A combined remote Raman and fluorescence spectrometer system for detecting inorganic and biological materials

摘要

We have developed a combined remote telescopic Raman and laser-induced native fluorescence (LINF) spectrograph with 532 nm pulsed laser excitation and a gated CCD detector. With this system, we have measured time-resolved Raman and LINF spectral measurements at 9 m with 10-ns time resolution. A comparison of Raman spectra of calcite crystal and that of chicken eggshell show that the CaCO_3 in the chicken eggshell is arranged in a calcite structure. The strong LINF band in the spectrum of the calcite crystal has lifetime longer than 1 μs, whereas the lifetime of LINF bands of the eggshell are in 10's of nano-sec (ns). The time-resolved Raman spectra of tomato and poinsettia (Euphorbia pulcherrimum) green leaves show resonance Raman features of carotenes. The time-resolved remote LINF spectrum of ruby crystals, and LINF spectra of tomato and poinsettia green leaves yield information that the LINF lifetime of ruby lines is much longer (in milliseconds (ms)) as compared with the fluorescence lifetime of the tomato and the poinsettia leaves (in 10s of ns). These results show that it will be possible to discriminate between inorganic and biogenic materials on the basis of LINF lifetimes even with 8 nano-sec laser pulses and gated detection.