Idler energy dependence of nonlinear diffraction in X → X + EUV parametric down-conversion

Abstract

The idler energy dependence was investigated for the rocking curve of nonlinear diffraction in parametric down-conversion of X-rays into extreme ultraviolet. The line shape of the rocking curve changed drastically from a nearly Lorentzian peak to a dip as the idler energy decreased. The rocking curve was analyzed using the Fano formula.

Parametric-Down Conversion of X-rays into the Optical Regime

“…The results of the present Letter advance the development of a spectroscopy method for probing valence-electron charges and the microscopic optical response of crystals with atomic-scale resolution. DOI: 10.1103/PhysRevLett.119.253902 Nonlinear interactions of x rays and optical radiation can provide insight into the microscopic structure of chemical bonds, the valence electron density of crystals, and lightmatter interactions at the atomic-scale resolution [1][2][3][4][5][6][7][8][9][10][11]. The high resolution stems from the short wavelengths of x rays, whereas the optical fields interact with the valence electrons.…”

Parametric Down-Conversion of X Rays into the Optical Regime

“…Nonlinear interactions of x rays and optical radiation can provide insight into the microscopic structure of chemical bonds, the valence electron density of crystals, and lightmatter interactions at the atomic-scale resolution [1][2][3][4][5][6][7][8][9][10][11]. The high resolution stems from the short wavelengths of x rays, whereas the optical fields interact with the valence electrons.…”

“…This probe has great potential in the study of microscopic optical properties of materials. Unfortunately, the experimental realization of these ideas is very challenging, and only a few experiments in this direction have been reported [3][4][5][6][7][8][9][10] since they were proposed almost 50 years ago [1]. The experimental observation of parametric down-conversion (PDC) of x rays to optical wavelengths has never been reported.…”

“…It should be noted that the pertinent effect of x rays into extreme ultraviolet (EUV) PDC has been applied already to investigate the optical properties of crystals [3,4,[6][7][8][9][10]. By using this approach, the microscopic linear susceptibility of a diamond crystal with a resolution of 0.54 Å has been extracted from the measurements of the PDC for several atomic planes [4].…”

Recent Progress in X-Ray Nonlinear Optics

“…X-ray PDC is one of the lowest (second) order nonlinear processes, where the pump x-ray photon decays spontaneously into two photons, the x-ray signal photon and the idler photon [2]. After the first observation, several experiments have been reported for x-ray PDC into x-ray [3,4], extreme ultraviolet (EUV) [5,6], and vacuum ultraviolet (VUV) regions [7]. The later case demonstrates one of the most important aspects of x-ray nonlinear optics, that very wide spectral region can participate in the process.…”