Axiom Analytical's RFP-460 Multipass Raman Probe probe provides up to an order of magnitude enhancement in the sensitivity of Raman spectroscopy when used for the analysis of gases and clear liquids
The principles underlying the operation of the RFP-460 Multipass Raman Probe were described recently in a paper given by Michael Doyle at the International Forum on Process Analytical Chemistry (Ifpac), held in Baltimore, 27-30 January 2008.
The paper reported the achievement of marked sensitivity enhancement, with no undesirable side effects, through the use of a design previously developed by Doyle (US Patent 6,795,177 B2).
The significantly improved performance was made possible by combining the multipass approach with recent advances in interference filter technology.
Raman spectroscopy is a powerful technique for chemical analysis which combines the specificity of mid-infrared spectroscopy with the convenience and flexibility of near-infrared.
It is based on the use of a focused laser beam to cause a condensed substance to emit a spectrum of optical radiation that is uniquely related to its molecular structure.
Doyle's advance takes advantage of the fact that Raman scattering is an extremely week phenomenon and is only made practical by the high energy density of the focused laser beam.
Very little attenuation of the laser signal takes place.
In principle, it is thus possible to pass the same laser beam through a sample more than once.
Doyle's approach makes it possible to accomplish this by means of a straight forward modification to Axiom's standard Raman probes -- making multi-pass Raman practical, economical, and highly effective.
