The Ohio State University Department of Chemistry Femtosecond Mid-infrared Spectroscopy Of Pyrimidine DNA Bases: Intramolecular Vibrational Redistribution, Vibrational Cooling And Excited State Photophysics Chris T. Middleton, Patrick M. Hare † , Kristin I. Mertel and Bern Kohler † Current address: University of Notre Dame Radiation Laboratory, Notre Dame, Indiana, 46556
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The Ohio State UniversityDepartment of Chemistry Femtosecond Mid-infrared Spectroscopy Of Pyrimidine DNA Bases: Intramolecular Vibrational Redistribution,
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The Ohio State University Department of Chemistry
Femtosecond Mid-infrared Spectroscopy Of Pyrimidine DNA Bases: Intramolecular Vibrational Redistribution, Vibrational Cooling And Excited State Photophysics
Chris T. Middleton, Patrick M. Hare†, Kristin I. Mertel and Bern Kohler
† Current address: University of Notre Dame Radiation Laboratory, Notre Dame, Indiana, 46556
Nucleic acid bases
UV initiated photochemistry can lead to mutations and skin cancer
(photocarcinogenesis)
Pyrimidine Photophysics in Solution
Hare, et al., JPCB 110 18641 (2006)
Acetonitrile H2O
UV/Visible Transient Absorption of 1CHU
NH
O
ON
1-cyclohexyluracil
(1CHU)
- both the lifetime of 1nπ* state and the triplet quantum yield are dramatically reduced in protic solvents
- broad electronic absorption spectra of 1nπ* and triplet strongly overlap
Transient mid-IR Spectra of 1CHU
*
Kinetics of 1nπ* band
a Hare, et al., JPCB 110 18641 (2006)
- solvent dependence of lifetime confirms assignment to 1nπ*
- no ground state modes between 1750 cm-1 and ~3000 cm-1
- excited state vibrational spectra provide information about the electronic structure, gauge of theoretical calculations
Thymine Triplet Dynamics
excellent agreement between short and long time spectra