Shock-tube study of pressure broadening of the A2∑+ - X2Π (0,0) band of OH by Ar and N2

A rapid-tuning, frequency-doubled ring dye laser was used to make fully-resolved lineshape measurements of OH generated behind reflected shock waves in H2-O2-Ar and H2-O2-N2 mixtures. Values of the collisional linewidth were deduced by fitting the observed lineshapes to Voigt profiles. Lines corresponding to transitions with lower-state rotational quantum numbers ranging from 1.5 to 17.5 in the A2∑+ - X2Π (0,0) band near 307 nm were probed in order to evaluate a possible J″-dependence in the observed broadening. The temperature range investigated was 1400–4100 K. The collisional broadening parameter, 2γ, was measured at fixed temperature and did not exhibit a strong dependence on the rotational quantum number for either Ar or N2. The temperature dependence of 2γ for specific J″-values was measured and fit to a power law with an average value of the temperature exponent of 0.8 for both species.