Radiative, collisional, and predissociative effects in CH laser-induced-fluorescence flame thermometry

摘要

Laser-induced fluorescence of'the CH radical is used to determine the flame-front temperature of an 8-Torr premixed CH_(4)/O_(2) flame. The A ~(2)△-X ~(2)II (0, 0) and B ~(2)∑- -X ~(2)Ⅱ (0, 0) bands give values of 1960 ± 60 and 1920 ± 70 K, respectively. This is an improvement over a previous study that found discrepancies up to 20% between these bands. New rotational-level-dependent transition probabilities are the main reason for this improvement. The weaker off-diagonal bands A-X (0, 1) and B-X (0, 1) yield temperatures of 1930 ± 90 and 1830 ± 100 K, respectively. The influence of rotational transfer on the predissociated levels that have N'> 14 in B ~(2)∑-, ν' = 0 was investigated with fluorescence scans and a statistical power-gap law model of the relaxation; deviations up to 8% in temperature can occur because of this process.