理论离实验有多远?——用代数方法精确研究双原子分子的完全振动能谱和离解能

本文较系统地简介了双原子分子振动能谱和离解能的研究历史、现状及若干研究方法,重点介绍了孙卫国等最近建立的研究双原子分子完全振动能谱的代数方法(AM)和计算双原子分子离解能的新物理公式。然后应用AM方法和离解能新公式对一批同核和异核双原子分子,以及双原子分子离子电子态的完全振动能谱和离解能进行了研究。结果表明,AM方法和新建立的离解能解析式相结合的理论方法对研究双原子分子及离子的完全振动能谱和离解能是行之有效的、简单经济的物理方法,为实验技术难以精确测量其高激发振动能级或离解能的双原子分子或离子体系提供了获得精确的完全振动能谱和体系离解能的一种理论新方法。     

理论离实验有多远?——用代数方法精确研究双原子分子的完全振动能谱和离解能

本文较系统地简介了双原子分子振动能谱和离解能的研究历史、现状及若干研究方法,重点介绍了孙卫国等最近建立的研究双原子分子完全振动能谱的代数方法(AM)和计算双原子分子离解能的新物理公式。然后应用AM方法和离解能新公式对一批同核和异核双原子分子,以及双原子分子离子电子态的完全振动能谱和离解能进行了研究。结果表明,AM方法和新建立的离解能解析式相结合的理论方法对研究双原子分子及离子的完全振动能谱和离解能是行之有效的、简单经济的物理方法,为实验技术难以精确测量其高激发振动能级或离解能的双原子分子或离子体系提供了获得精确的完全振动能谱和体系离解能的一种理论新方法。     

Li_2部分电子态的完全振动能谱与离解能的精确研究

本文将孙卫国等建立的精确计算双原子分子离解能的解析表达式作为分子振动能级正确收敛的重要物理判据,应用代数方法,进一步研究了重要的碱金属Li2的5个电子态的完全振动能谱和离解能,获得了这些电子态的精确振动光谱常数,同时也得到了包括接近分子离解极限在内的完全振动能谱和与实验值符合得很好的理论离解能.这些计算结果为许多需要这些电子态振动数据的研究领域提供了重要的研究数据.     

双原子分子离解能的精确研究

基于LeRoy与Bernstein的工作,孙卫国等最近建立了计算精确的双原子分子离解能的新解析表达式.应用该公式和最近建立的研究双原子分子精确振动能谱的代数方法(AM),我们研究了一些双原子分子部分电子态的分子离解能,并与实验值进行了比较.研究结果表明,用新解析式获得的精确分子离解能与实验值符合得非常好.该式在理论上提供了获得精确分子离解能的物理新方法.     

800 nm激光作用下碘乙烷的多光子电离解离研究

在800nm飞秒激光作用下对碘乙烷多光子电离解离过程进行了研究,获得了碘乙烷分子的多光子电离飞行时间（MPI-TOF）质谱.光强指数分析表明母体离子主要发生3+3共振增强多光子电离（REMPI）过程.根据部分碎片离子占总离子信号的百分比对激光强度的依赖关系,讨论了碘乙烷的多光子电离解离机制,得出了C₂H₅I分子的多光子电离（MPI）属于母体离子离解阶梯模式.文中分析了母体离子在该波长下主要两条解离通道,其中C-I键的断裂为主要通道.应用高斯03在B3LYP/3-21G基组上计算了两条通道能量的变化,理论进一步验证了实验结果的合理性.     

NaRb分子部分电子态的完全振动能谱与离解能的精确研究

本文应用孙卫国等最近建立的代数方法(AM)和精确计算双原子分子离解能的新解析表达式研究了NaRb分子的X1∑ ,(1)3∑ 和a3∑ 电子态的完全振动能谱和离解能.得到的完全振动能谱既重复了已知的实验能级,又给出了尚没有实验数据的高振动激发能级的正确数值,获得的各电子态离解能精确地符合实验值.这些结果为需要NaRb分子的精确振动能谱和离解能的科学研究提供了重要的数据.     

双原子分子离解能的精确研究

基于LeRoy与Bemstein的工作，孙卫国等最近建立了计算精确的双原子分子离解能的新解析表达式．应用该公式和最近建立的研究双原子分子精确振动能谱的代数方法（AM），我们研究了一些双原子分子部分电子态的分子离解能，并与实验值进行了比较．研究结果表明，用新解析式获得的精确分子离解能与实验值符合得非常好．该式在理论上提供了获得精确分子离解能的物理新方法．     

双原子分子振动能谱与离解能的精确研究

代数方法(AM)的建立解决了实验方法和精确量子力学理论方法难以获得双原子分子的包含最高振动能级在内的所有高阶振动能级的精确数值这一问题.基于LeRoy与Bernstein的工作,孙卫国等又建立了精确计算双原子分子离解能的新解析表达式.应用新公式和代数方法(AM),研究了一些双原子分子部分电子态的振动能谱和分子离解能,获得了与实验值符合非常好的理论结果.该方法在理论上提供了获得双原子分子完全振动能谱和精确分子离解能的物理新方法.     

多原子分子在强红外激光场作用下的多光子光致离解理论

本文从非线性振动理论和单分子化学反应的观点出发,提出一个物理模型用以解释红外激光场作用下的多原子分子瞬时离解现象。我们指出:实验上通常观察到的离解阈值现象与非线性振动中固有的“跳变”过程有着密切的内在联系,以SF₆分子为例,计算并分析了它的离解阈值、频率“红移”和转动补偿等过程,得到在定量上大致与实验现象相符的结果。 关键词：     

用新公式研究K2分子部分电子态的离解能

文章使用孙卫国等人提出的基于微扰理论的代数方法(AM),研究了碱金属K2分子的 、 、 、 、 等五个电子态的离解能;然后使用作者最近提出的新公式计算了这些电子态的离解能,并分别与实验值进行了比较．计算结果表明：使用新公式得到的分子离解能与实验值非常吻合．而对那些还没有离解能实验数据的电子态,该式提供了一种获得其离解能的理论计算方法．     

A saturable absorber for the iodine laser

An absorber for iodine laser pulses has been developed using iodine atoms in the ground state as the absorbing species. The iodine atoms have been produced by dissociation of gaseous molecular iodine in a heated cell. The absorption is easily saturated at moderate energy densities.     

Novel concept of electric discharge oxygen-iodine laser

A novel concept of discharge oxygen-iodine laser (DOIL) is presented. The supersonic DOIL includes a discharge singlet oxygen generator (DSOG) and discharge atomic iodine generator (DAIG). The operation of DSOG is based on a fast mixing of hybrid argon plasma jet of DC electric arc and RF discharge with a neutral molecular oxygen stream. The goal of our effort is achievement of DOIL oscillations by this new discharge technique, which should provide the singlet oxygen yields exceeding 30% at the total pressures higher than 10 torr. The DAIG operation is based on a cw/pulse RF discharge dissociation of iodine donors directly inside a laser iodine injector. This method substitutes the classic dissociation of molecular iodine by energy of singlet oxygen, which saves its energy for laser generation and so can increase the laser efficiency. The laser power could be thus enhanced by up to 25% if this method is employed in a chemical oxygen-iodine laser (COIL) operation, and even 3 times in DOIL without increase in the iodine laser pumping by singlet oxygen.     

Dissociation of molecular iodine in RF discharge for oxygen-iodine lasers

The dissociation of molecular iodine in 40 MHz-RF discharge was studied experimentally. This generation of atomic iodine is aimed at use in oxygen-iodine lasers. The discharge was ignited in a mixture of I₂ + buffer gas fast-flowing through the cylindrical chamber and the discharge products were injected into a supersonic flow of nitrogen. The atomic iodine number density was measured in a low-pressure cavity after mixing with nitrogen and the dissociation fraction was calculated related to the input I₂ flow rate. The dissociation fraction of 46.2% was achieved at 0.22 mmol/s of I₂ and 7 mmol/s of Ar and RF power of 500 W. Argon and helium were used as a buffer gas; discharge stability and dissociation efficiency were better with argon. At the I₂ flow rate corresponding to the operation of a 1 kW chemical oxygen-iodine laser, the dissociation fraction was about 20%. The dissociation efficiency (the fraction of absorbed energy used for the dissociation) significantly decreased with increasing in the specific energy. At a reasonable I₂ flow rate (0.32 mmol/s), the maximum achieved efficiency was 8.5% and the corresponding energy cost was 8.9 eV per dissociating of one I₂ molecule. The input energy of more than 3 kJ per 1 mmol of I₂ is needed for dissociating at least 50% of I₂. The obtained dependencies on the gas flow rates infer a good chance for scaling-up of the tested RF discharge generator for the intended application.     

Proton conductivity in hydrogen iodide-doped iodine

Pure solid iodine doped with hydrogen iodide is found to exhibit proton conductivity with a thermal activation energy ? 0.34 eV. It is suggested that protons are generated via electrolytic dissociation of HI molecules by the dielectric medium of solid iodine.     

一种螺旋型Blumlein线的阻抗特性分析

提出了一种结构紧凑的长脉冲发生器,该发生器的螺旋型Blumlein线由内导体（含磁体）、螺旋型中筒和外导体（含磁体）构成,该结构实现了螺旋型Blumlein线和Tesla变压器的一体化。通过对螺旋型Blumlein线的波传输过程分析,给出了慢波系数、开关闭合电流、用于描述形成线闭合开关处界面上波行为的变量因子等参数的计算公式。采用PIC软件对螺旋型Blumlein线的部分波传输过程进行数值模拟,慢波系数等参数的模拟值与计算值基本相符。进行了恒阻抗负载下螺旋型Blumlein线的原理性实验,实验得到的负载波形与编程计算得到的波形基本吻合。     

Subject index

Lead iodide is known to dissociate under band gap illumination. We investigated the decomposition products from sintered samples by quadrupole mass spectrometry and found that neutral atomic and molecular iodine species desorb from the illuminated surface. The desorption rate was measured as a function of light intensity and surface temperature. Atomic iodine desorption seems to be thermally activated throughout the temperature range (300–500 K), while molecular iodine has that feature only up to 400 K. We performed measurements of the dark and photoconductivity of PbI₂ as functions of temperature and light intensity. Correlations of those results with the photolysis mass-spectrometric data indicate a possible model for the dissociation process. It suggests a diffusion-controlled mechanism of iodine desorption as well as of the dark conductivity, which seems to be ionic in that temperature range. The molecular iodine is apparently formed in surface sites, such as grain boundaries, which have a longer life-time for adsorbed iodine atoms as well as a dominant role in surface electronic conduction.     

流量配比对Coil增益分布影响的数值研究

利用三维CFD技术,通过求解层流Navier-Stokes方程与组分输运方程,对简化后的化学氧碘激光RADICL模型进行数值模拟与分析,结合10种组分和21个基元反应的化学反应模型,对COIL亚声速段横向射流情况下,不同的主副流流量配比对化学氧碘激光器性能的影响进行分析与比较.结果证明,过高或过低的碘分子浓度状态均不利于合理、可观的小信号增益系数产生.存在一个最佳流量配比范围,与之对应的工作状态下,COIL的小信号增益系数会得到显著提高.     

Sub-Doppler molecular-iodine transitions near the dissociation limit (523-498 nm)

A widely tunable and high-resolution spectrometer based on a frequency-doubled Ti:sapphire laser was used to explore sub-Doppler transitions of iodine molecules in the wavelength range 523-498 nm. The wavelength dependence of the hyperfine transition linewidth of iodine was mapped out in this region, and the narrowest linewidth was ~4 kHz near 508 nm. The hyperfine-resolved patterns were found to be largely modified toward the dissociation limit. The observed excellent signal-to-noise ratio should lead to high-quality optical frequency standards that are better than those of the popular 532-nm system.     

Transverse-discharge excitation of the 1.315-μm atomic iodine laser II. Kinetic model

A kinetic model is presented for the transverse-electric-discharge iodine laser which includes electron-impact dissociation, electron attachment and ionization, collisional and radiative deactivation, two- and three-body recombination, and dimerization. Numerical results compare favorably with the experiments of Wong and Beverly (paper I) and Pleasance and Weaver.     

Ab initio studies on ammonium iodine under high pressure

Ammonium iodine(NH_4I) as an important member of hydrogen-rich compounds has attracted a great deal of attention owing to its interesting structural changes triggered by the relative orientations of adjacent ammonium ions. Previous studies of ammonium iodide have remained in the low pressure range experimentally, which we first extended to so high pressure(250 GPa). We have investigated the structures of ammonium iodine under high pressure through ab initio evolutionary algorithm and total energy calculations based on density functional theory. The static enthalpy calculations show that phase V is stable until 85 GPa where a new phase Ibam is identified. Calculations of phonon spectra show that the Ibam phase is stable between 85 GPa and 101 GPa and the Cm phase is stable up to 130 GPa. In addition, ammonium iodine dissociates into NH_3, H_2, and I_2 at 74 GPa. Subsequently, we analyzed phonon spectra and electronic band structures, finding that phonon softening is not the reason of dissociation and NH_4I is always a semiconductor within the pressure range.