SPECTRAL SIMULATION TECHNIQUE AND ITS APPLICATION TO HIGH-RESOLUTION LMR SPECTRA OF NITRIC OXIDE

LMR(Laser Magnetic Resonance)光谱技术采用磁场扫描及磁场调制获得顺磁分子吸收谱线，其谱线具有Voigt线型及各不相同的磁场线宽.本文考虑线型理论模型和实验条件，提出了一种实现LMR谱精密仿真的方法，并设计了相应仿真计算程序.对     

高分辨光谱的计算机自动读谱及辅助分析

本文以谱线中心位置在整个谱型中所独有的特性和噪声阈值为依据,提出了一种计算机自动获取谱线中心频率及其相对强度的简便算法,并设计了相应的计算机程序。将该方法和程序应用到具有代表性的由十多条CHF3谱线部分重迭组成的可调远红外实验谱图的预分析,结果表明所获取的谱线中心频率和相对强度与人工获取这些参数初值后经拟合得到的准确结果非常一致,验证了该方法和程序的准确性和有效性,表明其有着广泛的应用前景,可作为处理日益骤增的光谱信息的强有力工具。     

飞秒泵浦-探测实验数据分析

陈述了几种获取飞秒泵浦-探测实验数据中的光解动力学信息的解析物理模型.其中单分量和双分量模型用来解释母体分子的单通道和双通道解离过程,另一个单分量模型用来解释碎片分子的解离或去激发过程.所有模型都结合泵浦-探测实验数据予以解释.     

飞秒泵浦-探测质谱方法研究苯内转换动力学

以飞秒400及266 nm激光脉冲结合泵浦-探测飞行时间质谱方法研究了苯S2态内转换动力学. 400 nm双光子过程将苯分子激发到S2电子态,布居在S2电子态的分子由于能级耦合无辐射弛豫到S1电子态. 通过测定C6H6+讯号强度随泵浦-探测延迟时间的改变,获得苯S2及S1电子态的衰减寿命分别为(48±1)fs及(6.5±0.2)ps, S2态及S1电子态的消激发机理被认为是相应势能面间的锥形交叉引起的内转换.     

Photoionization microscopy of hydrogen atom near a metal surface

We have studied the ionization of Rydberg hydrogen atom near a metal surface with a semiclassical analysis of photoionization microscopy. Interference patterns of the electron radial distribution are calculated at different scaled energies above the classical saddle point and at various atom-surface distances. We find that different types of trajectories contribute predominantly to different manifolds in a certain interference pattern. As the scaled energy increases, the structure of the interference pattern evolves smoothly and more types of trajectories emerge. As the atom approaches the metal surface closer, there are more types of trajectories contributing to the interference pattern as well. When the Rydberg atom comes very close to the metal surface or the scaled energy approaches the zero field ionization energy, the potential induced by the metal surface will make atomic system chaotic. The results also show that atoms near a metal surface exhibit similar properties like the atoms in the parallel electric and magnetic fields.     

15N16O(X2P)高分辨光谱的核超精细结构和L-双分裂分析

从分子核超精细结构和L-双分裂的理论出发, 导出了核超精细结构和L-型双分裂谱线跃迁的简便计算公式. 通过这些公式对观测到的NO(X2P)高分辨光谱进行分析计算, 快速准确地获得了15N16O分子的部分核超精细结构和L-双分裂参数. 这一方法可为新分子谱线的标识和指认提供有效途径及准确参数依据.     

GLOBAL ANALYSIS OF SPECTRA OF THE PO2 RADICAL IN THE GAS PHASE

A global analysis of all available and identified spectra of the PO₂ radical has been performed. In this analysis, the infrared spectra of the ν₃ band, the microwave and far infrared laser magnetic resonance transitions in the ground state are fitted simultaneously to the effective Hamiltonian for asymmetric top molecules. Since the analysis absorbs reliable experimental data extensively, it bears the most precise and most complete set of molecular constants for PO₂. These molecular constants can be used to reproduce the spectra of PO₂ accurately. Attention is also paid to the similarity and difference between PO₂ and NO₂.     

High quality electromagnetically induced transparency spectroscopy of ~(87)Rb in a buffer gas cell with a magnetic field

We have studied the phenomenon of electromagnetically induced transparency(EIT) of ~(87)Rb vapor with a buffer gas in a magnetic field at room temperature. It is found that the spectral lines caused by the velocity selective optical pump effects get much weaker and wider when the sample cell is mixed with a 5-Torr N_2 gas while the EIT signal is kept almost unchanged. A weighted least-square fit is also developed to remove the Doppler broadening completely. This spectral method provides a way to measure the Zeeman splitting with high resolution, for example, the Λ-type EIT resonance splits into four peaks on the D_2 line of ~(87)Rb in the thermal 2-cm vapor cell with a magnetic field along the electric field of the linearly polarized coupling laser. The high-resolution spectrum can be used to lock the laser to a given frequency by tuning the magnetic field.     

Exact quantum defect theory approach for lithium in magnetic fields

We calculate the diamagnetic spectrum of lithium at highly excited states up to the positive energy range using the exact quantum defect theory approach. The concerned excitation is one-photon transition from the ground state 2s to the highly excited states np with π and σ polarizations respectively. Lithium has a small quantum defect value 0.05 for the np states, and its diamagnetic spectrum is very similar to that of hydrogen in the energy range approaching the ionization limit. However, a careful calculation shows that the spectrum has a significant discrepancy with that of hydrogen when the energy is lower than 70cm-1 . The effect of the quantum defect is also discussed for the Stark spectrum. It is found that the σ transition to the np states in an electric field has a similar behavior to that of hydrogen due to zero interaction with channel ns.     

Theoretical simulation of ~(87)Rb absorption spectrum in a thermal cell

In this paper,we present a theoretical simulation of ~(87)Rb absorption spectrum in a thermal cm-cell which is adaptive to the experimental observation.In experiment,the coupling and probe beams are configured to copropagate but perpendicular polarized,making up to five velocity selective optical pumping(VSOP) absorption dips able to be identified.A A-type electromagnetically induced transparency(EIT) is also observed for each group of velocity-selected atoms.The spectrum by only sweeping the probe beam can be decomposed into a combination of Doppier-broadened background and three VSOP dips for each group of velocity-selected atoms,accompanied by an EIT peak.This proposed theoretical model can be used to simulate the spectrum adaptive to the experimental observation by the non-linear least-square fit method.The fit for the high quality of experimental observation can determine valuable transition parameters such as decaying rates and coupling beam power accurately.