We present an overview of the experimental method and physical principles o
f scanning tunneling microscope (STM) light emission spectroscopy (STM-LES)
. By this new spectroscopic technique one can obtain the optical emission s
pectra of specific and individual surface nanostructures that are imaged by
the STM. This method has been used to investigate the electronic transitio
ns in surface nanostructures such as the protrusions of porous Si, the quan
tum wells of a semiconductor, and the rows and valleys of the reconstructed
Au(110) surface. (C) 2000 Elsevier Science B.V. All rights reserved.