title: Ultrafast Intramolecular Proton Transfer of Alizarin Investigated by Femtosecond Stimulated Raman Spectroscopy.
abstract: We report time-resolved stimulated Raman spectra of alizarin in DMSO solution with 403 nm excitation. Upon photoexcitation, the intramolecular proton transfer reaction of alizarin occurs in 70-80 fs, which is confirmed by both the population growth and the frequency and bandwidth changes of skeletal vibrational modes of alizarin. Interestingly, the vibrational frequencies of ν(C═C) and ν(C═O) show opposite shifts during the reaction, which may implicate changes in the resonance structure of anthraquinone and the attached carbonyl group. Vibrational relaxation in the potential surface of the proton transferred tautomer of alizarin and the population decay occurring with two distinct time scales were also observed in addition to the solvation dynamics of DMSO solvent molecules.
authors.affiliation: Department of Chemistry and ‡Department of Physics and Photon Science, Gwangju Institute of Science and Technology , Gwangju 61005, Republic of Korea.
authors.forename: Myungsam
authors.initials: M
authors.lastname: Jen
authors.affiliation: Department of Chemistry and ‡Department of Physics and Photon Science, Gwangju Institute of Science and Technology , Gwangju 61005, Republic of Korea.
authors.forename: Sebok
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemistry and ‡Department of Physics and Photon Science, Gwangju Institute of Science and Technology , Gwangju 61005, Republic of Korea.
authors.forename: Kooknam
authors.initials: K
authors.lastname: Jeon
authors.affiliation: Department of Chemistry and ‡Department of Physics and Photon Science, Gwangju Institute of Science and Technology , Gwangju 61005, Republic of Korea.
authors.forename: Shafqat
authors.initials: S
authors.lastname: Hussain
authors.affiliation: Department of Chemistry and ‡Department of Physics and Photon Science, Gwangju Institute of Science and Technology , Gwangju 61005, Republic of Korea.
authors.forename: Yoonsoo
authors.identifier: 0000-0002-7291-232X
authors.initials: Y
authors.lastname: Pang