Mode-selective O-H stretching relaxation in a hydrogen bond studied by ultrafast vibrational spectroscopy.
The ultrafast relaxation of the excited O-H stretching vibration is studied by ultrafast infrared-pump/infrared-probe and infrared-pump/Raman-probe spectroscopy. We demonstrate a 200 fs lifetime of the hydrogen-bonded O-H stretching mode in 2-(2'-hydroxy-5'-methyl-phenyl)benzotriazole (TINUVIN P). O-H stretching relaxation occurs through a few major channels that all involve combination and overtone bands of modes with considerable in-plane O-H bending character. In particular, the mode, which contains the largest O-H bending contribution, plays a prominent role for primary processes of intramolecular vibrational energy redistribution. Theoretical calculations of vibrational energy transfer rates based on a Fermi golden rule approach account for the experimental findings.
Kozich
Valeri
V
Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany.
Dreyer
Jens
J
Ashihara
Satoshi
S
Werncke
Wolfgang
W
Elsaesser
Thomas
T