Relaxation and anharmonic couplings of the O-H stretching vibration of asymmetric strongly hydrogen-bonded complexes.
We present infrared transient grating measurements of complexes of formic acid with pyridine and pyrazine at four excitation frequencies within the broad proton-stretching band. These experiments investigate the mechanism of the line broadening of the O-H stretching vibration. The transients show coherent oscillations that decay within a few hundred femtoseconds and population relaxation on two time scales. We fit the data using a simple model of three coupled oscillators that relax via sequential kinetics through an intermediate state. Based on this model, we conclude that the coherent oscillations result from superpositions of Fermi-resonance-coupled states involving formic acid overtone and combination states.
Gündoğdu
Kenan
K
Chemistry Department, The University of Iowa, Iowa City, Iowa 52242, USA.
Bandaria
Jigar
J
Nydegger
Michael
M
Rock
William
W
Cheatum
Christopher M
CM
D001665:Binding Sites; D003198:Computer Simulation; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009991:Oscillometry / Q000379:methods*; D010100:Oxygen / Q000737:chemistry*; D014732:Vibration
D017665:Hydroxyl Radical; D006859:Hydrogen; D010100:Oxygen