Volume 33, Issue 5 (September 1988)
Transmission and Reflectance Microspectrophotometry of Inks
Various inks were shown to obey the Beer-Lambert Law as deposits on glass slides. However, spectra of ink traces on paper are subject to scattering and bronzing interferences which cause deviations from the law. Theoretical considerations and experimental results show that there is an inherent advantage of the transmission method over the reflectance method since the former does not suffer from bronzing interference. The deviations from the law may be considerably lower using transmission microspectrophotometry of single inked fibers in a mounting medium instead of the nondestructive transmission method because of large variations in the opacity of paper substrates. In any case, when measuring spectra of ink traces on paper, care must be taken when applying the Beer-Lambert Law to normalize spectra to eliminate concentration differences and substrate background contributions.