High density collection of molecular ion clusters and their photoexcitation dynamics

分子离子簇的高密度收集及其光激发动力学

基本信息

批准号：
07454190
负责人：
NISHI Nobuyuki
金额：
$ 4.99万
依托单位：
Okazaki National Research Institutes (1996-1997)Kyushu University (1995)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

In order to study electronic states and dynamics of highly condensed molecular ion clusters, we designed a molecular beam apparatus with a soft-landing ion deosition and IR and UVabsorption spectrometers. A molecular beam generated from liquid droplets by adiabatic Big-Bang explosion is directly injected against 10-inch diffusion pump. Ions are extracted perpendicular to the beam axis, mass-selected, decelerated, and gently imbedded in a rare gas matrix. As atest experiment, benzene cations are deposited in argon matrices at 4 K.Contamination of the background neutral benzene was so little that after 10 hour deposition we can detect the neutrals by UV absorption spectrometry. The electronic spectrum of benzene cation showed that the electronic orbitals of argon atoms around the cation is highly distorted and polarized by the cation. The high dnsity deposition process was accompanied with a big difficulty without any codeposition of negative ions. Frequent explosive ablation of the new surface layrs was observed during the deposition. It is necessary to design a natural negative ion deposition mechanism in a chamber.We also observed a charge hopping phenomenon in benzene trimer cations after vibrational excitation of a C-H stretching motion of an ionic molecule. The excitation of an isotopic mixture (C_6H_6) ^+ (C_6D_6)_2 resulted in the fragmentation yielding (C_6D_6)_2^+ and [ (C_6D_6) (C_6H_6) ]^+ with a ratio of 1 : 2. This is a statistical limit suggesting the hopping occurs sufficiently faster than the dissociation process. The observed line-widths of the C-H stretching bands showed sectral shifts dependent on the position of the charged molecules in the cluster and also on the masses of the neighboring molecules. Rather broad line-widths indicates that the relaxation is of the order of 100-150fs.

为了研究电子状态和高度冷凝分子离子簇的动力学，我们设计了一个具有软陆离子DE定位以及IR和UVABS吸附光谱仪的分子束设备。直接注入了10英寸扩散泵，直接注入了由绝热大爆炸爆炸产生的分子束。将离子垂直于梁轴提取，质量选择，减速并在稀有气体基质中轻轻嵌入。作为Atest实验，苯阳离子在4 k处沉积在氩矩阵中。背景中性苯的污染物较少，以至于10小时沉积后我们可以通过紫外吸收光谱法检测中性。苯阳离子的电子光谱表明，阳离子周围的氩原子的电子轨道被阳离子高度扭曲和极化。高DNSITY沉积过程伴随着很大的困难，而没有任何负离子的代码。在沉积过程中观察到新表面层的频繁爆炸性消融。有必要在腔室中设计天然的负离子沉积机制。我们还观察到在离子分子的C-H伸展运动振动激发后，苯三聚体阳离子中的电荷跳跃现象。同位素混合物的激发（C_6H_6）^+（C_6D_6）_2导致分裂产量（C_6D_6）_2^+和[（C_6D_6）（C_6D_6）（C_6H_6）]^+的比例为1：2。这是一个统计上的限制，这是一个统计的限制。 C-H伸展带的观察到的线宽度显示，构件移位取决于带电分子在簇中的位置以及相邻分子的质量。相当广泛的线宽度表明，放松的阶段为100-150F。