Transient crystalline superlattice generated by a photoacoustic transducer

Abstract

Designing an efficient and simple method for modulating the intensity of x-ray radiation on a picosecond time-scale has the potential to produce ultrafast pulses of hard x-rays. In this work, we generate a tunable transient superlattice, in an otherwise perfect crystal, by photoexciting a metal film on a crystalline substrate. The resulting transient strain has amplitudes approaching 1%, wavevectors greater than 0.002 Å−1, and lifetimes approaching 1 ns. This method has the potential to generate isolated picosecond x-ray bursts with scattering efficiencies in excess of 10%.

Communication: Demonstration of a 20 ps X-ray switch based on a photoacoustic transducer

“…It has also been shown that when the acoustic phonon spectrum is modulated, these sidebands can be enhanced or cancelled 15 . Loether et al proposed a method for switching X-rays based on modulating the acoustic phonon spectrum in a semiconductor by using an optoacoustic transducer 16 . In that study, the X-ray reflectivity from photo-acoustic transducers was studied using a temporal resolution of 50 ps.…”

Stabilizing a high-pressure phase in InSb at ambient conditions with a laser-driven pressure pulse

“…On the time scale of relevance here, only longitudinal expansion takes place, and the strain (σ) can be inferred from the mass density: σ(z, t) = ρ Al,s /ρ Al (z, t) − 1, where ρ Al,s is the density of solid Al, i.e., before the laser pulse. The strain profile in Al at a depth of 300 nm was extracted and an acoustic transmission coefficient from Al to InSb was applied based on the acoustic impedances of the two materials [22,23]. To reproduce the experimental laser conditions, simulations were performed using a range of absorbed fluences in Al similar to the experimental conditions.…”