Measuring scattering solutions
Solutions with suspended particles, even particles too small to see with the naked eye, will scatter light at all wavelengths in addition to any electronic absorbance associated with the species in solution that you want to analyze. This scattering attenuates the beam, so the measured transmittance is lower (absorbance is higher) than the “true” value for the analyte. In a conventional cuvette experiment most of the light that scatters away from the axis of the beam does not reach the detector. With an integrating sphere directly behind the sample nearly all of the forward scattered light enters the sphere where the photons bounce around until they strike the detector and are measured as transmitted light. With the ISA-220 integrating sphere, your measurements of scattering solutions become more accurate, more reproducible, and far less dependent on the distribution of particle sizes in solution than they would be in a simple cuvette experiment.
Measuring scattering solids
How much light of a particular wavelength passes through your container wall? How effective is your UV-absorbing coating or additive? If you measure a scattering solid without an integrating sphere, you only measure the photons that pass through the material and stay on-axis. The result is that you get an artificially low reading of the total transmittance. For highly scattering container walls, the error can be as large as 1000x! Choose the ISA-220 to measure how much light really passes through your material.
If your material is a monolithic solid the only way to measure its electronic absorption properties is to reflect photons off it. In such a case, an integrating sphere is the only option. Light reflected at all angles is captured and measured by the sphere. Thermo Scientific™ INSIGHT™ software for the Thermo Scientific™ Evolution™ 220 can measure directly in Kubelka-Munk units to help simplify your studies of electronic structure. If you need to measure the color of an object you can do this too. Simply scan it across the appropriate range for the color scale of your choice and use our Thermo Scientific™VISIONlite™ ColorCalc software to calculate the color parameters you need.
Choose the ISA-220 powder cell holder and you need only 0.5 cc of material to make your measurement. The powder cell holder comes with a reference cell filled with a Spectralon plug and a sample cell where a spring and piston design carefully compresses your finely ground sample for accurate measurement.