Abstract
For momentum transfers of order 6 A nondipole transitions can make the same contribution to inner-shell energy-loss spectra as dipole transitions. Nondipole transitions are particularly significant when there is a high density of dipole-forbidden states in the near-threshold region. We have studied the near-threshold region in the excitation of molybdenum 3d and the excitations of 2p electrons in and SiC as a function of scattering wave vector q. At large q dipole-forbidden monopole transitions become visible as a sharp peak on the ,5 threshold for molybdenum corresponding to 3d→4d transitions or as a change in the ,3 peaks intensity ratio in the cases of titanium and silicon. Experimental results are confirmed by calculations.
- Received 5 January 1989
DOI:https://doi.org/10.1103/PhysRevB.40.2024
©1989 American Physical Society