COMPARISON BETWEEN ELECTRONS AND X-RAYS FOR STRUCTURE DETERMINATION.

Previous comparisons between electrons and X-rays for monitoring the fine structure past atomic core edges neglected some features to the detriment of electron monitoring. The fine structure contains information on the arrangement of atoms in the vicinity of the absorbing atom. In the comparison here account is taken of the actual method of monitoring the X-ray absorption by secondary electron emission and the fact that high energy electrons can display the whole loss spectrum simultaneously. By designing instrumentation to take full advantage of the information in the scattered electron beam, it is shown that edges below about 3000 ev can be measured by electrons with similar statistical accuracy to what is possible at synchrotron radiation sources. The radiation damage from high energy electrons may even be less than that from X-rays for a given statistical accuracy, depending on the mechanism of radiation damage.