Chopped emission light

Systems Using Flash Lamps and Chopped Emission Light... 

The basic instrumentation for atomic-fluorescence spectroscopy is shown in Figure 10.13. The source is placed at right angles to the monochromator so that its radiation (except for scattered radiation) does not enter the monochromator. The source is chopped to produce an AC signal and minimize flame-emission interference. As in molecular fluorescence (Chap. 9), the intensity of atomic fluorescence is directly proportional to the intensity of the light impinging on the sample from the source. 

For TRFM of lanthanides light sources providing UV or near UV have been applied, either in pulsed form (xenon flash lamps) or as continuous radiation [xenon and mercury lamps, argon lasers, or light emitting diodes (LEDs)] in combination with light chopping modules. Importantly, for maximum emission the excitation... 

Marriott et al. [15] constructed a phosphorescence microscope, in which a laser or an arc lamp was used. The excitation light was focused onto a rotating excitation chopper blade so that the on-off transit time of the excitation pulse was kept at a minimum. A quartz optic fiber was used to lead the light into the microscope. The emission chopper and slit assembly were placed as close as possible to the CCD camera. The two choppers were rotated at the same speed and phase locked. Note that in all setups a small aperture plane of excitation light is created for fast and effective chopping (Fig. 3). 

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