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Updated: Jan 22, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Cation Vibrations of 1-Methylnaphthalene and 2-Methylnaphthalene through Mass-Analyzed Threshold Ionization
Sheng Yuan Tzeng1, Vidya S Shivatare1, Wen Bih Tzeng1
1Institute of Atomic and Molecular Sciences , Academia Sinica , P.O. Box 23-166, 1 Section 4, Roosevelt Road , Taipei 10617 , Taiwan.
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.
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