Transient Raman observations of heme vibrational dynamics in five-coordinate iron porphyrins

Joseph J Loparo; Christopher M Cheatum; Mark R Ondrias; M.Cather Simpson

doi:10.1016/S0301-0104(02)00924-2

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Transient Raman observations of heme vibrational dynamics in five-coordinate iron porphyrins

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Transient Raman observations of heme vibrational dynamics in five-coordinate iron porphyrins

Joseph J Loparo, Christopher M Cheatum, Mark R Ondrias and M.Cather Simpson

Chemical physics, Vol.286(2), pp.353-374

2003

DOI: 10.1016/S0301-0104(02)00924-2

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Abstract

Transient resonance Raman spectroscopy has been used to study vibrational dynamics in five-coordinate, high-spin Fe II octaethyl porphyrin with a 2-methyl imidazole axial ligand. Vibrational populations of the porphyrin ground electronic state were probed by examining Stokes and anti-Stokes Raman scattering as a function of incident laser flux using ∼10 nanosecond pulses in resonance with the Soret electronic transition. Within a single pulse, each molecule goes through several excitation-decay cycles, building up a non-equilibrium, excited vibrational energy distribution that is exquisitely sensitive to the vibrational mode lifetimes and to the incident laser flux. A kinetic model illustrates these ideas and provides strong support for the interpretation of the results. The flux dependence of the Raman intensities, positions and linewidths suggests that ν 3 and ν 4 act as “bottleneck” vibrational states, while ν CH and ν 7 couple more effectively to the environment.

Details

Title: Subtitle: Transient Raman observations of heme vibrational dynamics in five-coordinate iron porphyrins
Creators: Joseph J Loparo - Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
Christopher M Cheatum - Department of Chemistry, University of New Mexico, Albuquerque, NM 87135, USA
Mark R Ondrias - Department of Chemistry, University of New Mexico, Albuquerque, NM 87135, USA
M.Cather Simpson - Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
Resource Type: Journal article
Publication Details: Chemical physics, Vol.286(2), pp.353-374
Publisher: Elsevier B.V
DOI: 10.1016/S0301-0104(02)00924-2
ISSN: 0301-0104
Language: English
Date published: 2003
Academic Unit: Chemistry; Liberal Arts and Science Admin
Record Identifier: 9984216709102771

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