采用开放的梯形三能级原子模型及密度矩阵方程理论，数值模拟了不同参数条件下，双色双光场多光子电离过程中粒子数布居随时间的变化。发现两束激光频率失谐量均为零时，基态、第一、第二共振态粒子数布居随时间呈现振幅减小的拉比振荡，第一共振态布居振荡的频率是基态和第二共振态布居振荡频率的两倍，第二共振态和基态之间可存在较大粒子数布居反转，为实现短波长脉冲相干光输出提供了可能，且激光拉比频率越高，布居振荡频率及粒子数布局反转差值越大。两束激光同步作用于系统，亦有利于粒子数布居反转。

基于光和物质相互作用的密度矩阵方程理论，研究了双光场作用下里德伯原子的瞬态吸收特性。当耦合场较弱时，探测吸收随时间增加到最大值后，再单调递减至零；随着耦合场拉比频率的增加，探测吸收的最大值增大；当拉比频率增加到一定程度时，吸收峰值逐渐减小，吸收随时间延长出现振荡。当耦合场拉比频率取值合适时，出现明显的负吸收现象。通过分析粒子数布居及相干项随时间的演变可知，耦合、探测场共同作用引起的相干项导致了负吸收现象的出现。

以波长可调谐高功率脉冲激光器为激发源，采用共振增强多光子离化（REMPI）光谱技术，对SO2的里德堡态进行实验研究。在420~540 nm波长范围内，得到了与碱金属原子吸收光谱类似的共振增强多光子离化光谱。429.3 nm和452.3 nm处离化峰对应（4+1）共振增强五光子离化，529.4 nm处的离化峰对应（4+2）共振增强六光子离化过程。该离化谱峰序列对应于高激发态F1A2态的np（n=4，5，6）里德堡态序列。对529.4 nm处离化峰的精细扫描表明，该处离化峰呈现为近等间隔的谱峰结构，对应于SO2分子里德堡态4p（0, v2, 0）的共振增强多光子离化光谱序列。实验得到4p里德堡态弯曲振动的基振动角频率Δν2=(387.3±12.4) cm-1。

以Nd:YAG脉冲激光器的基频1064 nm和二倍频532 nm输出为激发源，获得了一种切、斩两用不锈钢刀具材料在300~500 nm波长区间的激光诱导击穿光谱，通过对谱线的归属，发现该不锈钢材料除包含主要元素Fe，还含有为改善材料特性添加的Cr、Ni、Mo、Nb、Cu、V、Ti及微量杂质元素Gd、Zr、Sm、Pm、Nd等。而文献报道的元素C、Si、N，由于其灵敏谱线波长大部分小于300 nm，所以光谱图中未出现明显对应这些元素的谱线。同时发现随激光脉冲能量的增加，等离子体发射谱线的强度、电子温度、电子数密度均增大，将该现象归因于激光能量增加导致的样品烧蚀量增大及电场强度的增加。相同激光能量的条件下，532 nm激光诱导的等离子体具有更高的电子温度和电子密度。

以纳秒Nd:YAG脉冲激光器三倍频(355 nm)激光抽运的染料激光器为激发光源，在484~520 nm波长范围内，采用共振增强多光子离化光谱（REMPI）方法，对H2S分子里德堡序列的能级特性进行了实验研究，得到了谱峰间隔随激光波长增长而呈近二倍变化的两套谱峰序列嵌套而成的规则序列。该谱峰序列对应于H2S分子的里德堡序列激发。依据H2S分子低位激发电子态及里德堡序列的势能高度，可将离化过程确定为五光子4+1离化过程。并将所得到强谱峰序列归属为集结于态的np（n=5,6,7,8）里德堡序列，将弱谱峰序列归属为集结于态的ns（n=6,7,8）里德堡序列。两套序列的量子亏损分别为δ1=0.92和δ2=1.52。所得结果对H2S分子的光学检测及光谱特性研究具有重要意义。

通过求解光和物质相互作用的速率方程，获得了(1+1)共振增强多光子电离过程中电离几率的解析表达式，以该表达式为基础，理论模拟了激光强度、激光脉宽、碰撞弛豫速率等参量对（1+1）多光子电离几率的影响。发现电离几率随激光强度、激光脉宽的增加而增大，到一定程度达到饱和，激光脉宽越大，电离几率随激光强度增加的速率越快，饱和光强值越小。当光强超过饱和值时，电离几率随激光强度的增加围绕饱和值1振荡，电离几率出现大于1的情况，这一有悖于事实的理论结果表明，由于强激光场和物质的相互作用改变了物质系统的能级结构特征，描述光与物质相互作用的速率方程理论不再适用。理论结果还显示，电离几率随碰撞弛豫速率的增加呈线性规律减小，但变化很小，所以样品气压对多光子电离几率的影响可忽略。

Analytic formula of the efficiency of optical-optical double-color double-resonance multi-photon ionization (OODR-MPI) is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the influence of characteristic of the pump and probe laser on the ionization efficiency of (1+2+1) OODR-MPI process is simulated theoretically. It is shown that the pump laser will affect the ionization efficiency by the number control of the molecules excited to the first resonance state. The ionization efficiency is decided by the probe laser directly. Both of the excited molecules and ionization efficiency increase with the intensity and pulse duration of the laser until saturation. It is also found that the longer the delay time of the probe laser to the pump one is, the lower the ionization efficiency would be. The delay time ought to be smaller than the lifetime of the excited molecule in the practical use of the OODR-MPI technique.

The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization (DREMPI) is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2\sum and S2\sum intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.

The optical-optical double-resonant multiphoton ionization (OODR-MPI) spectrum of NO2 molecule in the 460-605 nm wavelength region of the probe photon is presented. The mechanism of the OODR-MPI of NO2 molecule is analyzed. The results show that the resonant features can be assigned to the transitions from the first 3s'sigma'g Rydberg intermediate resonant state to the final np'sigma'u Rydberg series. The ionization pathway is NO2(X2A1)-[3h'nu'1]->3s'sigma'g-[h'nu'2]->np'sigma'u-[h'nu'2 or autoionization]->NO2(+)+e. It is found that the converging potential of the np'sigma'u Rydberg series and the quantum defect of np orbit about NO2 are (78803+-14) cm^(-1) and 0.652+-0.014, respectively. The bending vibration frequency of 5p'sigma'u state is determined also.

The multi-photon ionization spectrum of NO in the wavelength region of 575-680 nm is obtained with an optical parameter generator and amplifier (OPG/OPA) pumped by a picosecond Nd:YAG laser as radiation source. The banded structure of the spectrum indicates that NO molecule is ionized in resonant manner and the peaks of the spectrum are assigned to the transition of NO molecule from the ground electronic state to A2'Sigma' (v'=0,1,2,3), E2'Sigma' (v'=0,1,2), F2'Delta' (v'=0,1,2,3) and H2'Sigma' (v'=0,1,2) intermediate resonant ones. The molecule constants about NO (A2'Sigma', E2'Sigma', F2'Delta', H2'Sigma') states are calculated from the center wavelength of the spectrum. It is also found that owing to the special electron configuration of NO, this molecule does not follow the normal transition selection rule of the diatomic molecule during the multi-photon process.