FTIR image analysis

When a focal plane array (FPA) with a moderate size of 64 x 64 elements is used, the resulting spectral cube consists of 4096 spectra. This massive amount of data is 

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Each of these sampling analysis methods has advantages and disadvantages for FTIR imaging of polymeric systems as elucidated next. 

Fourier-Transform Infrared (FTIR) spectroscopy as well as Raman spectroscopy are well established as methods for structural analysis of compounds in solution or when adsorbed to surfaces or in any other state. Analysis of the spectra provides information of qualitative as well as of quantitative nature. Very recent developments, FTIR imaging spectroscopy as well as Raman mapping spectroscopy, provide important information leading to the development of novel materials. If applied under optical near-field conditions, these new technologies combine lateral resolution down to the size of nanoparticles with the high chemical selectivity of a FTIR or Raman spectrum. These techniques now help us obtain information on molecular order and molecular orientation and conformation [1],... 

Fig. 2 Generation of spectroscopic FTIR images, a Native sample, here a thin section of biological tissue, b FTIR spectra are collected at every pixel of the native sample. Bad spectra, e.g. from areas outside the sample, have already been removed, c Good spectra have been subject to a chemometric cluster analysis. Pixels are color-coded according to the cluster membership (spectral staining). Slightest chemical differences across the sample are now clearly revealed...

Shelton, CT, www.perkinehner.com). Samples can be measured in reflectance mode or transmission mode. Sohd samples such as biological tissues may need to be sliced into thin sections for transmission analysis. FTIR imaging can be performed on a wide variety of sample matrices, including polymers, pharmaceutical tablets, fibers, and coatings. 

Fast FTIR imaging showed that the diffusion of liquid crystal 4-n-pentyl-4 -cyanobiphenyl into a poly(butyl methacrylate) matrix exhibited anomalous diffusion behaviour. A fit to several models was attempted, but no single model described the observed diffusion behaviour adequately. A simple mass uptake analysis would have indicated that diffusion occurred according to Fick s second law, whereas fast FTIR correctly identified the process as anomalous. 20 refs. 

Other uses of an IR microscope in forensic analysis include the examination of fibers, drugs, and traces of explosives. For example, oxidation of hair can occur chemically or by sunlight oxidation of cystine to cysteic acid can be seen in hair fibers by FTIR microscopy (Robotham and Izzia). Excellent examples in full color of FTIR imaging microscopy can be found on the websites of companies like PerkinElmer and Thermo Fisher Scientific. Our limitations in use of gray scale make many of the examples unsuited for reproduction in the text. A novel IR microscope combined with atomic force microscopy, the nanoIR platform from Anasys Instruments (www.anasysinstruments.com), permits nanoscale IR spectroscopy, AFM topography, nanoscale thermal analysis, and mechanical testing. 

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