Charged particle chemistry

Primary cosmic rays (cr) emitted by stars bombard the ISM, including planets such as Earth. The particles are 84 per cent protons and 14 per cent helium nuclei stripped of both electrons called alpha particles the remaining 2 per cent are electrons, heavier nuclei and more exotic particles. 

The particles are usually of extremely high kinetic energy and hence high temperature and are capable of breaking chemical bonds or ionising species by direct impact electron impact dissociation, ionisation and excitation (Equation 5.28)  

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Atmospheric ions are important in controlling atmospheric electrical properties and conmumications and, in certain circumstances, aerosol fomiation [128. 130. 131. 138. 139, 140. 141. 142, 143, 144 and 145]. In addition, ion composition measurements can be used to derive trace neutral concentrations of the species involved in the chemistry. Figure A3.5.11 shows the total-charged-particle concentration as a frmction of... 

Schmelcher PS, Cederbaum LS (1996) Two Interacting Charged Particles in Strong Static Fields A Variety of Two-Body Phenomena. 86 27-62 Schmid G (1985) Developments in Transition Metal Cluster Chemistry. The Way to Large Clusters. 62 51-85... 

Fig. 10 Charge transport is observed in a variety of nucleic acid assemblies over a wide distance regime (3.4-200 A). Shown are examples of nucleic acid structures through which charge transport has been examined a B-form DNA b DNA-RNA hybrids c cross-over junctions and d nucleosome core particles. In all assemblies, the charge transport chemistry is extremely sensitive to the structure of the -stacked nucleic acid bases...

Electrophoresis. Electrophoresis, the movement of charged particles in response to an electric potential, has become very important in biochemistry and colloid chemistry. In the present study an apparatus similar to that described by Burton( M2-M5) was used. A U-tube with an inlet at the bottom and removable electrodes at the two upper ends was half filled with acetone. The a Au-acetone colloidal solution was carefully introduced from the bottom so that a sharp boundary was maintained between the clear acetone and the dark purple colloid solution. Next, platinum electrodes were placed in the top ends of the U-tube, and a DC potential applied. The movement of the boundary toward the positive pole was measured with time. Several Au-acetone colloids were studied, and electrophoretic velocities determined as 0.76-1.40 cm/h averaging 1.08 cm/h. 

The electron itself is frequently used as a primary source of radiation, various kinds of accelerators being available for that purpose. Particularly important are pulsed electron sources, such as the nanosecond and picosecond pulse radiolysis machines, which allow very fast radiation-induced reactions to be studied (Tabata et al, 1991). Note that secondary electron radiation always constitutes a significant part of energy transferred by heavy charged particles. For these reasons, the electron occupies a central role in radiation chemistry. 

Charged particle tracks in liquids are formally similar to cloud chamber or bubble chamber tracks. In detail, there are great differences in track lifetime and observability. Tracks in the radiation chemistry of condensed media are extremely short-lived and are not amenable to direct observation. Also, it must be remembered that in the cloud or bubble chamber, the track is actually seen at a time that is many orders of magnitude longer than the formation time of the track. The manifestation occurs through processes extraneous to track formation, such as condensation, formation of bubbles, and so forth. In a real sense, therefore, charged particle tracks in radiation chemistry are metaphysical constructs. 

Chemical effects from the absorption of charged-particle irradiation were observed almost immediately following the discoveries of X-rays and the electron in the last decade of the nineteenth century. The field, though, remained unnamed until 1942, when Milton Burton christened it radiation chemistry. At present, it has developed into a vigorous discipline embracing radiation physics on one hand and radiation biology on the other. The purpose of this book is to give a coherent account of the development of this field with stress on the fundamental aspects. 

Figure 2. The distribution of ions around a charged particle, showing the tightly bound Stern layer and the diffuse Gouy-Chapman region. Reprinted from [45] Simkiss, K. and Taylor, M. G. Transport of metals across membranes . In Metal Speciation and Bioavailability in Aquatic Systems, eds. Tessier, A. and Turner, D. R., Vol. 3, IUPAC Series on Analytical and Physical Chemistry of Environmental Systems, Series eds. Buffle J. and van Leeuwen, H. P. Copyright 1995 John Wiley Sons Limited. Reproduced with permission...

By its very nature this book is interdisciplinary. The first eleven chapters delineate the fundamentals of radiation physics and radiation chemistry that are common to all irradiation effects. Chapters 12 and 13 deal with specific liquid systems, while Chapter 14 is concerned with LET effects. Chapters 15 to 18 describe biological and medical consequences of photon and charged-particle irradiation. The rest of the book is much more applied in character, starting with irradiated polymers in Chapter 19 and ending with applications of heavy ion impact in Chapter 27. 

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