title: Confined breather-type excitation in a quinoidal thiophene after sub-5 fs pulse excitation.
abstract: A quinoidal thiophene molecule which is a prototype of the repeated unit of s-trans-cis-polyacetylene was studied by sub-5 fs spectroscopy. A breatherlike mode modulation of both the amplitude and frequency of the C[Double Bond]C stretching was observed for the first time. It generates two sidebands of 2238 and 700 cm(-1) with a separation of 769 cm(-1) corresponding to the modulation frequency. The latter mode is very close to the C-S-C ring deformation, which indicate that this mode mediates coupling between the breather mode and the C(beta)-C(beta) stretching mode. It was also found that the breather-type excitation has a longer lifetime (2-3 ps) than in all-trans-polyacetylene (50 fs) due to its confinement.
authors.affiliation: Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan. kobayashi@ils.uec.ac.jp
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.forename: Zhuan
authors.initials: Z
authors.lastname: Wang
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Otsubo