Pulse generators operational circuitry

The block diagram of the electronic circuitry is presented in Fig.2 the cathodically pulsed potential (Fig.3a) for the electroluminescence generation was provided by a microprocessor-based pulse generator with a home-made potentiostat (single operational amplifier (741) with a transistor booster) photomultiplier output was amplified, demodulated by a simple gated integrator and finally registered on a recorder. 

Photodiodes are based on a pn junction operated at a reverse bias voltage (i.e., the opposite bias to the LED and diode laser). The reverse rather than forward bias voltage has the effect of increasing the voltage across the depletion region such that any photoinduced electron-hole pairs are rapidly swept across the junction, generating a current pulse in the external circuitry (Figure 12.24). 

The arc temperature profile is appreciably modified in this mode, becoming narrower with appreciably higher peak axis temperatures. More radiation from sodium lines arising from higher excited states and from the continuum results. Disadvantages of this approach are the need for special pulsing circuitry to operate the lamps and specially constructed arc tubes to withstand fracture from the acoustic shock waves generated by the pulses. 

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