We use an integral equation approach to finding the Kubelka-Munk (KM) diffuse reflectance formula and extend the result by finding the apparent path length and total intensity distribution inside an infinite, homogeneous, diffusely reflecting medium with isotropic scattering. We then expand the approach to three dimensions to show that the KM formula is correct for total diffuse reflectance when scattering, excitation, and detection are all isotropic. We obtain simple and exact results for the angular distribution of diffuse reflection and for the total diffuse reflectance when the incident light has an isotropic angular distribution, when it strikes at a single angle of elevation, and when it has the steady-state angular distribution. This work includes some results that employ Chandrasekhar's H function, so we also provide a program for the rapid evaluation of H. “[Supplementary material is available for this article. Go to the publisher's online edition of Applied Spectroscopy Reviews for the following free supplemental resource: Program to compute the value of Chandrasekhar's H function]

A quantitative comparison of Raman and Fourier transform near-infrared (FT-NIR) spectroscopic techniques for the analysis of epoxy curing is performed. It is shown that the Raman technique yields a linear calibration curve much like FT-NIR. Band assignments in the Raman spectrum of diglycidyl ether of bisphenol-A (DGEBA) were performed by studying Raman spectra of smaller model compounds.

A Novel fiber-optic configuration with forward-scattering light collection is used to measure Raman spectra using long optical fibers with little background interference. This probe design allows control over the sample volume, and measurements can be made at considerable distances from the face of the optrode. The properties of this optical configuration are discussed, as well as its advantages and disadvantages. Normal Raman spectra were measured with this technique, with fibers as long as 100 m. The performance of the probe is not affected by highly scattering solutions. A similar technique was used to measure surface-enhanced Raman spectra on Ag electrodes with 250-m fibers.