Picosecond investigation of the collisional deactivation of OH A 2Sigma+(v' = 1, N' = 4, 12) in an atmospheric-pressure flame.
The collisional deactivation of the laser excited states A 2Sigma+(v' = 1, N' = 4, 12) of OH in a flame is studied by measurement of spectrally resolved fluorescence decays in the picosecond time domain. Quenching and depolarization rates, as well as vibrational energy-transfer (VET) and rotational energy-transfer (RET) rates are determined. An empirical model describes the temporal evolution of the quenching and VET rates that emerge from the rotational-state relaxation. Fitting this model to the measured 1-0 and 0-0 fluorescence decays yields the quenching and VET rates of the initially excited rotational state along with those that correspond to a rotationally equilibrated vibronic-state population. VET from the higher rotational state (N' = 12) shows a tendency for resonant transitions to energetic close-lying levels. RET is investigated by analysis of the temporal evolution of the 1-1 emission band. The observed RET is well described by the energy-corrected sudden-approximation theory in conjunction with a power-gap law.
Beaud
P
P
General Energy Research, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
Radi
P P
PP
Franzke
D
D
Frey
H M
HM
Mischler
B
B
Tzannis
A P
AP
Gerber
T
T