锰原子激光共振电离

用Ｎｄ：ＹＡＧ泵浦的染料激光进行锰原子三步共振电离。求解了非饱和共振过程速率方程，计算出基态和激发态吸收截面，给出电离效率分别与激发电离速率以及作用时间的变化关系，得到饱和激发电离的流量条件和通量条件，并进行分析讨论。     

铯原子激光共振电离

用Ｎｄ：ＹＡＧ及其泵浦的染料激光进行铯原子三步共振电离。求解了非饱和共振过程速率方程，计算出基态和激发态共振吸收截面，给出电离效率分别与激发电离速率以及作用时间的变化关系，得到饱和激发电离的流量条件和通量条件。     

锡原子激光共振电离

就Ｎｄ：ＹＡＧ泵浦的染料激光进行锡原子三步共振电离，求解非饱和共振过程速率方程。计算共振吸收截面，给出电离效率分别与激发速率、电离速率以及作用时间的关系，得出饱和激发电离的流量条件和通量条件。并进行了讨论。     

三步锂原子激光共振电离计算

用Ｎｄ：ＹＡＧ及其泵浦的染料激光进行锂原子三步共振电离，求解非饱和共振过程的速率方程，计算基态和激发态的共振吸收截面，给出了电离效率分别与激发，电离速率以及作用时间的变化关系，得出饱和激发电离的流量条件和通量条件等，并进行了讨论。     

铊原子激光共振电离研究

用 N d:YAG激光及其泵浦的染料激光进行铊原子三步共振电离。求解了非饱和共振过程速率方程 ,计算出基态和激发态吸收截面 ,给出电离效率分别与激发电离速率以及作用时间的变化关系 ,得到饱和激发电离的流量条件和通量条件。     

铋原子激光共振电离（LRI）跃迁及其电离效率

金属铋（Ｂｉ）是高温超导材料的重要成分，微量铋元素的检测具有广泛的应用价值和重要的基础研究意义，本文就Ｎｄ：ＹＡＧ及其泵浦的染料激光进行铋原子三步共振电离，求解了非饱和共振过程的速率方程，在一些典型实验条件下，计算出基态和激发态的共振吸收截面，给出电离效率分别与二步激发速率，电离速率以及作用时间的变化关系，得出饱和激发电离的流量条件和通量条件等，并进行了一系列讨论．     

参量匹配对双色双共振多光子电离几率的影响

以寻求提高共振增强多光子电离(REMPI)几率的物 理参量为研究目的,采用光和物质相互作用的密度矩阵方程 理论,数值模拟了双色双共振多光子电离过程中泵浦和探测光的参量匹配对电离几率的影响 。结果发现,一定条件下,提高电离 几率的最佳匹配条件是:1) 两束激光强度、脉冲宽度均相等且取值较大; 2) 两束激光无 相 对延迟,输出频率和相应激发跃 迁共振。对1+1+1经探测光双光子共振吸收电离过程,电离几率对探测光更敏感。实际应用 中,若不能保证最佳匹配条件 的实现,应尽量提高探测光的强度、脉冲宽度及近共振吸收;若实验条件不能实现激光频率 和相应跃迁的共振激发,可采 用失谐量互补的两束激光同时作用于系统,通过双光子共振吸收过程提高电离几率。     

钠蒸气中基于钠原子的三种电离机制的研究

本文探寻到钠原子５Ｓ态的双光子共振三光子电离通道,进行了如下实验,在钠原子分子系统中,通过两种方激发式：双光子共振激发（图１中ａ通道所示）和混合共振激发（图１中ｂ通道所示）,将钠原子激发到５Ｓ态,再吸收一个同样频率的光子而电离。进行电离信号检测,第一种激发方式有一个电离峰,对应３Ｓ－５Ｓ双光子共振激发电离;第二种方式有两个电离峰,对应３Ｐ－５Ｓ双光子共振激发电离。这对基于钠原子５Ｓ态电离,提供了新     

钾原子的三种电离机制

自激光出现以来,用激光激发原子和分子,进而使之电离成了研究原子和分子结构及其相互作用过程的重要方法和工具．本文用染料激光激发钾蒸汽,观察钾原子的电离谱,发现了钾原子的三种电离机制：４Ｓ—６Ｓ双光子共振三光子电离、４Ｓ—４Ｄ双光子共振三光子电离和能量积聚诱导的电离． 当激光波长为 ７２８．４ ｎｍ时,钾原子通过第一种过程实现电离．实验测出：随着温度的增加,电离信号逐渐增强,当温度上升到３４０℃ 时,电离谱出现最强值;然后随着温度升高,电离信号逐渐变弱．在温度小于３４０℃ 时,由于温度越高,钾蒸汽中钾原…     

二能级系统共振增强多光子电离过程的理论研究

通过求解二能级系统含时密度矩阵元微分方程，对原子系统在共振和近共振情形下的激光共振增强多光子电离（REMPI）过程中的光电离几率进行了理论推导与分析，得到了光电离几率的解析表达式；研究了氧原子经共振态2p^34p（2＋1）共振增强多光子电离的电离几率与激光脉宽、激光光强及失谐量等参数的关系；给出了共振情形下电离饱和与激光脉宽和激光光强之间的关系式。计算结果表明，对于近共振情形（△较小），激光脉宽和强度一定时，电离几率随着失谐量的增加而减小；当失谐量一定时，光电离几率随光强的增加而增加，光强增加到一定程度时光电离几率出现饱和。对于共振情形（△＝0），激光光强越大，电离几率随脉宽增加的幅度越大。     

3C4--Two-quantum photoionization of Cs and I-

This paper will review briefly a recent experiment which measured the photodetachment probability for I^-ions due to simultaneous absorption of two ruby quanta. We have calculated the two-quantum photoionization rate for atomic cesium as a function of wavelength. The "transition" from the initial state to the bound intermediate state is expressed in terms of oscillator strengths. The second "transition," from these excited valence states into the coulomb continuum is expressed as a cross section. We have observed what appear to be genuine two-photon ionization signals in three cases: 1) near resonance in the10P_{3/2}state using the second-harmonic ofQ-switched ruby, 2) away from resonances, using the 5300 Å second-harmonic ofQ-switched neodymium laser, and 3) away from resonances using the first anti-Stokes line at 5750 Å from ruby-pumped D2gas. Present experiments aim at scanning the interesting range near resonance, e.g., by thermally tuning the ruby.     

High field transport in GaAs,InP and InAs

Calculations of the steady state and transient electron drift velocities and impact ionization rate are presented for GaAs, InP and InAs based on a Monte Carlo simulation using a realistic band structure derived from an empirical pseudopotential. The impact ionization results are obtained using collision broadening of the initial state and are found to fit the experimental data well through a wide range of applied fields. In InP the impact ionization rate is much lower than in GaAs and no appreciable anisotropy has been observed. This is due in part to the larger density of states in InP and the corresponding higher electron-phonon scattering rate. The transient drift velocities are calculated under the condition of high energy injection. The results for InP show that higher velocities can be obtained over 1000–1500 Å device lengths for a much larger range of launching energies and applied electric fields than in GaAs. For the case of InAs, due to the large impact ionization rate, high drift velocities can be obtained since the ionization acts to limit the transfer of electrons to the satellite minima. In the absence of impact ionization, the electrons show the usual runaway effect and transfer readily occurs, thus lowering the drift velocity substantially.     

The influence of a second resonance on the saturationcharacteristics of the four-wave sum mixing

Experimental results are presented, related to the saturation mechanisms of the four-wave sum mixing (4-WSM) generation in Hg when a double resonance enhancement is employed, that is, a two photon resonance to the δ¹S₀ state followed by the δ¹S₀-6p'³D₁ one photon coupling. This coupling is shown to alter the saturation characteristics of the four-wave sum mixing radiation by affecting the two-photon excitation to the δ¹S₀ state, reduce the ionization of the Hg atoms by the incoming radiation and create an absorption window for the generated radiation in a region near the autoionizing state by modifying the linear susceptibility