F. Rebentrost, 2ND-HARMONIC GENERATION AND EFFECT OF ADSORBATES FOR FREE-ELECTRON METAL AND SEMICONDUCTOR SURFACES, Progress in Surface Science, 48(1-4), 1995, pp. 71-81
We discuss aspects of a developing microscopic theory of SHG from simp
le metal and semiconductor surfaces. For semiconductors calculations o
f the dynamical nonlinear susceptibility on the basis of realistic tig
ht-binding parametrizations of the electronic Hamiltonian provide a pr
actical scheme, In the resulting spectra the effect of the dangling bo
nds on SHG is clearly seen together with a strong decrease upon satura
tion with H atoms, In the metal case the adsorbate induced changes of
the static nonlinear electron density can be calculated self-consisten
tly by applying density functional theory to the jellium model, The se
cond-order dipole moment determines the effect of adsorbates on the SH
G intensity in the adiabatic limit, Quite general a correlation with t
he nature of the adsorbate expressed by its electronegativity and the
characteristic charge transfer, adsorption dipole and polarizabilities
in first and second order is found.