An extension of the nonlinear least squares spectrum fitting technique
has been developed for the simultaneous fitting of multiple spectra.
This procedure's smaller number of fitted parameters as compared to fi
tting one spectrum at a time improves the determination of spectroscop
ic parameters. A more reliable evaluation of the errors associated wit
h the solution is possible. Correlations among fitted parameters may p
reclude their determination from a single spectrum fit. If the correla
tions differ from spectrum to spectrum, however, separation of these p
arameters is often possible when including the spectra in one solution
. Overfitting is also avoided when combining spectra with sufficiently
different experimental physical conditions.