title: Identification of four rotamers of m-methoxystyrene by resonant two-photon ionization and mass analyzed threshold ionization spectroscopy.
abstract: We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S1← S0 electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm(-1), and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm(-1) for these isomeric species. Most of the observed active vibrations in the electronically excited S1 and cationic ground D0 states involve in-plane ring deformation and substituent-sensitive bending motions. It is found that the relative orientation of the methoxyl with respect to the vinyl group does not influence the vibrational frequencies of the ring-substituent bending modes. The two dimensional potential energy surface calculations support our experimental finding that the isomerization is restricted in the S1 and D0 states.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Yanqi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Sheng Yuan
authors.initials: SY
authors.lastname: Tzeng
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Vidya
authors.initials: V
authors.lastname: Shivatare
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Kaito
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Wen Bih
authors.initials: WB
authors.lastname: Tzeng
mesh_terms: D002412:Cations; D003198:Computer Simulation; D007536:Isomerism; D008956:Models, Chemical; D015394:Molecular Structure; D013057:Spectrum Analysis / Q000379:methods; D020058:Styrene / Q000737:chemistry*; D014732:Vibration
chemical_list: D002412:Cations; D020058:Styrene