The Nucleation of Supersaturated Vapors

这项研究的目的是为了更好地了解成核过程，并使我们能够做出准确的定量预测。研究将在三个有点不同但互补的调查领域：离子诱导成核，金属蒸汽成核和均匀成核。p.i.开发了一种测量离子诱导成核速率的新方法，其中所有重要变量（过饱和、温度和离子密度）都是准确已知的，并且都可以很容易地改变。将重复对正壬烷和1-己醇的初始测量，以降低它们的不确定度，优化条件并将它们扩展到更大的过饱和范围和几个温度。更复杂的物质，如具有四极矩或高极化率的物质（如CS2， CC14）的研究也将进行。第二个主要焦点将是金属蒸气的均匀成核。金属在其稀蒸气状态是非金属的，导致团簇大小依赖于非金属转变。金属的成核研究不仅使人们能够在远低于临界温度的温度下研究这种现象（因此在密度变化本质上是不连续的温度下），而且还将检验成核理论在一类与迄今为止研究过的任何物质都截然不同的物质上的有效性。重点将是该研究小组和德国马尔堡菲利普斯大学由F. Hensel教授和H. Uchtmann博士领导的一个研究小组的共同努力。第三个重点将是继续努力了解均质成核过程。这将包括对各种物质在10-6至101核厘米-3秒-1速率范围内的研究。由汽相到液相的相变由成核作用起着关键作用，种类繁多。

The goal of this research is to provide a better understanding of nucleation processes, and to allow us to make accurate quantitative predictions. The research will be in three somewhat different but complementary fields of investigation: ion induced nucleation, nucleation of metal vapors, and homogeneous nucleation. The P. I. has developed a new method for measuring the ion induced nucleation rate in which all the important variables (supersaturation, temperature, and ion density) are accurately known and all can be readily changed. Initial measurements on n-nonane and 1-hexanol will be repeated to decrease their uncertainty, optimize conditions and extend them to a wider range of supersaturations and to several temperatures. Studies of more complex substances such as those with quadropole moments or high polarizabilities (e.g. CS2, CC14) will also be made. A second major focus will be the homogenous nucleation of metal vapors. Metals in their dilute vapor state are nonmetallic, resulting in a cluster size dependence of the nonmetal transition. Nucleation studies of metals not only will enable one to study this phenomena at temperatures far below the critical temperature (and thus at temperatures where the change in density is essentially discontinuous), but also will test the validity of nucleation theories on a class of substances very different from any studied until now. The focus will be a joint effort of this research group and a research group at Phillips University in Marburg, Germany headed by Prof. F. Hensel and Dr. H. Uchtmann. A third focus will be continued efforts on understanding homogeneous nucleation processes. This will include studies on various substances over a wide range of rates, 10-6 to 101 nuclei cm-3 s-1. Phase change form vapor to the liquid phase by nucleation plays a key role in a wide variety.