Table of Contents
Laser Chemistry
Volume 3, Issue 1-6, Pages 203-213

Excitation-Wavelength-Dependent Structure in the Fluorescence Spectra of Bu States of Diphenylpolyenes

Department of Chemistry, University of Pennsylvania, Philadelphia 19104, Pennsylvania, USA

Copyright © 1983 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Experiments have used a tunable picosecond laser to study evolving fluorescence spectra of 1,8-diphenylocta-l,3,5,7-tetraene (DPO) in hexane solution at room temperture. The spectra recorded synchronously (±20 ps) with the irradiation event are analysed in terms of the time-integrated spectra, spectra obtained through a delayed gate, resonance Raman signals and fluorescence from the second excited singlet state. Data are presented to show the dependence of the S2S0 spectrum on the excitation wavelength. The spectra clearly show that vibrational relaxation is incomplete on the timescale of the S2 lifetime. On the other hand, the spectral bands show little tendency at room temperature towards line-narrowing effects. This indicates that the rate of molecular site relaxation is at least comparable to the lifetime of the S2 state under these conditions.