ...

58 Poster session, D11Rotationally-resolved High-resolution Laser Spectroscopy of theS 1 ←S 0 Electronic Transition of Naphthalene and Cl-naphthaleneShunji Kasahara 1 , Kenichiro Kanzawa 2 , and Kohei Tada 21 Molecular Photoscience Research Center, Kobe Univ., Japan, kasha@kobe-u.ac.jp;2 Graduate School of Science, Kobe University, Japan, 101s219@stu.kobe-u.ac.jpKasahara S.Kanzawa K.Tada K.Rotationally-resolved high-resolution fluorescence excitation spectra of the 0-0 band 1and several vibronic bands 2 up to the excess energy of 3068 cm -1 for naphthaleneS 1 ←S 0 transition were measured by crossing a single-mode UV laser beamperpendicular to a collimated molecular beam. Several thousands rotational lines wereobserved and assigned for each band except 3068 cm -1 band, and these molecularconstants were determined in high accuracy. By comparing the observed and calculatedtransition energy from the determined molecular constants, the local energy shifts werefound and identified as originating from Coriolis interaction in the higher energy bands.Additionally, we have observed the change of the spectra with magnetic field. The magnitude ofthe observed Zeeman splitting is very small, and it was mainly observed for the levels oflow K a and its magnitude was increasing in proportion to J for given K a . It indicates themagnetic moment is along to c-axis (out of plane) and originates from an electronicangular momentum induced by J-L coupling between the S 1 and S 2 states. 3We have also observed the rotationally resolved high-resolution fluorescence excitationspectra and the Zeeman effect of the 0-0 band for 2-Cl naphthalene S 1 ←S 0 transition.More than 4500 lines were observed and assigned for 0-0 band without any energy shift,and the molecular constants were determined in high accuracy, which are goodagreement with the ones reported by Plusquellic et. al. 4 The magnitude and J, K-dependences of the observed Zeeman splittings are similar to the ones of naphthaleneS 1 ←S 0 transition. It suggests the main radiationless process is not intersystem crossingeven for the 2-Cl naphthalene. Recently, we also measured the high-resolutionfluorescence excitation spectra of 0-0 band for 1-Cl naphthalene S 1 ←S 0 transition. Therotational lines were not resolved because the fluorescence lifetime is shorter than theone of 2-Cl naphthalene.References[1] D. L. Joo, R. Takahashi, J. O’Reilly, H. Katô, and M. Baba, J. Mol. Spectrosc., 215,155 (2002).[2] K. Yoshida, Y. Semba, S. Kasahara, T. Yamanaka, and M. Baba, J. Chem. Phys.,130, 194304 (2009).[3] H. Katô, S. Kasahara, and M. Baba, Bul. Chem. Soc. Jpn., 80, 456 (2007).[4] D. F. Plusquellic, S. R. Davis, and F. Jahanmir, J. Chem. Phys., 115, 225 (2001).