Diffuse Reflectance Infrared Spectroscopy: Sampling Techniques for Qualitative/Quantitative Analysis of Solids
This chapter discusses some of the sample techniques that can be utilized to obtain high quality infrared spectra using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). Quantitative results of a powdered sample can be obtained if the proper sample preparations are made. These powdered sample preparation techniques are discussed. The chapter introduces a new sampling method which utilizes silicon carbide abrasive paper to collect spectra of nonpowdered samples which greatly increases the usefulness of the DRIFTS technique. It also discusses the variables which effect the reproducibility of collecting spectra. Examples are provided to demonstrate the qualitative and quantitative nature of the technique. An example of the quantitative nature of the DRIFTS technique is to determine the degree of polymerization of a composite resin matrix after curing. For quantitative analysis, the internal scattering of radiation must be held constant. This can be accomplished by carefully screening samples, establishing an Internal Reference Material for the system, and keeping a control chart.