Abstract
We investigated the ultrafast internal conversion of all- trans - -carotene through time-resolved absorption and fluorescence spectroscopy under same experimental conditions. The lifetime of 1Bu + state was determined to be 210 fs. Based on the analysis which involves four energy levels, 1Ag ; , 2Ag ; , 1Bu ; and 1Bu + , we obtained the spectral shape of the transient absorption bands which correspond to the transitions from the vibronic levels ( l =1, 2) of the 2Ag ; state to higher excited states and from the 1Bu + and/or 1Bu ; state to higher excited states in a wide wavelength range of 400-1000 nm.