title: Femtosecond Raman spectra of cis-stilbene and trans-stilbene with isotopomers in solution.
abstract: Femtosecond stimulated Raman spectra of trans-stilbene (D0), its isotopomers D2, D10, D12, (13)C2 and of cis-stilbene in hexane are measured in the ground (S(0)) and excited (S(1)) electronic states. The ground (13)C2 and excited D12 spectra are presented for the first time; the excited cis-spectra differ substantially from previously published ones. S(1) Raman bands of trans-stilbene are 20 cm(-1) wide corresponding to ~1 ps vibrational dephasing. For cis-stilbene the bands are broadened to 40 cm(-1) reflecting a short excited-state lifetime of 0.3 ps, in agreement with transient absorption data. From a dynamic shift of the 1569 cm(-1) band, pump-induced intramolecular cooling is estimated to be less than 20 K. Many S(1) Raman lines are detected for the first time. Vibrational spectra are calculated at MP2/cc-pVTZ (for S(0)) and XMCQDPT2/cc-pVTZ (for S(1)) levels of theory. Experimental and computational results can be used for a re-evalution of Rice-Ramsberger-Kassel-Marcus (RRKM) predictions for this famous photoisomeration reaction.
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany.
authors.forename: A L
authors.initials: AL
authors.lastname: Dobryakov
authors.forename: I
authors.initials: I
authors.lastname: Ioffe
authors.forename: A A
authors.initials: AA
authors.lastname: Granovsky
authors.forename: N P
authors.initials: NP
authors.lastname: Ernsting
authors.forename: S A
authors.initials: SA
authors.lastname: Kovalenko