PowderPro™

Additional Information

This single reflection ATR accessory is a powerful analytical tool for repeatable qualitative and quantitative studies of organic and inorganic powders. The PowderPro™ builds on our high performance FastIR design to make a convenient powder sampler. For versatility, the PowderPro™ can be adapted for use with solid, liquid, and pastes.

The simple efficient optical design of this ATR accessory combines high optical throughput with the convenience of horizontal sampling. Installation and alignment are simple. The high energy throughput allows excellent spectra to be obtained even with weakly absorbing samples. Sample preparation is minimal compared to conventional diffuse reflectance accessories where the sample must be diluted to avoid spectral distortions. This greatly simplifies both qualitative and quantitative work.





Figure 1. Optical drawing of the PowderPro™.


An optical drawing of the PowderPro™ is shown in Figure 1. Light from the FT-IR spectrometer source strikes mirror M1. The reflected light then strikes the 45° single reflection crystal at normal incidence and passes through the ATR crystal until it is internally reflected at the sampling surface. The light interacts with the sample and exits the other 45° face at normal incidence. The radiation then reflects from mirror M2 to the detector of the spectrometer. This design provides a high degree of insensitivity to precise alignment. The optical assembly of the PowderPro™ rotates so the crystal can be exposed for cleaning and easy removal.

The standard ATR crystal is made of ZnSe. This has a wide useful spectral range (20,000 cm^-1 to 500 cm^-1) and durable mechanical properties. Alternative materials are also available. The crystal is held in place with a gasket. This gasket does not interact with the sampling radiation. Thus spectra are free from any spurious peaks or energy degradation due to the interaction of the light with the adhesive.

Powders and solids may be analyzed by simply placing the sample in the sampling cup or on the sampling tray, sliding the sample into the accessory along its rails, and then compressing the sample with the built-in pressure applicator. For repeatable measurements, use of a torque screwdriver to maintain reproducible contact pressures is recommended.

Two types of sample holders are available for the PowderPro™. The Sample Cup is designed to retain virtually any amount of powder to be pressed against the crystal. The Sample Cup can easily be fully disassembly for cleaning.

The PowderPro™ can be inverted for horizontal sampling of pastes, solids and liquids. For solids, the PowderPro™ pressure applicator can be readily replaced with a standard press. For liquids, a trough and a flow-through configuration are available.

Figures 2 through 4 show spectra of various powders recorded using the PowderPro™.



Figure 2. ATR spectrum of talcum (dotted) and cornstarch (solid) baby powders.



Figure 3. ATR spectrum of silica-based powder with a 5 mm grain size.



Figure 4. ATR spectrum of rye flour.