Channeling ofD+andHe+Ions in Gold Crystals

The transmitted intensity of ${\mathrm{D}}^{+}$ and ${\mathrm{He}}^{+}$ ions through gold crystals in the forward direction is measured as a function of crystal orientation for energies near 15 keV. The gold crystals have a (100) orientation and are mounted in a goniometer which can tilt the foil normal up to 60° away from the incident beam direction and which can rotate the foil about its normal. The detector can be tilted relative to the beam direction up to a maximum angle of 58°. Pronounced peaks are found in the transmitted intensity at low-index directions. Both directional and planar channeling are present. The peak widths are successfully interpreted in terms of a channel-entrance peak width and a channel-exit peak width. Energy analysis shows that the energy of the transmitted ions also has peaks in the low-index directions. The experimental values for the energy loss of the randomly scattered part of the ion beam agree with the theoretical predictions.