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Studies of the formation of non-metallic microclusters and color center type defects in alkali halide clusters.

机译：研究碱金属卤化物簇中非金属微团簇的形成和色心型缺陷。

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摘要

In this dissertation, we have used a laser vaporization cluster source (LVCS) to study the formation of non-metallic clusters, and have applied various laser spectroscopic techniques to study color center type defects in alkali halide clusters. We have demonstrated that laser vaporization of non metallic solids can produce atomic or molecular clusters and cluster ions by direct ejection of fragments from the sample surface. The spectra of cluster ions M(MX){dollar}sbsp{lcub}rm n{rcub}{lcub}+{rcub}{dollar} and X(MX){dollar}sbsp{lcub}rm n{rcub}{lcub}-{rcub}{dollar} formed by vaporizing mixed alkali halide powder samples include virtually no alloyed species, indicating that the observed clusters do not grow from molecular vapor but are instead laser sputtered from the solid in a non-thermal shattering process. In carbon, large clusters result from partial evaporation of ultrafine particles on the sample. We have carried out mass spectroscopy, photodissociation, threshold and above threshold photoelectron spectroscopy studies of alkali halide clusters with color center defects. We have found that the incorporation of a defect may substantially change the cluster's ground state geometry. Particularly, for a stoichiometric alkali halide cluster anion, which has one excess electron and is analogous to an F center, the excess electron can bind inside the cluster in one of several ways that range from being delocalized throughout the cluster or at its surface as a conduction electron, to occupying a crystalline lattice site as though it were a halogen ion.
机译：本文利用激光汽化团簇源（LVCS）研究了非金属团簇的形成，并运用各种激光光谱技术研究了碱金属卤化物团簇的色心型缺陷。我们已经证明，非金属固体的激光汽化可通过直接从样品表面喷射碎片而产生原子或分子簇和簇离子。团簇离子的光谱M（MX）{dollar} sbsp {lcub} rm n {rcub} {lcub} + {rcub} {dollar}和X（MX）{dollar} sbsp {lcub} rm n {rcub} {lcub通过蒸发混合的碱金属卤化物粉末样品形成的}-{rcub} {美元}实际上不包含任何合金物质，这表明观察到的簇不是从分子蒸汽中生长出来的，而是在非热粉碎过程中从固体中被激光溅射的。在碳中，大团簇是由于样品上超细颗粒的部分蒸发而产生的。我们已经对具有色心缺陷的碱金属卤化物簇进行了质谱，光解离，阈值和阈值以上的光电子光谱研究。我们发现缺陷的掺入可能会实质上改变簇的基态几何形状。特别是，对于具有一个过量电子且类似于F中心的化学计量的碱金属卤化物簇阴离子，过量电子可以以多种方式之一结合在簇内，范围从整个簇离解或在其表面处离域为a。传导电子，占据一个晶格位置，就好像它是卤素离子一样。

著录项

  • 作者

    Yang, Yung-An.;

  • 作者单位

    University of Virginia.;

  • 授予单位 University of Virginia.;
  • 学科 Physics Condensed Matter.; Physics Atomic.
  • 学位 Ph.D.
  • 年度 1991
  • 页码 132 p.
  • 总页数 132
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 分子物理学、原子物理学;
  • 关键词

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