Rapid scanning Raman spectroscopy.

Rapid scanning spectrometers have been designed and built that enable Raman spectra to be obtained in a very short time. The different techniques of laser excitation and photoelectric recording are compared: conventional scanning monochromators and photomultiplier detectors achieve oscillographic recording at spectral scanning speeds up to 1000 cm−1/sec; recent progress in photoelectrical devices permits simultaneous recording of the whole spectral region, by using image intensifier phototubes placed in the focal plane of high aperture grating spectrographs. With argon ion cw lasers, the Raman spectrum is usually recorded once every millisecond. With pulsed lasers, a high resolution spectrum is recorded for every pulse whose energy is in the 2–100-mJ region. Several examples of quickly evolving chemical reactions or instable species are given.