General Outline and Strategies for IR and Raman Spectral Interpretation

There are common tools and skills used for solving structural problems using vibrational spectroscopy, which include interpersonal and communication skills, defining the problem and getting background information on the sample, instrumentation, selecting the most appropriate technique and sample preparation, data analysis techniques, spectral interpretation skills, experience in selecting the most appropriate tool for application, spectral database, and ab initio-based normal mode analysis. Basic instrumental techniques for bulk analysis include mid-IR as well as Raman spectroscopy. When examining smaller samples microanalysis techniques must be employed such as microscopy. Chemometric data analysis may be employed for developing quantitative models or analysis of large spectral data sets. Five different general criteria for IR sample preparation are: suitable band intensities in the spectrum, baseline, atmospheric compensation, spurious bands, and X-axis scale. Both the sample IR and Raman spectrum and any reference spectrum must be of good quality. Resources to use include electronic and paper libraries, empirical characteristic frequencies for chemical functional groups, as well as outside vendor and interior libraries. The quality of the available reference library is critical. The first step of interpreting the IR and Raman spectrum is to identify any common impurities that could be present.