Mode-selective vibrational redistribution after spectrally selective N-H stretching mode excitation in intermolecular hydrogen bonds.
Mode-selective vibrational redistribution after spectrally selective excitation within the highly structured N-H stretching band of the 7-azaindole dimer was observed by subpicosecond infrared-pump/anti-Stokes Raman-probe spectroscopy. Measurements after relaxation of the N-H stretching vibration indicate ultrafast initial population transfer to vibrations with pronounced N-H bending character. From these modes energy is transferred to modes of frequencies below 1000 cm(-1) on a slower time scale of about 3 ps. Tuning the spectrally narrow infrared excitation to the different substructures of the N-H stretching band influences the distribution of populations between the fingerprint modes. Their relative populations are correlated with the contributions of the modes forming the different coupled combination tones of the N-H stretching band. These results provide experimental support to a Fermi resonance model previously used for simulations of the N-H stretching infrared absorption band shape and insight into relaxation from the initially excited combination bands.
Kozich
V
V
Max-Born-Institut, Max-Born-Strasse 2A, D-12489 Berlin, Germany.
Dreyer
J
J
Werncke
W
W
D002627:Chemistry, Physical / Q000379:methods; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008027:Light; D008962:Models, Theoretical; D009584:Nitrogen / Q000737:chemistry*; D012542:Scattering, Radiation; D012984:Software; D013053:Spectrophotometry / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013997:Time Factors
D006859:Hydrogen; D004247:DNA; D009584:Nitrogen