Picosecond Time-Resolved Fluorescence Depletion Spectroscopy of Fluorene: IVR in the Excited Electronic State

This thesis presents the results of the time resolved study of intramolecular vibrational relaxation in the molecule fluorene. The results represent the first extensive study of a molecule using the technique which we have developed known as the time resolved fluorescence depletion technique. Fluorescence depletion decays and dispersed fluorescence spectra of 19 vibronic features of fluorene are presented. The decays show a progression of dynamic behavior including stationary behavior at low densities of states, quantum beating at intermediate densities, and fast decay of the initially prepared state at high state densities. The data allow us to assign IVR lifetimes to several vibronic levels of fluorene from 27 picoseconds at 1425 cm$\sp{-1}$ of excess vibrational energy to $\leq$10 picoseconds at $\sim$2000 cm$\sp{-1}$. The degree of spectral congestion in the associated dispersed fluorescence spectra is shown to be related to the dynamic behavior of the vibronic features. In addition the effects of intermolecular rotational coherences on the time resolved fluorescence depletion decays of fluorene are explored. With these results we are able to confirm the assignments of the excited state B-values which we have made using rotational band contour simulations.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Kauffman, John Francis

Contributors dc:contributor

• McDonald, J. Douglas

• Chemistry, Physical

Identifier

(UMI)AAI8908729

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70425