Femtosecond laser plasma x-ray for time-resolved spectroscopy

摘要

High-density plasma created near a solid surface by an intense femtosecond laser pulse emits ultrashort x-ray pulses that are synchronized with the laser pulse. We show the spectral and temporal properties of broadband soft x-rays emitted from a femtosecond laser-produced plasma on a metal surface. The soft x-ray emission was increased about 20-fold by fabricating an array of nanocylinders on a gold surface. We demonstrate the cross-correlation measurement of soft x-ray pulse duration in the femtosecond region by using an optical field-induced ionization process in Kr gas. We used a 10-ps soft x-ray pulse to demonstrate the time-resolved absorption measurement of optically excited silicon near its L_(Ⅱ,Ⅲ) edge. We also employed a picosecond soft x-ray to measure the spatiotemporal evolution of ablated particles in femtosecond-laser-produced aluminum plasma.