Date of Award
Doctor of Philosophy (PhD)
John B. Cooper
Linda L. Vahala
Vishnu K. Lakdawala
Raman spectroscopy is a powerful technique for molecular structural studies and concentration measurement. Being a single beam technique, the Raman intensity depends on the optical power of the excitation source, optical alignment of the system, detector response as well as species concentration. To eliminate the unwanted variations in the system and get the concentration information of the species, intensity referencing is necessary. The existing referencing methods either use a constant Raman band of the sample, or add a chemically inert material with known concentration into the sample. Unfortunately, the former method is not always applicable and the latter is not acceptable for in situ process monitoring. A new concept of using diamond as an intensity standard in quantitative Raman analysis is presented in this dissertation. Combined with fiber optics, a self-referenced universal Raman probe is developed. Performances of five probe designs are investigated. Results indicate that diamond-referenced probes are insensitive to the excitation power fluctuation and optical alignment. Chemical vapor deposited (CVD) diamond film is investigated as an alternative to the expensive bulk diamond. The CVD diamond referenced probe shows performance similar to the bulk diamond probe. A remote measurement is also performed with a 500-foot fiber probe, which shows the potential of long distance in situ concentration monitoring in an industrial environment.
"Diamond for Fiber-Optic Raman Spectroscopy"
(1997). Doctor of Philosophy (PhD), dissertation, Electrical/Computer Engineering, Old Dominion University, DOI: 10.25777/3mpc-wq26