Note on the Quantum Theory of the Reflection of X-Rays

Chandrasekhara Venkata Raman

Chandrasekhara Venkata Raman

Chandrasekhara Venkata Raman, P. Nilakantan

R. Blümel, Thomas M. Antonsen, Bertrand Georgeot +2 more

Recent advances in the theory of the quasiclassical approximation for systems that are chaotic in the classical limit are extended to the case of ray splitting, in particular, to the splitting of an incident ray into a reflected and refracted component at a sharp interface. An instructive example is presented and novel results are found. These include evidence for ray split and periodic orbits in the spectral correlations and a new type of ``scarred'' eigenstate based on combining nonisolated periodic orbits whose quasiclassical contributions have a nontrivial phase from total internal reflection.

Sérgio Luiz Morelhão, Luis Humberto Avanci

By following the trajectories of quantum particles inside a periodic lattice and preserving their classical probabilities for reflection, transmission and absorption at each lattice plane, classical scattering outcomes are obtained. Diffraction phenomena in crystals are reproducible after assigning probability amplitudes to every classical outcome. When applied to X-ray diffraction in reflection geometry, this procedure has provided simple recursive equations to calculated the X-ray reflectivity of crystals with thickness varying since a few atomic layers to infinity. The results are in agreement with the dynamical theory of X-ray diffraction, even when absorption is considered.

Jan Mostowski, Božena Sobolewska

A quantum theory of formation and propagation of superfluorescence and Stokes pulses in samples of small Fresnel numbers is presented. Linearized Maxwell-Heisenberg equations for the system of two-level atoms and a quantized electromagnetic field are solved analytically in the second-order Debye approximation. Under this approximation paths of rays which undergo one reflection from the sides of the sample and those which propagate without reflections are studied. We point out that due to guiding effects, if the Fresnel number is smaller than unity, the contribution from totally reflected rays is not negligible with respect to that from nonreflected rays. This leads to the interference between reflected and nonreflected rays which affects spatial properties of superfluorescence and Stokes pulses. Moreover, as a consequence of guiding effects, the spectral density of light becomes asymmetric and shifted from the atomic resonance frequency.