Planar channeling trajectories in diamond and silicon

Planar channeling backscattering spectra of 230 keV protons in silicon and diamond, and of 350keV He ions in silicon have been measured. The half wavelengths and the average stopping power of ions oscillating between the crystal planes with an amplitude of half the planar spacing are determined. For the half wavelengths agreement is obtained with theoretical calculations. The average stopping power of the ions considered turns out to be roughly 50% larger than the random stopping power.