ANALYTICAL APPLICATIONS OF FOURIER TRANSFORM INFRARED SPECTROSCOPY (PHOTOACOUSTIC, PAS, TIME-RESOLVED, TRS)

Time resolved spectroscopy (TRS) is presented as a technique for obtaining the infrared spectrum of reversible systems undergoing physical and/or chemical changes. The technique is demonstrated for two polymer systems: isotactic polypropylene and polybutyleneterephthalate. Both systems are examined by TRS while undergoing physical deformation. An electronic triggering system is described whereby TR spectra may be obtained with a time resolution of approximately one msec. The experiments performed show that the acquired data are not restricted to any one sampling period.;The applicability of photoacoustic spectroscopy (PAS) to condensed-phase samples is reviewed. The technique is shown to be highly useful for the infrared characterization of intractable samples. Time consuming sample preparation techniques required for other infrared sampling methods are not required for PAS. The ability to perform quantitative infrared spectroscopy is also discussed. The feasibility of performing depth profiling by PAS is studied and the effects of phase errors are examined.;Similar results obtained with static stretch studies indicate that the TR technique is feasible for characterization of dynamic infrared changes on the msec time scale. The effect of sample prestretch and dynamic stretch on the infrared spectrum and how these factors are related to the changes observed are also discussed.