Paw. Vanderheide et al., THE INFINITE VELOCITY METHOD - A NEW METHOD FOR SIMS QUANTIFICATION, Surface and interface analysis, 21(11), 1994, pp. 747-757
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.