S1 ? Sn and S2 ? Sn absorption of azulene: Femtosecond transient spectra and excited state calculations

Year: 2003

Authors: Foggi P., Neuwahl F.V.R., Moroni L., Salvi P.R.

Autors Affiliation: Dipartimento di Chimica, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy; Lab. Eu. di Spet. non Lineari (LENS), Dipartimento di Fisica, Università di Firenze, Via N. Carrara 1, 50019 Sesto Fiorentino, Firenze, Italy; Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy; INFM, Unitá di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze, Italy

Abstract: The transient spectra of azulene in solution have been measured in the spectral region 600-350 nm at room temperature, pumping into the S1 and S2 states with femtosecond pulses and probing with a delayed femtosecond white light continumm. The spectra are a combination of ground-state bleaching, stimulated emission, and excited-state absorption. The latter component gives a direct information on excited states which may be not active in the ground-state absorption. S1 ? Sn and S2 ? Sn absorptions have been discussed with the help of ab initio calculations of the MCSCF/CAS type with the 6-31G* basis set and including perturbative corrections. The calculated S0 ? Sn, S1,eq ? Sn, and S2,eq ? Sn vertical excitation energies and oscillator strengths are in satisfactory agreement with the experimental results. It has been found that electronic states, weakly active in the ground-state absorption, occur with high intensity in the femtosecond transient spectra, in particular in the energy range 36000-44000 cm-1 above the ground-state energy.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY A

Volume: 107 (11)      Pages from: 1689  to: 1696

KeyWords: Absorption; Absorption spectroscopy; Electron energy levels; Electronic density of states; Ground state; Laser pulses; Probes; Sulfur; Ultrafast phenomena, Azulene; Excited state calculation; Femtosecond pulses; Femtosecond transient spectra, Aromatic compounds
DOI: 10.1021/jp021313e

Citations: 57
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