Cation Vibrations of 1-Methylnaphthalene and 2-Methylnaphthalene through Mass-Analyzed Threshold Ionization Spectroscopy

Sheng Yuan Tzeng; Vidya S Shivatare; Wen Bih Tzeng

doi:10.1021/acs.jpca.9b03756

Cation Vibrations of 1-Methylnaphthalene and 2-Methylnaphthalene through Mass-Analyzed Threshold Ionization Spectroscopy

J Phys Chem A. 2019 Jul 18;123(28):5969-5979. doi: 10.1021/acs.jpca.9b03756. Epub 2019 Jul 9.

Authors

Sheng Yuan Tzeng¹, Vidya S Shivatare¹, Wen Bih Tzeng¹

Affiliation

¹ Institute of Atomic and Molecular Sciences , Academia Sinica , P.O. Box 23-166, 1 Section 4, Roosevelt Road , Taipei 10617 , Taiwan.

PMID: 31287683
DOI: 10.1021/acs.jpca.9b03756

Abstract

Vibrationally resolved cation spectra of 1-methylnaphthalene (1MN) and 2-methylnaphthalene (2MN) were obtained using the two-color resonant two-photon mass-analyzed threshold ionization (MATI) spectroscopy. MATI spectra were obtained through ionization via several intermediate vibronic levels. Due to hindrance effect, no spectral features related to methyl torsion were observed in the MATI spectra of 1MN. By contrast, most of the in-plane ring deformation vibrations of the 2MN cation were found to couple with methyl torsion because of its small internal rotational barrier. These experimental findings were well supported by our theoretical calculations.