NO分子双光子诱导荧光的自吸收现象

Self-Absorption of NO Fluorescence Induced by Two-Photon

以皮秒Nd:YAG激光器抽运的光学参量发生/放大器为激发光源,获得了在452·4nm波长激光激发下,NO分子的双光子激光诱导色散荧光光谱(LIDFS)。并由此得到了NO分子基电子态的振动基频和振动非谐性系数分别为ω″e=(1904·7±7·3)cm-1,ω″eχ″e=(14·2±1·2)cm-1,ω″ey″e=-(0·0218±0·0091)cm-1。在NO分子双光子LIDFS实验研究中,首次观测到了NO分子强烈的自吸收现象,在较高样品气压条件下,色散荧光光谱图中对应A2Σ(v′=0)→X2Π(v″=0)跃迁的谱线消失。实验结果表明,自吸收现象导致的该跃迁谱线强度的变化,随样品气压、激光场和样品作用区到荧光接收窗口距离的减小而减小。

The two-photon LIDFS of NO excited with 452. 4 nm output of an optical parameter generator and optical parameter amplifier pumped by a Nd：YAG laser was obtained. The vibration frequency and the inharmonic coefficients of the ground electronic state of NO were calculated from the results of the spectral ascription. They are ω″e=（1 904.7±7.3）cm-1,ω″ex″e=（14.2±1.2）cm,ω″ey″e=-（0.021 8±0.009 1）cm^-1 respectively. It was found for the first time that the intensity of the spectral lines departs from the Frank-Condon principle due to the self-absorption of NO molecules. The spectral line of A2∑（v′=0）→X^2∏（v″=0） transition disappears in the fluorescence spectra, But it appears gradually with decreasing the sample pressure and the distance from the laser-gas interaction volume to the receiving window. All of these provide an important reference for monitoring NO by the technique of laser-induced fluorescence.