THE INFINITE VELOCITY METHOD - A NEW METHOD FOR SIMS QUANTIFICATION

Twelve elements spanning a mass range of 197 atomic mass units from fi ve standard reference materials and three implant materials were analy sed to ascertain the validity of a new method, termed the infinite vel ocity method, for quantifying the negative monatomic secondary ion emi ssions resulting from Cs-bombarded surfaces. This method extracts quan titative data by extrapolating secondary ion yield versus kinetic ener gy data to the infinite velocity limit. Extrapolation to infinite velo city is done because matrix effects are theoretically predicted to be removed at this limit. Plotting the extrapolated data against known co ncentrations for the homogeneous standard reference materials yielded Linear standardization curves for all elements analysed, indicating th at the matrix effect is indeed removed, i.e. sensitivity factors were not required. Likewise, the resulting concentration profiles of the im plant materials analysed agreed well with concentration profiles calcu lated via the integration method. Thus, samples can be quantified by t his procedure without the requirement for matrix-matched calibration m aterials. Theoretical implications and the assumptions used in the cal culations are also discussed.