title: Ultrafast vibrational dynamics of the DNA backbone at different hydration levels mapped by two-dimensional infrared spectroscopy.
abstract: DNA oligomers are studied at 0% and 92% relative humidity, corresponding to N < 2 and N > 20 water molecules per base pair. Two-dimensional (2D) infrared spectroscopy of DNA backbone modes between 920 and 1120 cm(-1) maps fluctuating interactions at the DNA surface. At both hydration levels, a frequency fluctuation correlation function with a 300 fs decay and a slow decay beyond 10 ps is derived from the 2D lineshapes. The fast component reflects motions of DNA helix, counterions, and water shell. Its higher amplitude at high hydration level reveals a significant contribution of water to the fluctuating forces. The slow component reflects disorder-induced inhomogeneous broadening.
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin, Germany.
authors.forename: Biswajit
authors.initials: B
authors.lastname: Guchhait
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin, Germany.
authors.forename: Yingliang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Siebert
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Elsaesser