Teledyne 6650 - Fluorescence Probe - Oil in Water analysis system - Manual (Page 9)

UV-Photo-X Introduction
Teledyne Analytical Instruments 1
Introduction
1.1 Theory of Operation
The ability to monitor the concentration of an analyte in a process
stream is critical for accurate and reliable process control. There are
many techniques used to determine the analyte concentration of interest.
One of the most sensitive sensing techniques is molecular fluorescence.
Fluorescence occurs when a molecule absorbs light energy, either
ultraviolet or visible, and rapidly emits light, at some longer wavelength.
Fluorescence of this type is referred to as Stokes fluorescence.
Fluorimetry characterizes the excitation and emission properties of the
molecular species. Figure 1-1 shows an example of the excitation and
emission spectrum from a hypothetical fluorophore.
Fluorimetry is concerned with two types of information: 1) The
(spectral) wavelength distribution, which is characteristic of the
electronic properties of the molecule, and 2) The intensity of the
fluorescence, which is typically correlated to the concentration of the
fluorescent molecule in the solution.
Figure 1-1: Molecular Fluorescence Example