title: Femtosecond two-dimensional infrared spectroscopy of adenine-thymine base pairs in DNA oligomers.
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.
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin, Germany.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Szyc
authors.forename: Thomas
authors.initials: T
authors.lastname: Elsaesser
mesh_terms: D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D013055:Spectrophotometry, Infrared; D013941:Thymine / Q000737:chemistry*; D013997:Time Factors; D014732:Vibration
chemical_list: D004247:DNA; D000225:Adenine; D013941:Thymine