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High-resolution Doppler spectroscopy of light-dressed states of multi-electron molecules

多电子分子光饰态的高分辨率多普勒光谱

基本信息

批准号：
11640386
负责人：
HISHIKAWA Akiyoshi
金额：
$ 2.3万
依托单位：
Graduate School of Science, The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In order to clarify the role of light-dressed states in the dynamics of a multielectron molecule in intense laser fields, the dissociation processes, O_2^+→O^++O, in intense laser fields (100fs, 〜3×10^<14> W/cm^2) are studied at the laser wavelength of 795 nm and 398 nm on the basis of the momentum imaging maps of the O^+ fragment ions. The covariance map measurements are performed with high momentum resolution to assign securely the dissociation pathways. From the anisotropic momentum distribution of O^+ with respect to the laser polarization direction, the electronic states of O_2^+ are found to be coupled exclusively through parallel transitions in the course of the dissociation process. The released kinetic-energy of O^+ for both 795 nm and 398 nm are interpreted consistently by a sequential coupling model of light-dressed potential curves of O_2^+ in the quartet Π- state manifold.The dispersed fluorescence spectra of NO and O_2 were measured in the spectral range between 300 nm and 700 nm using a spectrometer equipped with a intensified CCD camera. The observed spectra exhibits a number of spectral lines, most of which were assigned to the electronic transition of the higher charged fragment ions, such as N^+, N^<2+>, O^+ and O^<2+>. A high-resolution (〜2 cm^<-1> ) measurement was performed for the N III 3^2P°→3^2S transition at 409.24 nm. The observed spectra show a doublet pattern when the laser polarization is directed towards the spectrometer, which is interpreted as a result of a large released kinetic energy imposed on the N^<2+> fragment ion through the Coulomb explosion of NO.Based on the kinetic energy estimated from the split pattern of the spectra, it was found that the N^<2+> fragment was produced through the Coulomb explosion process, NO^<4+>→N^<2+>+O^<2+>.

为了阐明光装态在强激光场中多电子分子动力学中的作用，基于动量成像图，研究了激光波长795 nm和398 nm下强激光场（100fs，〜3×10^<14> W/cm^2）中的解离过程O_2^+→O^++O。 O^+ 碎片离子。协方差图测量以高动量分辨率进行，以安全地分配解离途径。从O^+相对于激光偏振方向的各向异性动量分布，发现O_2^+的电子态在解离过程中仅通过平行跃迁耦合。 O^+在795 nm和398 nm处释放的动能与四重Π态流形中O_2^+光势曲线的顺序耦合模型一致地解释。使用配备增强CCD相机的光谱仪在300 nm和700 nm光谱范围内测量NO和O_2的分散荧光光谱。观察到的光谱显示出许多谱线，其中大部分归属于较高电荷碎片离子的电子跃迁，例如N^+、N^<2+>、O^+和O^<2+>。在409.24 nm处对N III 3^2P°→3^2S跃迁进行高分辨率（〜2 cm^-1>）测量。当激光偏振指向光谱仪时，观察到的光谱显示出双峰图案，这被解释为通过 NO 库仑爆炸对 N^<2+> 碎片离子施加大量释放动能的结果。根据从光谱分裂图案估计的动能，发现 N^<2+> 碎片是通过库仑爆炸过程产生的， NO^<4+>→N^<2+>+O^<2+>。