Unoccupied electronic states at small domains of organic films

有机薄膜的横向不均匀性常常是高分辨率光谱学的难题。我们改进了微光斑双光子光电发射光谱仪，并将其应用于有机薄膜的无占据态研究。成功地测定了酞菁铅薄膜在HOPG上的未占据水平的分散。时间分辨实验揭示了光激发形成的电子和空穴的散射过程。我们发现了象势态介导的rubrene分子的增强电子激发。

Lateral inhomogeneity of organic films is frequently troublesome for high-resolution spectroscopy. We have improved the microspot two-photon photoemission spectrometer and applied it to investigate unoccupied states of organic films. The dispersions of the unoccupied levels of lead phthalocyanine film on HOPG were successfully measured. The time-resolved experiment revealed scattering processes of electrons and holes formed by photoexcitation. We have found an enhanced electronic excitation of rubrene molecules mediated by the image potential state.