SPECTROSCOPIC STUDIES OF LITHIUM IN AN ULTRAHIGH-VACUUM SYSTEM

The surface films formed on lithium in dimethoxyethane (DME) and LiAsF 6 solution in DME were investigated using X-ray photoelectron spectros copy (XPS) and Auger electron spectroscopy (AES) in an ultrahigh vacuu m (UHV) system. Fresh Li surfaces in DME were prepared under UHV condi tions by Argon sputtering of bulk lithium followed by immersion in the solution phase (under Argon), and characterization by the above spect roscopies, all within the UHV transfer system. It was found that the s urface layers formed on Li in DME contain Li methoxide and LiOH or Li2 O species (attributed to water reduction). When LiAsF6 was present, th e surface films also contained LiF. Depth profiling by Argon sputterin g and AES measurements seem to be consistent with a bilayer structure of the surface films in which the oxide-hydroxide layer is abuts the L i surface and solvent reduction species comprise the outer part of the film.