Physical review. B, Condensed matter
Ultrashort x-ray pulse propagation through resonant attenuating media
F. N. Chukhovskiǐ, Ulrich Teubner, Eckhart Forster
Abstract
The propagation of ultrashort x-ray pulses through a resonant attenuating two-level atom medium is investigated on the basis of the temporal point-source (the Green-function) formalism. A general case of the small-area pulse (SAP) approximation of a traveling coherent wave is considered. The patterns of the SAP envelope E(t,z) and energy U(z) evolution within the medium are calculated in the cases of incident Lorentzian and exponential pulses and their dependence on the temporal bandwidth ${\mathrm{\ensuremath{\tau}}}_{\mathrm{band}}$ in comparison with the total dissipative relaxation time (lifetime) ${\mathrm{T}}_{2}$ . It is shown that if ${\mathrm{\ensuremath{\tau}}}_{\mathrm{band}}$ is the same order or smaller than ${\mathrm{T}}_{2}$ , the reshaping (oscillations) of the pulse envelope and/or low energy-loss effects occur in accord with the general conclusions pointed out by Crisp [Phys. Rev. A 1, 1604 (1970)] in the case of the SAP for coherent light traveling through a resonant medium. The experimental conditions for the observation of penetration effects of the SAP of x rays are discussed. Based on the theoretical study, it is found that an ultrashort x-ray pulse emitted by an ultrashort laser-produced plasma propagates through thin resonant medium foils with low energy loss.