Quantum mechanical model for nuclear resonant forward scattering using synchrotron radiation

摘要

A quantum mechanical model for forward scattering of synchrotron radiation from nuclear-resonant matter is developed using perturbation theory in the frequency domain.Fourier transformation of the solution results in a plane-wave packet that describes the emitted radiation as viewed in the time domain.The solution provides a microscopic picture of the nuclear resonant processes in which the photons undergo multiple scattering from the resonant nuclei beform reaching the detector.The various "paths" to the detector are coherent when one does not consider emission with recoil or conversion electron processes.In this way it is seen that the "speed-up" effect is essentially a consequence of the fact that the double scattering process is 180 deg out of phase with the single scattering process.It is also seen that the "dynamical beating" is a consequence of the fact that,for sufficiently resonantly thick samples,the triple scattering process,which is in phase with the single scattering process,dominants the double scattering process at later times.The model is easily generalized to include the phenomenon of quantum beats.