Picosecond near-infrared excited transient Raman spectra of β-carotene in the excited S2 state: Solvent effects on the in-phase C=C stretching band and vibronic coupling

Picosecond time-resolved Raman spectra of beta-carotene in the excited S-2 (1B(u)(+)) state have been obtained in resonance with its near-infrared transient absorption. The Raman band due to the in-phase C=C stretching mode of beta-carotene in the S-2 state has been observed at about 1550 cm(-1). The solvent effects on this band are discussed in comparison with the previous results on the corresponding bands in the ground S-0 (1A(g)(-)) state and the excited S-1 (2A(g)(-)) state. (C) 2010 Elsevier By. All rights reserved.