Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Phys Rev Lett. 2012 May 25;108(21):217402. doi: 10.1103/PhysRevLett.108.217402. Epub 2012 May 23.
We used photon pulses from an x-ray free-electron laser to study ultrafast x-ray-induced transitions of graphite from solid to liquid and plasma states. This was accomplished by isochoric heating of graphite samples and simultaneous probing via Bragg and diffuse scattering at high time resolution. We observe that disintegration of the crystal lattice and ion heating of up to 5 eV occur within tens of femtoseconds. The threshold fluence for Bragg-peak degradation is smaller and the ion-heating rate is faster than current x-ray-matter interaction models predict.
我们使用自由电子激光的光子脉冲来研究石墨从固态到液态和等离子态的超快 X 射线诱导转变。这是通过等容加热石墨样品并在高时间分辨率下通过布拉格和漫散射同时探测来实现的。我们观察到晶格的解体和高达 5 eV 的离子加热在几十飞秒内发生。布拉格峰降解的阈值通量更小，离子加热速率比当前的 X 射线物质相互作用模型预测的更快。
