ABSTRACT
By measuring the very low energy photoemission spectra of the CO/Cu(001) surface with a high resolution, we have found the energy loss components due to inelastic scattering of electrons near the Fermi level by the CO vibrational modes. The main energy loss structure appears as a step at 254 meV below the Fermi edge for 12C16O. An isotope shift of the step to 240 meV was observed when 13C18O was adsorbed. This observation confirms that this step arises from the energy loss of photoelectrons near the Fermi level through the excitation of the C-O stretching mode.
ABSTRACT
By measuring the photoelectron spectra of the Cu(001) and Cu(110) surfaces excited by tunable-laser photons of very low energy (4.50-4.95 eV), we have found that the photoelectron can lose energy through interaction with its image charge. This energy loss occurs just outside the solid surface and appears as a spike structure at the vacuum edge in the photoemission spectra. The requirement for observing this energy loss structure is the absence of unoccupied states at the vacuum level at the Gamma point to which zero kinetic energy electrons can return.
ABSTRACT
By injecting low-energy minority carriers from the tip of a scanning tunneling microscope (STM) and analyzing the light emitted from the tip-sample gap of the STM, it is possible to study the optical and electronic properties of individual semiconductor nanostructures with an extremely high spatial resolution close to the atomic scale. This technique has been applied to investigate the transport properties of hot electrons injected into AlGaAs/GaAs quantum well structures and the optical properties of single self-assembled InAs/AlGaAs quantum dots. The physical principles, usefulness and future expectations of this novel technique are discussed.
