Figure 5. Resonance Raman spectrum of chlorpromazine cation radical (CPZ+) gen erated electrochemically in steady-state mode from reduced CPZ. Laser wavelength was 514.5 nm. CPZ is not resonance-enhanced and scatters too weakly to interfere with the CPZ+' spectrum. · denotes solvent peaks. (Adapted from Reference 16.)
todiode array (IPDA) positioned at the focal plane can monitor 1000 wave lengths simultaneously, in principle producing a complete spectrum in as little as 10 ns. Each channel of the IPDA is physically a 25 μπι Χ 2.5 mm rectangle and acts as a detector analo gous to the P M T used for the scanning experiment. A range of wavelengths is monitored at all times, thus lengthen ing the time monitored for each wave length and providing S/N ratio en hancement. The width of the spectrum typically monitored by our spectrome ter is 600 cm - 1 . Although the PMTs normally em ployed for Raman spectroscopy oper ate in a single-photon counting mode, an IPDA is inherently an integrating detector. Each element of the IPDA stores charge proportional to the inte gral of the number of photons striking the element. At intervals of 10 ms or more, the stored charge from all pixels is read out, and the pixel is reset. With repetitive integration and readout, it is possible to generate a series of spectra, each of which represents Raman scat tering during a 10-ms segment of time after electrogeneration begins. The se quence of events for the on-the-fly ac-
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