Hard X-ray transient grating spectroscopy on bismuth germanate

摘要: Optical-domain transient grating (TG) spectroscopy is a versatile background-free four-wave-mixing technique that used to probe vibrational, magnetic and electronic degrees of freedom in the time domain1. The newly developed coherent X-ray free-electron laser sources allow its extension regime. X-rays offer multiple advantages for TG: their large penetration depth allows probing bulk properties materials, element specificity can address core excited states, short wavelengths create excitation gratings with unprecedented momentum transfer spatial resolution. Here, we demonstrate TG hard range at 7.1 keV. In bismuth germanate (BGO), non-resonant generates optical phonons detected as function by diffraction an pulse. This experiment demonstrates ability materials paves way ultrafast techniques using probes involving nanoscale periods. A four-wave mixing range. diamond phase beam path creates periodic pattern on sample via Talbot effect. response probed