Xia Yu, Liu Jiaming, Zhang Xingchu, Zhou Renlong
School of Physics and Information Engineering, Guangdong University of Education, No. 351 Xingang Zhong Road, Guangzhou 510303, China.
J Phys Chem A. 2021 Oct 28;125(42):9338-9345. doi: 10.1021/acs.jpca.1c06523. Epub 2021 Oct 15.
Manipulation of laser-assisted field evaporation taking place at a sub-picosecond time scale relies on a full understanding of the dynamics at a microscopic level. We use first-principles methods to investigate the mechanism of energy absorption and charge draining during fast evaporation of silicon in a high electrostatic field with ultrafast-laser illumination. The results show that laser energy absorption to trigger field evaporation can be described by an effective cross section, which depends on the photon frequency and the static field strength. The cross section is not affected by pulse duration or laser intensity, indicating that the absorption is first-order. It is found that the charge state of the evaporating ion fluctuates due to the collective excitation of electrons. The average charge state does not depend on laser parameters but only on the static field strength, in agreement with experimental observations. Our work provides theoretical insights into the manipulation of modern atom probe tomography and other ultrafast-laser-induced phenomena in high electric fields.
在亚皮秒时间尺度上发生的激光辅助场蒸发的操控依赖于对微观层面动力学的全面理解。我们使用第一性原理方法来研究在超快激光照射下高静电场中硅快速蒸发过程中的能量吸收和电荷耗尽机制。结果表明，触发场蒸发的激光能量吸收可以用一个有效截面来描述，该截面取决于光子频率和静电场强度。该截面不受脉冲持续时间或激光强度的影响，表明吸收是一阶的。研究发现，由于电子的集体激发，蒸发离子的电荷态会发生波动。平均电荷态不依赖于激光参数，而仅取决于静电场强度，这与实验观察结果一致。我们的工作为现代原子探针断层扫描的操控以及高电场中其他超快激光诱导现象提供了理论见解。
