2-(-hydroxy--methyl-phenyl)benzotriazole (TINUVIN P).
Vibrational pump/probe schemes: (a) infrared-pump/infrared probe, (b) direct infrared-pump/anti-Stokes Raman probe (pump and probe on the same vibrational transition), and (c) indirect infrared-pump/anti-Stokes Raman probe. The observed mode is populated via IVR after excitation of a different mode.
Infrared spectrum of TIN dissolved in . Solvent infrared lines are subtracted. Inset: absorption spectrum of TIN; the spectral position for Raman probing is indicated by an arrow.
Upper panel: stationary Stokes Raman spectrum of TIN dissolved in cyclohexane . Solvent contributions are subtracted. Lower panels: picosecond infrared-pump/Raman-probe measurements after excitation at in the O–H stretching band. Anti-Stokes difference spectra of TIN in recorded at different delay times.
Femtosecond infrared-pump/infrared-probe spectroscopy of the O–H stretching vibration of TIN excited at . Upper panel: temporal evolution of the probe pulse at (triangles). Solid line: monoexponential fit . Dashed line: cross correlation function (CCF, ). Lower panel: temporal evolution of the probe pulse at (circles). Solid line: monoexponential fit with a constant background .
Resonant infrared-pump/anti-Stokes Raman probe of the vibration at (circles) and (squares) of TIN. Dashed line: cross correlation function (CCF). Solid lines: numerically calculated kinetics (: decay time ; : ).
Time-dependent population numbers of the modes at (a) 1604, 1522, and the spectrally unresolved doublet at and (b) of at 898 and the spectrally unresolved doublet at of TIN. Dashed lines: cross correlation function (CCF). Solid lines: fits with a three level model. Dotted line: simulation of populations with an instantaneous rise (inst. rise) and a decay time of .
(Color) Fingerprint normal modes containing large contributions of local in-plane O–H bending motions.
(Color) Energy level scheme (harmonic scaling) for selective relaxation of the O–H stretching band excitation into fingerprint mode overtones and combination tones. Superimposed to the energy level are Lorentzian line shape functions with (dashed line, total area divided by 2) and (solid line).
(a) Calculated lifetime of the state depending on the homogeneous linewidth (Lorentzian fwhm) of the O–H stretching absorption band. (b) Relative mode populations derived from calculated FGR rates for the relaxation of the state into overtones and combination tones.
Rise and decay times of the modes after O–H stretching excitation.
TIN: Experimental (in ) and calculated [B3LYP/6-31G(d,p)] vibrational frequencies (in ), experimental Raman intensities, assignments, and contribution of O–H bending motion (in percent) to the normal mode.
Transition rates from into overtone and combination bands (excited modes). Hamiltonian matrix elements and (experimental) energy mismatch (all in ), Lorentz factor (in ), and inverse transition rates (in picoseconds) for a Lorentzian of the absorption band.
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