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A statistical description of scattering at the quantum level
摘要： Quantum physics is undoubtedly the most successful theory of the microscopic world, yet the complexities which arise in applying it even to simple atomic and molecular systems render the description of basic collision probabilities a formidable task. For this reason, approximations are often employed, the validity of which may be restricted to given energy regimes and/or targets and/or projectiles. Now we have found that the lognormal function, widely used for the probability distribution of macroscopic stochastic events (as diverse as periods of incubation of and recovery from diseases, size of grains, abundance of species, fluctuations in economic quantities, etc.) may also be employed to describe the energy dependence of inelastic collisions at the quantum level (including ionization, electron capture and excitation by electrons, positrons, protons, antiprotons, etc.), by allowing for the relevant threshold energy. A physical interpretation is discussed in this article by analogy with the heat capacity of few-level systems in solid state physics. We find the generality of the analysis to extend also to nuclear reactions. As well as aiding the description of collision probabilities for quantum systems, this finding is expected to impact also on the fundamental understanding of the interface between the classical and quantum domains.
关键词： ionization,electron capture,nuclear reactions,lognormal distribution,excitation,inelastic collisions,quantum physics
更新于2025-09-23 15:21:21
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Measurements, Mechanisms, and Models of Heat Transport || A Macroscopic Model of Blackbody Emissions With Implications
摘要： Measurements of heat transfer in gas, pourable liquids, and nonmetallic solids point to diffusion of radiation being an essential component of heat transport (Chapter 5, Chapter 6 and Chapter 7). Diffusive radiation of heat is a direct outcome of a kinetic theory of gas that incorporates the inelastic nature of collisions (Chapter 5). Long ago, Lommel (1878) associated blackbody (BB) emissions from solids with inelastic losses, and specifically discussed damping of atomic vibrations (Kangro, 1976), but was unable to provide a formula for thermal emissions. His ideas were set aside in the early 1900s. Yet, strong theoretical support for inelasticity exists in the laws of thermodynamics, when these are framed in terms of the macroscopic behavior of light (Chapter 1 and Chapter 5). Fourier’s laws, which describe heat transfer as energy flowing through a medium (Chapter 3), are also consistent with diffusive of radiation explaining conduction in solids.
关键词： blackbody emissions,inelastic collisions,diffusive radiation,heat transfer,thermal emissions,kinetic theory,Fourier’s laws,thermodynamics
更新于2025-09-10 09:29:36