Probes offer a convenient alternative to measuring fluorescence in a cuvette. When immersed in a solution, they excite and detect fluorescence of the sample material closest to the tip. This enables measurements of flowing solutions, as well as samples that are highly concentrated or prone to reabsorption of emitted fluorescence. Probes are also excellent for direct measurement of solid and particulate samples.
Fluorescence in Solutions
A basic reflection or backscatter probe works very well for making fluorescence measurements in solution. A probe with a large core fiber such as the QR600-7-UV-VIS will excite and collect the most fluorescence.
For process applications, a more robust probe such as our front-surface fluorescence probe may be warranted. It requires very little penetration into the sample and is compatible with industrial fittings.
Fluorescence of Solids and Powders
Solid and powdered samples don’t lend themselves well to traditional cuvette-based spectrofluorometer measurements. A reflection probe, however, can perform excitation and detection of fluorescence when angled and placed in a probe holder at a small, repeatable distance from the sample. This allows samples to be measured in place and non-destructively.
Application tip: To see the most spectrally accurate fluorescence spectrum, first perform a relative irradiance calibration of the spectrometer. This will ensure that the varying response of the spectrometer with wavelength has been corrected, giving the proper fluorescence spectrum shape.