Internal-conversion and radiative-transition processes among the 1Bu+, 1Bu- and 2Ag- states of all-trans-neurosporene as revealed by subpicosecond time-resolved Raman spectroscopy

The entire Raman spectra of the 1B(u)(-), 1B(u), and 2A(g) states of carotenoid were recorded. for the first time. in all-trans-neurosporene by means of subpicosecond time-resolved Raman spectroscopy using stimulated-Raman process. A sequential internal-conversion processes of 1B(u)(-) --> 1B(u) --> 2A(g) as well as vibrational-relaxation processes in the 1B(u)(-) and 2A(g)(-) states were identified by the use of a key C=C stretching Raman line of each excited state. On the other hand, radiative transitions of 1B(u)(-) --> 2A(g)(-) and 1B(u) --> 2A(g)(-) were identified by the accompanying 2A(g). C=C stretching Raman lines. (C) 2002 Elsevier Science B.V. All rights reserved.