【作者】 杨晓冬；

【导师】 张连水；

【作者基本信息】 河北大学 ， 光学， 2003， 硕士

【摘要】 本工作以超短脉冲(35ps)Nd：YAG激光的三倍频输出(355nm)泵浦光学参量发生／放大器作为激发源，获得了NO分子在420～680nm波长范围内的多光子共振离化光谱。通过对上述离化光谱的分析与归属，确认上述离化谱线分别是以激发态A~2∑~+为中间共振态的2+2共振增强离化、以高激发态F~2Δ、H~2∑、C~2∏、D~2∑为中间共振态的3+1或3+2共振增强离化以及以F~2Δ、H~2∑、E~2∑为中间共振态的4+1共振增强离化谱线；并对离化信号的强度随样品气压的变化关系进行了实验测量，确定NO分子离化光谱的最佳测量气压约为330pa。根据上述中间共振态的振动潜线序列的实验数据，分别计算了各激发电子态的振动基频以及平衡位置的力常数。在此基础上，对于NO分子在2+2和4+1离化过程中所表现出的不同于普通双原子分子的跃迁选择定则进行了较为细致的分析讨论。我们所研究的上述NO分子的激发态都属于里德堡态，其性质与碱金属原子类似，而NO分子的基电子态最外层价电子运动与碱金属原子d轨道电子运动类似，它遵循碱金属原子的双光子与4光子吸收跃迁选择定则。因此NO分子表现出与普通双原子分子不同的跃迁选择定则。为此我们利用双光子荧光激发光谱技术对NO分子所表现出的与普通双原子分子不同的跃迁选择定则进行了实验验证。更多还原

【Abstract】 The resonance-enhanced multi-photon ionization(REMPI) spectrum of NO in the region of 420-680nm is obtained by using Optical Parameter Generator and Amplifier (OPG/OPA) as radiation source. The OPG/OPA was pumped by Nd:YAG (Quantel) laser. According to (he theoretical analysis, the peaks on the REMPI spectrum are ascribed to the intermediate resonant state A2Σ+ F2,H2△,C2Σ,D2Л F2Σ,H2△ and E2Σ. This indicates that the ionization progress of NO is REMPI progress via the intermediate states A2Σ+(2+2), F2Σ,H2△, C2Σ,D2Л(3+1 or 3+2), F2Σ,H2△ and E2Σ(4+1). The relationship between ion signal and laser intensity supports above conclusion also. At the same time, the optimum pressure is determined from the ion signalversus pressure. Based on the experiment, the molecule constants about NO resonant intermediate states are calculated. The experimental results show that the transition from NO ground state to the resonant intermediate state follows special selection rule. The main reason for the special selection rule of NO is that the most excited states (including the A2Σ+,F2Σ,H 2△, C2Л,D2Σ,E2Σ) are Ryderberg type and the ground state configuration of NO is sufficiently appreciated by that of an alkali atom. So the selection rule of NO is analogous to that of alkali atom and different from the usual diatom molecule. The conclusion is further affirmed by the two photon fluorescence excitation spectrum of NO.更多还原