Energy Dependence of Diffraction Intensities: ⁴He + LiF (001)

The dependence of specular and first order diffraction probabilities on the atom beam energy has been calculated for the system He + LiF (001) in the energy range 18 to 58 meV. A realistic Lennard‐Jones—Devonshire atom surface potential with several values of the β‐parameter, determining the strength of the corrugated part, was used. A comparison with the predictions of the simple Rayleigh—Eikonal approximation shows agreement with respect to the overall trends, however the quantal calculations show some deviations and the additional effect of selective adsorption resonances. The results are compared with recent measurements for the (100) and (110) directions and good agreement is found for β 10 = 0.086.