Zizak G, Petrucci G A, Stevenson C L, Winefordner J D
Appl Opt. 1991 Dec 20;30(36):5270-5. doi: 10.1364/AO.30.005270.
Two optical double-resonance pump-probe techniques were used to determine the ground-state rotational population distributions of OH in an acetylene-air flame when a saturating laser beam is tuned to the Q(1)4 transition of the (0, 0) Sigma-II band. The saturated absorption technique is based on the detection of absorption by a probe laser under conditions of saturation with a pump laser and no saturation. In the fluorescence technique, a probe laser is scanned through the (1, 0) band, while a saturating pump laser, tuned to the (0, 0) band, is on or off. We found that approximately 15% of the total population of the ground state was transferred to the excited state. Perturbation of the rotational population distribution was greater for rotational levels close to the directly excited laser-coupled level. The rotational energy transfer rate in the ground state was somewhat greater than in the excited state. The assumption of the balanced cross-rate model was verified as a means of determining the absoslute OH number density with adequate accuracy.
当一束饱和激光束调谐到（0, 0）Σ-II带的Q(1)4跃迁时，使用两种光学双共振泵浦-探测技术来确定乙炔-空气火焰中OH基态的转动布居分布。饱和吸收技术基于在泵浦激光饱和而探测激光不饱和的条件下对探测激光吸收的检测。在荧光技术中，探测激光扫描（1, 0）带，而调谐到（0, 0）带的饱和泵浦激光开启或关闭。我们发现，基态总布居数的约15%被转移到了激发态。对于接近直接受激激光耦合能级的转动能级，转动布居分布的微扰更大。基态的转动能量转移速率略大于激发态。验证了平衡交叉速率模型作为以足够精度确定绝对OH数密度的一种方法。
