Femtosecond optical Kerr gate fluorescence spectroscopy for ultrafast relaxation processes

We have developed the optical Kerr gate fluorescence spectroscopy with a su bpicosecond time resolution as a new spectroscopic tool to investigate ultr afast relaxation processes of materials. We have used solid glasses as the Kerr media to obtain the subpicosecond time resolution. The typical Kerr ef ficiency and the instrumental response function of the system are 5% and si milar to 250 fs, respectively. The method has been applied to measure the u ltrafast internal conversion from S-2 to S-1 state of beta-carotene in n-he xane solution as the first demonstration. The lifetime of the S-2 state has been determined to be 220 fs. (C) 2000 Elsevier Science B.V. All rights re served.