Scanning tunneling microscopy investigations of unoccupied surface states in two-dimensional semiconducting β-√3 × √3-Bi/Si(111) surface.

Two-dimensional surface structures often host a surface state in the bulk gap, which plays a crucial role in the surface electron transport. The diversity of in-gap surface states extends the category of two-dimensional systems and gives us more choices in material applications. In this article, we investigated the surface states of β-√3 × √3-Bi/Si(111) surface by scanning tunneling microscopy.

Insight into vibration mode-resolved plasmon enhanced Raman optical activity.

Vibration mode-resolved plasmon enhanced Raman optical activities (PE-ROA) are investigated experimentally and theoretically. It is found that the profile of PE-ROA is significantly different from that of ROA. Our experimental results revealed that PE-ROA is not a universal method for the enhancement of ROA.