标题： 探索用于触发超快金刚石石墨化的X射线照射条件 显示英文标题

标题： Exploring x-ray irradiation conditions for triggering ultrafast diamond graphitization

摘要： 超短飞秒X射线脉冲由X射线自由电子激光产生，可以在晶体固体中引发不可逆的结构转变。例如，金刚石的照射可能导致石墨化，并在更高的沉积剂量下导致非晶化。我们在现实实验条件下对辐照金刚石的蒙特卡罗模拟表明，由于光电子从光束焦点的弹道逃逸，用硬X射线光子触发石墨化或其他相变可能具有挑战性。决定性参数是光电子范围与焦束尺寸的比例。对于未来的X射线诱导转变实验，这种在 beamtime 之前的弹道传输专用模拟将是必要的。它们可以预测在何种实验条件下可以实现辐照固体中吸收X射线剂量的期望分布。 显示英文摘要

摘要： Intense femtosecond x-ray pulses produced by an x-ray free-electron laser can trigger irreversible structural transitions in crystalline solids. For instance, irradiation of diamond can lead to graphitization and, at higher deposited doses, to amorphization. Our Monte Carlo simulations of irradiated diamond under realistic experimental conditions demonstrate that triggering graphitization or other phase transitions with hard x-ray photons can be challenging due to the ballistic escape of photoelectrons out of the beam focus. Decisive parameter here is the photoelectron range in proportion to the focal beam size. For future experiments on x-ray-induced transitions, such dedicated simulations of ballistic transport preceding the beamtime will be necessary. They can predict experimental conditions under which the desired distribution of the absorbed x-ray dose in the irradiated solid can be achieved.