  We consider the process of cold emission of electrons from a metal in a
strong low-frequency laser field. An expression is obtained for the electron
spectrum with allowance for their rescattering at the metal surface as a result
of an extension of the Fowler-Nordheim theory and modification of the Simplemen
model. The numerically simulated features of the electron spectrum are similar
to the ATI spectra for atoms and have the same form as the experimental surface
emission dependencies for a metal.
