Basics of Atomic Collision Physics: Elastic Processes
The subject of this and the following two chapters is collisions between electrons, atoms, ions and molecules. We mostly refer here to examples from the particularly productive pioneering period between 1965 and 1990. However, when appropriate, we mention already state-of-the-art research. In Sects. 6.1 and 6.2 we familiarize ourselves with cross sections, and how they are measured, with collision kinematics and its applications. As far as scattering theory is concerned we shall refrain from rigid derivations and prefer easy to understand models. In Sect. 6.3 we introduce elastic scattering and its classical theory while Sect. 6.4 outlines the quantum theory of elastic scattering. A first glimpse on resonances is given in Sects. 6.5 and 6.6 introduces Born approximation for elastic scattering. The two following chapters will go into more depth and treat in particular also inelastic processes. We thus recommend to the reader to study the present chapter with particular care.
KeywordsElastic Scattering Impact Parameter Differential Cross Section Partial Wave Integral Cross Section
Acronyms and Terminology
‘atomic units’, see Sect. 2.6.2 in Vol. 1.
‘Centre of mass’, coordinate system (or frame) (see Sect. 6.2.2).
‘Continuous wave’, (as opposed to pulsed) light beam, laser radiation etc.
‘Differential cross section’, see Sect. 6.2.1.
‘Full width at half maximum’.
‘Integral cross section’, see Chaps. 6 to 8.
‘Jeffreys-Wentzel-Kramers-Brillouin’, semiclassical method to determine scattering phases.
‘Magneto optical trap’, for a typical setup see e.g. Fig. 6.26.
‘R-matrix with pseudo-states method’, advanced quantum mechanical theory for electron scattering.
‘Second order Born approximation’, second order term in the Born series (see Sect. 6.6).
‘Secondary electron multiplier’, see Appendix B.1.
‘Titanium-sapphire laser’, the ‘workhorse’ of ultra fast laser science.
‘Wentzel, Kramers, and Brillouin’, semiclassical method to determine the evolution of the quantum mechanical phase of a wave function as a function of time; basically an approximative method to solve the Schrödinger equation, specifically for the motion of heavy particles.
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