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1.
2.
Summary The onset of CO2 laser-induced breakdown has been observed by irradiating several polyatomic species (SiH4, NH3, hydrocarbons, fluorohydrocarbons) at a wavelength resonant with an IR active vibration. Primary fragmentation and subsequent
ion and radical secondary reactions have been monitored detecting the spontaneous luminescence with a gateable optical multichannel
analyser. The resonant laser-induced processes can be of importance in etching reactors where hydrocarbons and fluoro-hydrocarbons
are commonly used, as well as in laser chemical vapour deposition reactors for the production of sinterable Si3N4 and SiC powders. 相似文献
3.
大气压空气中的流注放电有广泛的理论和应用研究价值,包括雷电机理、输变电系统空气绝缘理论以及材料表面改性等.流注是一个快速发展的强电离区域,在传播过程中存在着一种重要的特点—分支现象.光电离为正流注发展提供必要的自由电子,且实验结果表明分支特征与流注头部的光电离速率密切相关.本文基于新的流注分支判据,采用了粒子网格单元与蒙特卡罗碰撞相结合(PIC-MCC)的三维放电模型(Pamdi3D)进行数值仿真验证.为了研究光电离速率对正流注分支的影响,仿真了毫米尺度间隙针-板电极正流注发展,系统研究了不同光电离参数的影响.当减小氮气-氧气比例、光子吸收截面或光电离效率系数后,流注均更早地出现分支现象.这些计算结果表明大气压空气中流注头部光电离速率的降低将导致其发生分支的概率更高. 相似文献
4.
利用国家同步辐射实验室合肥光源的真空紫外同步辐射,使NO分子和Ar原子混合物的超声分子束发生光电离,测量了Ar,NO和异类团簇Ar·NO的光电离效率谱. 在谱中,在与Ar原子的共振线对应的能量区域(11.5—12.0 eV)观察到一个强的类共振结构. 这个结果表明,在异类团簇Ar·NO的内部,稀有气体Ar原子的激发能转移到与它接触的分子NO上,使分子NO发生电离.
关键词:
Ar·NO团簇
同步辐射
光电离
能量转移 相似文献
5.
M. Gutowski I. Dabkowska J. Rak S. Xu J.M. Nilles D. Radisic K.H. Bowen Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):431-439
The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with
maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a
π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT)
from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of
uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated
glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the
BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the
damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the
standard Watson-Crick pairing scheme.
Received 6 April 2002 Published online 13 September 2002 相似文献
6.
The 3s–np photoionization processes of the ground state 2P1/2 and the metastable state 2P3/2 of Ar5+ are investigated using our recently developed relativistic R-matrix code, where the interactions between the bound states and the continuum states are included. Both resonance positions and the oscillator strengths are in much better agreement with the absolute experimental measurements by Wang et al.[Wang J C, Lu M, Esteves D, Habibi M, Alna’washi G and Phaneuf R A 2007 Phys. Rev. A 75 062712] with a resolution of 80 meV than their theoretical results. The contributions of the two experimental unresolved transitions are distinguished in our calculations, which show that the transitions from the ground state also make significant contributions to some resonances. Our theoretical results are also in good agreement with the measurements for the first resonance with a higher resolution of 20 meV. 相似文献
7.
采用光电离探测方法,对钐原子奇宇称束缚激发态进行了系统研究.通过设计三条不同的激发路径, 采用共振激发方式,先将钐原子分三步从基态激发到不同的束缚激发态,然后采用光电离手段对其进行探测. 通过对第三步激发光的波长进行大范围的扫描,在同一能域内获得了三组不同的光谱. 通过比对三条路径所得到的三组光谱,不仅精确确定了大量奇宇称束缚激发态的能级位置, 而且还获得了相应跃迁的相对强度的信息.最后,通过运用三条不同的激发路径的选择定则, 还确定了上述能级的总角动量.
关键词:
钐原子
束缚激发态
奇宇称
光电离探测 相似文献
8.
Imprints of molecular orbitals using photoelectron angular distribution by strong laser pulses of circular polarization 下载免费PDF全文
We theoretically investigate the strong-field ionization of H+2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron's angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron's angular distribution are split into two parts if the photoelectron energy is sufficiently high. 相似文献
9.
10.
In different regimes of exposure of metals to pulsed laser radiation, we show the role played by the liquid-drop phase formed from the target material in a laser-induced erosion plume due to bulk vaporization, in the dynamics of this plume. For some metals, the ranges of power densities of the acting laser radiation, at which the condensed-phase particles influence the passage of laser radiation to the target surface, have been determined experimentally. The mechanism of realization of a low-threshold breakdown has been revealed. 相似文献