A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

Olivier Braem; Thomas J. Penfold; Andrea Cannizzo; Majed Chergui

doi:10.1039/C2CP23167K

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

Olivier Braem,^a Thomas J. Penfold,^a^b^c Andrea Cannizzo^a^d and Majed Chergui*^a

* Corresponding authors

^a Laboratory of ultrafast Spectroscopy, ISIC, Ecole Polytechnique Fédérale de Lausanne, Switzerland CH-1015
E-mail: majed.chergui@epfl.ch
Fax: +41 (0)216930365
Tel: +41 (0)216930447

^b Paul-Scherrer Institut, Swiss FEL, CH-5232 Villigen, Switzerland

^c Laboratory of computational chemistry and biochemistry, ISIC, Ecole Polytechnique Fédérale de Lausanne, Switzerland

^d Current address: Institute of Applied Physics, University of Bern, Silderstr. 5, CH-3012 Bern, Switzerland

Abstract

We present a femtosecond broad-band fluorescence up-conversion study of the vibrational relaxation dynamics of two UV chromophores, 2,5-diphenyloxazole (PPO) and para-terphenyl (pTP), pumped with a large excess of vibrational energy (>2000 cm⁻¹). The band narrowing of the transient fluorescence spectrum reflects a biphasic cooling process in a few hundreds of fs and a few ps. In the sub-ps regime, our data suggest a structural rearrangement in the excited state, followed by thermalization of the excess energy. These dynamics affect the fluorescence spectra of PPO and pTP in different ways. In PPO, the damping of a low frequency vibrational wavepacket and a significant sub-ps narrowing of the band characterize the vibrational relaxation. In pTP, the latter is faster and appears as a red shift with distortion of the band in <200 fs.

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Publication details

The article was received on 06 Oct 2011, accepted on 16 Jan 2012 and first published on 17 Jan 2012

Article type: Paper

DOI: 10.1039/C2CP23167K

Citation: Phys. Chem. Chem. Phys., 2012,14, 3513-3519

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A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

O. Braem, T. J. Penfold, A. Cannizzo and M. Chergui, Phys. Chem. Chem. Phys., 2012, 14, 3513
DOI: 10.1039/C2CP23167K
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Physical Chemistry Chemical Physics

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

Abstract

Supplementary files

Publication details

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

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