Surface analysis studies, nuclear

In Table 1, some examples of actual surface analysis studies are given, along with the particular area of nuclear energy... 

CaTi03 - solution analysis, surface analysis and electron microscope studies - implications for Synroc. In Lutze, W. Ewing, R. C. (eds) Scientific Basis for Nuclear Waste Management XII. Materials Research Society Symposium Proceedings, 127, 231-240. 

In the past ten years the number of chemistry-related research problems in the nuclear industry has increased dramatically. Many of these are related to surface or interfacial chemistry. Some applications are reviewed in the areas of waste management, activity transport in coolants, fuel fabrication, component development, reactor safety studies, and fuel reprocessing. Three recent studies in surface analysis are discussed in further detail in this paper. The first concerns the initial corrosion mechanisms of borosilicate glass used in high level waste encapsulation. The second deals with the effects of residual chloride contamination on nuclear reactor contaminants. Finally, some surface studies of the high temperature oxidation of Alloys 600 and 800 are outlined such characterizations are part of the effort to develop more protective surface films for nuclear reactor applications. ... 

This present paper discusses in more detail three separate nuclear-related studies where surface analysis has been used extensively borosilicate glass leaching, surface chloride contamination, and gas phase oxidation of some nickel alloys. 

In Chapter VI, Ohm and Deumens present their electron nuclear dynamics (END) time-dependent, nonadiabatic, theoretical, and computational approach to the study of molecular processes. This approach stresses the analysis of such processes in terms of dynamical, time-evolving states rather than stationary molecular states. Thus, rovibrational and scattering states are reduced to less prominent roles as is the case in most modem wavepacket treatments of molecular reaction dynamics. Unlike most theoretical methods, END also relegates electronic stationary states, potential energy surfaces, adiabatic and diabatic descriptions, and nonadiabatic coupling terms to the background in favor of a dynamic, time-evolving description of all electrons. 

Because the mapping approach treats electronic and nuclear dynamics on the same dynamical footing, its classical limit can be employed to study the phase-space properties of a nonadiabatic system. With this end in mind, we adopt a onemode two-state spin-boson system (Model IVa), which is mapped on a classical system with two degrees of freedom (DoF). Studying various Poincare surfaces of section, a detailed phase-space analysis of the problem is given, showing that the model exhibits mixed classical dynamics [123]. Furthermore, a number of periodic orbits (i.e., solutions of the classical equation of motion that return to their initial conditions) of the nonadiabatic system are identified and discussed [125]. It is shown that these vibronic periodic orbits can be used to analyze the nonadiabatic quantum dynamics [126]. Finally, a three-mode model of nonadiabatic photoisomerization (Model III) is employed to demonstrate the applicability of the concept of vibronic periodic orbits to multidimensional dynamics [127]. 

Mitchell et al. (390) using nuclear reaction analysis (NRA), found 6 = 0.25 for the saturation adsorption of C2H4 on Pt(lll) at 100 K (also see 391). This result has been confirmed by a combined study done with NRA and XPES (392) and by STM (393-395). Furthermore, the value of 8 = 0.25 for C2H4 saturation coverage at low temperature is in agreement with a Monte Carlo simulation of QH4 adsorption on Pt(lll) by Windham et al. (396), who showed that an ensemble of four Pt surface atoms is required to absorb one C2H4 molecule. 

Whether or not the effect can be obtained for a particular element depends on a fortuitous combination of half-life and nuclear energy levels. While many elements have yielded such spectra, the system represented by iron-57 (natural abundance approximately 2%) is the easiest to observe, and excellent results are obtained even at room temperature—hence the interest in the method for studying iron compounds in art and archaeology. While most MES data have been collected with transmission geometry, which requires either thin samples or some sample preparation to achieve thinness, data collection by scattering allows one to achieve the same results with no sample preparation whatsoever—i.e., if the compound to be studied lies at or very near the surface of the material in which the compound occurs. For example, in a sample of a typical iron oxide, the analysis would pertain to a surface layer approximately 0.2 mm deep. 

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