Hydroxyl tagging velocimetry method optimization: signal intensity and spectroscopy

The previously demonstrated nonintrusive time-of-flight molecular velocity tagging method, hydroxyl tagging velocimetry (HTV), has shown the capability of operating both at room temperature and in flames. Well-characterized jets of either air (nonreacting cases) or hydrogen-air diffusion flames (reacting cases) are employed. A 7*7 OH line grid is generated first through the single-photon photodissociation of H2O by a ~193 nm pulsed narrowband ArF excimer laser and is subsequently revealed by a read laser sheet through fluorescence caused by A2(SIGMA)+(vʹ=3) - X2(PI)i(v"=0), A2(SIGMA)+(vʹ=1) - X2(PI)i(v"=0), or A2(SIGMA)+(vʹ=0) X2(PI)i(v"=0) pumping at ~ 248, ~282, or ~308 nm, respectively. A detailed discussion of the spectroscopy and relative signal intensity of these various read techniques is presented, and the implications for optimal HTV performance are discussed.