Design, characterization, and optimization of an inexpensive Raman spectroscopic system for sample identification.

摘要

The research endeavors described in this dissertation focus on the development of a low-end Raman spectroscopic system. The system was designed, characterized, and optimized with respect to instrument function and data analysis. Design criteria stipulated low cost, portability, broad application base, fiber optic sampling, commercially available components, simple data analysis, and ease of use. Primary emphasis was placed on the inexpensive aspect.; The first phase of research concentrated on instrument components. A dispersive, fiber optic Raman spectroscopic system within the aforementioned constraints has been developed. While several Raman instruments are commercially available, they meet a different set of needs. These high-end systems generally provide excellent resolution, low detection limits, and relatively short measurement times. Yet, an increase in design complexity, a decrease in ease of use, and a rise in system costs are additionally associated with these systems. The low-end Raman instrument developed in this research is foreseen as an inexpensive alternative for routine identification purposes. Attention was also placed on a number of signal and noise considerations.; After the instrumental phase of the research waned, emphasis was placed on the use of correlation analysis for sample identification. Post-consumer plastics were selected as the samples for this phase of research because they possess relative spectral simplicity while maintaining in-class variations. Additionally, they are readily available and have been successfully evaluated with other independent Raman and correlation studies. A number of spectral factors (e.g., continuum background and fixed pattern noise) were considered and their effects on correlation efficiency were evaluated. In general, a correlation approach presented promising results for sample identification.; To improve on the instrument's detection limits, surface-enhanced Raman scattering (SERS) spectroscopy was attempted with the system. A simple and inexpensive method of preparation was used for the production of SERS substrates, which involved the deposition of silver on copper circuit boards via internal electrolysis. The deposition of gold in a similar manner was evaluated as a potential SERS substrate. The results for this portion are mixed; the gold modified surface has not demonstrated consistent signal enhancement, while the silver has yielded positive results. (Abstract shortened by UMI.)