Wavelength selector fluorescence

Light from the broadband source is filtered by a wavelength selector and then passed into the sample container. If fluorescence occurs,... 

In summary, the basic fluorometer, and thus the basic fluorescence detector, consists of a light source and a wavelength selector (usually a filter) for creating and isolating a desired wavelength, a sample compartment, and a second wavelength selector (another filter) with a phototube detector for isolating... 

Fluorescence emission provides more selectivity and increased sensitivity compared to UV absorption. Basically, the instrumentation is composed of an excitation source, an excitation-wavelength selector, a flow cell, an emission collector, and an emission-wavelength selector. Due to their highly collimating nature, lasers are utilized as sources (He/Ne, diode, argon ion). The diode laser seems the best choice. 

Fig. 9.1 General arrangement of spectroscopic absorption/fluorescence measurement A,-wavelength selector, X-light source, D-detector, R-recorder. Intensity of initial (Io), transmitted (I), or fluorescent (Ip) light is related to the concentration of the sample C...

FIGURE 15-8 Components of a fluorometoror spectrofluorometer. Source radiation is split tnlo two beams. The sample beam passes through the excitation wavelength selector to the sample. The emitted fluorescence is isolated by the emission wavelength selector before striking the transducer. The reference beam is attenuated before striking the transducer, The electronics and computer system compute the ratio of the fluorescence intensity to the reference beam intensity, which cancels the effect of source intensity fluctuations. 

A general schematic of a fluorescent spectrometer is shown in Fig. 4.10. The instrument contains the source of UV/VIS radiation, an excitation wavelength selector, an emission wavelength selector, a sample chamber and a detector. Basically this is a single beam instrument. The fluorescence emitted by the sample is usually measured at 90° in order to avoid disturbances by non-absorbed excitation radiation. 

The first two instrumental configurations, which are used for the measurement of absorption, fluorescence, and phosphorescence, require an external source of radiant energy. For absorption, the beam from the source passes into the wavelength selector and then through the sample, although in some instruments the positions of the selector and sample are reversed. For fluorescence and phosphorescence, the source induces the sample, held in a container, to emit characteristic radiation, which is usually measured at an angle of 90° with respect to the source. 

Normally, the chiral pollutants in the environment occur at low concentrations and therefore a sensitive detection method is essential and is required in chiral CE. The most commonly used detectors in the chiral CE are UV, electrochemical, fluorescence, and mass spectrometry. Mostly, the detection of the chiral resolution of drugs and pharmaceutical in CE has been achieved by a UV mode and therefore the detection of the chiral pollutants may be achieved by the same method. The selection of the UV wavelength depends on the type of buffer, chiral selector, and the nature of the environmental pollutants. The concentration and sensitivity of UV detection are restricted insofar as the capillary diameter limits the optical path length. It has been observed that some pollutants, especially organochloro pesticides, are... 

Fig. 24 Fluorescence emission spectral plots of (R)-and (5)-TFAE enantiomers using L-AlaOMeFeCU as chiral selector. The emission spectra of TFAE were collected at an excitation wavelength of 365 nm at room temperature. Adapted from [128]...

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