Equipment: Raman Spectroscopy
Raman Spectroscopy was invented in 1928 by Sir Chandrasekhara Venkata Raman and has been successfully used for many years in the qualitative and quantitative examination of liquids and gases. But only since about 2000 has sufficiently sensitive instrumentation been available to allow dyes and pigments in inks to be examined.

Raman radiation arises when a beam of light is shone onto a sample - some of the light is absorbed by the molecules in the sample and re-emitted at different wavelengths, the pattern of the emitted Raman lines being characteristic of the molecules in the sample. Hitherto it has been necessary to extract dyes and pigments from samples to examine them by Raman Spectroscopy, but new instrumentation employing a pinpoint laser beam and a highly sensitive detector now allows inks to be examined in situ, effectively permitting non-destructive testing of materials on paper.

The Giles Document Laboratory