Evolution of intsrumentation for detection of the Raman effect as driven by available technologies and by developing applications. 6

ABSTRACT : The evolution of Raman instrumentation from the time of the initial report of the phenomenon in 1928 to the present will be reviewed. The earliest systems were prism spectrographs with photographic plates, and the spectrum was excited with a mercury arc lamp. Because samples were synthesized and then extensively purified to guarantee that the spectrum was representative of the sample and not impurities, problems of Rayleigh scattering and fluorescence that became important in the period between the 1960s and 1990s were not present. During the period between the mid-1950s to the late-1970s most systems were double grating monochromators, scanned with photomulplier detectors. During the mid-1970s the first microprobes were introduced on scanning instruments, but were then adapted to spectrographs after the multichannel detectors became the method of choice for detection. Initially these were triple spectrographs where the first two stages were used in subtractive mode to filter the laser line, but after the introduction of the holographic notch filters in 1990, a new generation of truly benchtop Raman systems were developed and saw increasing popularity. 56

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