[‚kar·ik·tə′ris·tik ′lȯs ‚spek′träs·kə·pē] (spectroscopy) A branch of electron spectroscopy in which a solid surface is bombarded with monochromatic electrons, and backscattered particles which have lost an amount of energy equal to the core-level binding energy are detected. Abbreviated CLS.AcronymsSeeCLS