title: Observation of the Ring-Puckering Vibrational Mode in Thietane Cation.
abstract: We have measured the high-resolution vibrational spectra of a thietane (trimethylene sulfide) cation in the gas phase by employing the vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopic technique. Peaks in the low-frequency region of the observed MATI spectrum of thietane originate from a progression of the ring-puckering vibrational mode (typical in small heterocyclic molecules), which is successfully reproduced by quantum-chemical calculations with 1D symmetric double-well potentials along the ring puckering coordinates on both the S0and D0states, the ground electronic states of neutral and cation of thietane, respectively. The values of the interconversion barrier and the ring-puckering angle on the S0state, the parameters used for the quantum-chemical calculations, were assumed to be 274 cm-1and 26°. The barrier and the angle on the D0state, however, are found to be 48.0 cm-1and 18.2°, respectively, where such small barrier height and puckering angle for the cation suggest that the conformation of thietane cation on the D0state should be more planar than that of the thietane neutral.
authors.affiliation: Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University , Chuncheon 24341, Korea.
authors.forename: Yu Ran
authors.initials: YR
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Sogang University , Seoul 04107, Korea.
authors.forename: Chung Bin
authors.initials: CB
authors.lastname: Park
authors.affiliation: Department of Chemistry, Sogang University , Seoul 04107, Korea.
authors.forename: Jiye
authors.initials: J
authors.lastname: Hwang
authors.affiliation: Department of Chemistry, Sogang University , Seoul 04107, Korea.
authors.forename: Bong June
authors.initials: BJ
authors.lastname: Sung
authors.affiliation: Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University , Chuncheon 24341, Korea.
authors.forename: Hong Lae
authors.initials: HL
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University , Chuncheon 24341, Korea.
authors.forename: Chan Ho
authors.identifier: http://orcid.org/0000-0003-4440-6240
authors.initials: CH
authors.lastname: Kwon