摘要
The tunneling current of a scanning tunneling microscope is reported to cause light emission from the metallic quantum well system Na on Cu(111). Optical spectra along with tunneling spectroscopy show that one component of the emission is due to interband transitions between quantum well states of the Na layer. The other component is similar to plasmon-mediated emission observed previously from noble metals. The emission is a unique local probe of the electronic structure of this quantum well system. © 2001 The American Physical Society.