arXiv subjects

F. He

Publications and source records attributed to F. He.

38 records · Page 3Linked to original sources

arXiv2011

An in-vacuum diffractometer for resonant elastic soft x-ray scattering

We describe the design, construction and performance of a 4-circle in-vacuum diffractometer for resonant elastic soft x-ray scattering and reflectivity. The diffractometer, installed on the REIXS beamline at the Canadian Light Source, includes 9 in-vacuum motions driven by in-vacuum stepper motors and operates in ultra-high vacuum at base pressure of 2 x10^-10 Torr. Cooling to a base temperature of 18 K is provided with a closed-cycle cryostat. The diffractometer includes a choice of 3 photon detectors: a photodiode, a channeltron and a 2D sensitive channelplate detector. Along with variable slit and filter options, these detectors are suitable for studying a wide range of phenomena having both weak and strong diffraction signals. Example measurements of diffraction and reflectivity in Nd-doped (La,Sr)_2CuO_4 and thin film (Ga,Mn)As are shown.

cond-mat.str-el↗

arXiv2007

Absorbing boundaries in numerical solutions of the time-dependent Schrödinger equation on a grid using exterior complex scaling

We study the suppression of reflections in the numerical simulation of the time-dependent Schrödinger equation for strong-field problems on a grid using exterior complex scaling (ECS) as absorbing boundary condition. It is shown that the ECS method can be applied in both the length and the velocity gauge as long as appropriate restrictions are applied in the ECS transformation of the electron-field coupling. It is found that the ECS method improves the suppression of reflection as compared to the conventional masking technique in typical simulations of atoms exposed to an intense laser pulse. Finally, we demonstrate the advantage of the ECS technique to avoid unphysical artifacts in the evaluation of high harmonic spectra.

physics.atom-ph↗