Multiple bondlengths and short data ranges in sexafs and exafs

Simple, but general, model calculations are presented to show that two or more similar (but slightly different) bondlength contributions of different amplitude can lead to substantial errors in an EXAFS measurement with the apparent bondlength falling outside the ranges of the actual bondlengths. The effect is most acute for short data ranges, common in Surface EXAFS, and for low symmetry adsorption sites of the type likely to occur in many molecular adsorption systems.