tance values spanning from 0.001 up to 0.99 (0.1–99%). In order to
record correctly the low values, it is essential to use a spectrophotometer
with an high dynamic range, as the case of a double
monochromator system. The absorbance values A(l), and equivalently,
the PF(l) values showed a high degree of variation among
substrates. This result is consistent with several studies. Pearse and