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J Phys Chem B. 2011 Feb 10;115(5):1262-7. doi: 10.1021/jp1090697. Epub 2011 Jan 10.

Femtosecond two-dimensional infrared spectroscopy of adenine-thymine base pairs in DNA oligomers.

Author information

1
Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin, Germany.

Abstract

NH and NH(2) stretching excitations of adenine-thymine base pairs in double-stranded DNA oligomers are studied by femtosecond two-dimensional (2D) infrared spectrosopy. The 2D spectra taken for population times of up to T = 1 ps allow for separating the NH stretching mode of thymine from the symmetric and asymmetric NH(2) stretching modes of adenine and to determine their individual line shapes. The spectra demonstrate an essentially homogeneous broadening of the NH stretching band of thymine whereas the NH(2) stretching modes display a pronounced, time-independent inhomogeneous broadening, pointing to disorder in the DNA structure. We observe a (downhill) vibrational energy transfer from the asymmetric NH(2) stretching vibration of adenine at 3350 cm(-1) to the NH stretching mode of thymine at 3200 cm(-1) on a ∼500 fs time scale whereas the inverse (uphill) transfer is negligible.

PMID:
21214277
DOI:
10.1021/jp1090697
[Indexed for MEDLINE]

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