Nonequilibrium band mapping of unoccupied bulk states below the vacuum level by two-photon photoemission.
Nonequilibrium band mapping of unoccupied bulk states below the vacuum level by two-photon photoemission.
复制标题
通过双光子光电发射对真空能级以下的未占据体态进行非平衡能带映射。
DOI：
--
复制
发表时间：
2010
影响因子：
8.6
通讯作者：
R. Osgood
中科院分区：
文献类型：
--
作者：
Zhaofeng Hao;J. Dadap;K. Knox;M. Yilmaz;N. Zaki;P. Johnson;R. Osgood
我们展示了角度分辨、可调谐、双光子光电发射（2PPE）来绘制大量未占据的带，即。 Cu sp 带低于真空能级 0 至 1 eV，位于 L 点附近。由于强光泵浦速率，观察到的跃迁能量及其色散与光子能量 ℏω 的关系，可以看到这种短暂的体能带，与紧束缚能带结构计算非常一致。最终态能量随 ℏω 变化的测量斜率为 ∼1.64，而从二维状态观察到的 2PPE 值为 1 或 2。这种独特的变化说明了垂直动量 ℏk_{⊥} 在 2PPE 中的重要作用。
We demonstrate angle-resolved, tunable, two-photon photoemission (2PPE) to map a bulk unoccupied band, viz. the Cu sp band 0 to 1 eV below the vacuum level, in the vicinity of the L point. This short-lived bulk band is seen due to the strong optical pump rate, and the observed transition energies and their dispersion with photon energy ℏω, are in excellent agreement with tight-binding band-structure calculations. The variation of the final-state energy with ℏω has a measured slope of ∼1.64 in contrast to values of 1 or 2 observed for 2PPE from two-dimensional states. This unique variation illustrates the significant role of the perpendicular momentum ℏk_{⊥} in 2PPE.