[en] Assessing the mechanisms which govern the distribution, fate, and pathways of entry into biological systems, as well as the ultimate hazards associated with the radon progeny and their secondary reaction products, depends on knowledge of their chemistry. Our studies are directed toward developing fundamental information which will provide a basis for modeling studies that are requisite in obtaining a complete picture of growth, attachment to aerosols, and transport to the bioreceptor and ultimate incorporation within. Our program is divided into three major areas of research. These include measurement of the determination of their mobilities, study of the role of radon progeny ions in affecting reactions, including study of the influence of the degree of solvation (clustering), and examination of the important secondary reaction products, with particular attention to processes leading to chemical conversion of either the core ions or the ligands as a function of the degree of clustering

[en] The evolving chemical and physical form of radon progeny influence their transport to the bioreceptor and the extent to which that receptor can take up these species into various tissues. When first born following radioactive decay processes, the potentially deleterious radon progeny undergo various physical and chemical transformations as they transcend from a highly charged to a neutral state, and interact with various constituents of the environment. These transformations impact on the extent to which the radon progeny become associated with aerosol particles on the one hand, and their ultimate chemical form that is available for uptake in the biosystem, on the other. The program, which originally commenced in 1987, dealt with the basic chemistry and physics of radon progeny and hence impacted on several themes of importance to the DOE/OHER radon program. One of these is dose response, which is governed by the physical forms of the radon progeny, their transport to the bioreceptor and the chemical forms that govern their uptake. The second theme had to do with cellular responses, one of the major issues motivating the work. It is well known that various sizes of ions and molecules are selectively transported across cell membrane to differing degrees. This ultimately has to do with their chemical and physical forms, charge and size. The overall objective of the work was threefold: (1) quantifying the mechanisms and rates of the chemical and physical transformation; (2) ascertaining the ultimate chemical forms, and (3) determining the potential interactions of these chemical species with biological functional groups to ascertain their ultimate transport and incorporation within cells

[en] This constitutes studies designed to provide data for assessing the mechanisms governing the distribution, fate and pathways of entry into biological systems, as well as the ultimate hazards, associated with radon progeny and their secondary reaction products. The chemical and physical state of radon progeny are expected to influence their mobility and reactivity, and mechanisms of transport and entry into biological systems since these depend on processes such as attachment to and/or incorporation with aerosol particles. There is evidence that an appreciable fraction of the progeny are ionized and this program addresses the clustering, growth, and subsequent chemical conversion of these associated species. 2 refs

[en] A major technique for investigating the thermochemical properties of ions and their related clusters is the high pressure drift/mass spectrometer detection technique. A crucial question in this regard is the extent to which ions drifting in an electric field are thermalized. This paper is divided into two parts, one describing some laser techniques which are enabling an investigation of the possible presence of excited ions in a drift field, and secondly, a reporting of some recent findings and trends in the stability of ion clusters of single and mixed constituents

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[en] Closely related to the process of ion induced nucleation is the solvation of ions. In fact, when condensable ligand molecules progressively attach to an ion in large enough number for a phase transformation to occur, a small liquid droplet is formed. While the droplet is not quite an electrolyte because ions of only one sign are present, detailed studies of such phenomenon in the gas phase lead to further elucidation of the molecular interactions analogous to those of ions in the liquid phase. The interrelationship of solvation and nucleation phenomenon is evident, and the purpose of this review is to compare these two processes, point out similarities, differences, present unknowns, and directions for future research. Herein, discussion is confined to the subject of nucleation from the gaseous to the condensed state. Major emphasis is focused on information concerning energetics and structure of small clusters which can be derived from mass spectrometric measurements combined with ab initio semi-empirical quantum mechanical, and electrostatic calculations

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[en] Studies of the structure, stability, electronic properties, and formation kinetics of small clusters provide information useful in furthering an understanding of nucleation processes, the formation and stability of collodial media, and the nature of surfaces. Using mass spectrometry, coupled with various high pressure ion clustering and molecular beam techniques, the details of the primary clustering steps leading to nucleation from the vapor are obtained by direct observation. This paper is devoted to a review of some recent results on these subjects obtained in the authors' laboratory

[en] Studies of the structure, stability, electronic properties, and formation kinetics of small clusters provide information useful in furthering understanding of nucleation processes, liquid state properties, and the nature of surfaces. Using mass spectrometric coupled with various high pressure ion clustering and Stark effect-molecular beam techniques, the details of the primary clustering steps leading to the nucleation of bulk liquid from the vapor are obtained by direct observation. A review of some of the recent results on these subjects is given. (Auth.)