Reflectance spectroscopy is the ideal technique to measure the spectral properties of opaque samples in the wavelengths of analysis that are adsorbed on surfaces, powders, or colloidal media. Instead of measuring the amount of transmitted radiation, reflectance measures the amount of radiation that is reflected by the sample. The spectrum obtained from the reflectance measurement is partly similar to that obtained from the transmittance measurement.
Reflectance for Qualitative Analysis
How to Apply the Kubelka-Munk Transformation to a Reflectance Spectrum?
Differences Between Specular and Diffuse Reflectance
Typical Setup for Reflectance Measurements
In a brief description, the light produced by a tungsten-halogen, LS-W, or a high powered deuterium tungsten-halogen light source LS-DWHP, is guided using a reflectance probe through six illumination fibers to a reflectance standard. The reflected light is collected in the center of the probe tip through a collection fiber that connects to the spectrometer and records the intensity of reflected light in real-time. Changing the standard for the sample will result in the detection of a different intensity of reflected light and, therefore, an reflectance spectra.
For UV-Vis-NIR reflectance measurements, Sarspec has two light sources available: a high-powered deuterium tungsten-halogen light source (LS-DWHP) for the UV-Vis-NIR range and a tungsten-halogen (LS-W) light source for the Vis-NIR range. Sarspec has also reflectance probes with different core diameters and lengths for illumination and collection purposes. These reflectance probes can be combined with our standard and multi-angle probe holders that yield simple and accurate measurements. Finally, the setup is completed with our FLEX spectrometer.