Detectors Fluorescence Detection

a virtually black background and hence provides the maximum signal-to-noise ratio. If necessary, the background signal can be further reduced by the use of an appropriate filter to remove any stray scattered excitation light that might be received by the sensor.

The fluorescence signal (If) is given by

where $ is the quantum yields (the ratio of the number of photons emitted and the number of photons absorbed), Io is the intensity of the incident light, c is the concentration of the solute, s is the molar absorb-ence and l is the path length of the cell.

It is clear that the solute concentration is a somewhat complex function of the intensity of the emitted fluorescent light. As a consequence, the signal from the photocell must be electronically modified to produce an output that is linearly related to solute concentration.

Fluorescence detectors vary widely in complexity. The simplest consists of a single wavelength excitation source in conjunction with a sensor that responds to light at all wavelengths (UV and visible). For certain applications, this simple form of fluorescence detector can be very sensitive and inexpensive. However, by restricting the excitation light to a single wavelength, and with no means of selecting the emission wavelength, the system has limited versatility. At the other extreme is the fluorescence spectrometer that has been fitted with a sensor cell of appropriate dimensions. This comprehensive fluorescence monitoring system is highly complex and versatile and allows both the excitation and emission wave lengths to be chosen. Furthermore, excitation spectra can be obtained at any fixed emission wavelength, or an emission spectrum can be obtained for any fixed excitation wavelength.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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