Historical Development of FT-Raman Spectroscopy
Preliminary Information of FT-Raman Development
Throughout the historical development of innovative instrumental techniques, the aim has always been to make improvements that would allow for a greater yield of accuracy to be achieved in a given assay, more precision within measurement, and a higher capability of detectability. With that being said, this aim towards improvement was the driving force that resulted in the development of many sophisticated analytical techniques today. However, in reference to the development of FT-Raman spectroscopy, there was an exception. This anomaly was due to the fact that the practices governing this field of study were what led to the rediscovery of this technique. Also, the fleeting rise to popularity of FT-Raman spectroscopy in analytical studies is as a result of underlying technology behind this technique .
Pioneering Experiments by Chantry et. al and Chase
The first known knowledge of an experiment being performed to analyze Raman scattered light using an excitation source in the near-infrared region coupled with an interferometer for spectral analysis was from a paper published in Nature, 1964by Chantry et al. [1-4]. In this article they go on to explain how strongly colored substances cannot be successfully examined exclusively with the use of Raman spectroscopy. This argument is based on the conception that the use of ultra-violet and visible lasers will not allow Raman spectra to be measured from these substances. However, they also noted that in the near infrared region, virtually all compounds have some degree of transparency. Therefore, they suggests that the method of circumventing this problem in examining these colored substances would be to develop a technique that comprises the use of near infrared lasers that will produce these transparent regions, which will enable Raman spectra to be measured. Their main experiment to implement this suggestion involved measuring the Raman scattering from an iodine solution dissolved in both carbon tetrachloride and a carbocyanine dye in methanol using a Michelson interferometer [3,4].In performing this experiment, they were able to demonstrate the feasibility of analyzing and obtaining Raman measurements from a solution containing such a dark pigmentation [1,3, and 4]. Granted, the results were minimal and based on the observations of broad bands, it was clear that there were still severe limitations with this technique [1, 4]. To explain, the lasers that were used in this experiment were extremely noisy. Also in using the detectors that were available to them they could only achieved poor instrumental resolution, which was not ideal [1, 3 and 4]. In addition to the instrumental limitations, the fluorescence interference caused by impurities or from the analyte itself also attributed to the poor analysis results, as well as the low number of Raman measurements acquired [4, 5]. However, this...