Symes D R, Hohenberger M, Henig A, Ditmire T
The Texas Center for High Intensity Laser Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
Phys Rev Lett. 2007 Mar 23;98(12):123401. doi: 10.1103/PhysRevLett.98.123401. Epub 2007 Mar 21.
We report on measurements of ion energy distributions from hydrogen clusters irradiated by intense laser pulses of duration 40 and 250 fs. Contrary to the predictions of a simple Coulomb explosion model, we observe a pronounced spatial anisotropy of the ion energies from these explosions with the highest energy ions ejected along the laser polarization direction. The origin of the anisotropy is distinct from that previously seen in clusters of high Z atoms such as Ar and Xe. Furthermore, a measured increase in H+ ion energy when longer, lower intensity pulses are employed suggests that multiple-pass, vacuum heating of the cluster electrons is important in the deposition of energy by the laser.
我们报告了关于持续时间为40飞秒和250飞秒的强激光脉冲辐照氢团簇时离子能量分布的测量结果。与简单库仑爆炸模型的预测相反，我们观察到这些爆炸产生的离子能量存在明显的空间各向异性，能量最高的离子沿激光偏振方向射出。这种各向异性的起源与之前在诸如氩和氙等高Z原子团簇中所观察到的不同。此外，当使用更长、强度更低的脉冲时测得的H⁺离子能量增加表明，团簇电子的多程真空加热在激光能量沉积中很重要。
