Fluorescence spectroscopy, also known as fluorometry or spectrofluorometry, is a type of electromagnetic spectroscopy, which analyses fluorescence from a sample.

 

It involves using a beam of light tp excite the electrons in molecules of certain compounds and causes them to emit light which is typically, but not necessarily, visible light. It is a useful technique in many biological (chlorophyll and carotenoid), biochemical (fluorescence diagnosis of malignancies) and environmental applications.

 

For most fluorescence applications, the amount of fluorescence energy emitted is only around 3% of the amount of excitation light energy. Fluorescence light also has a lower energy (higher wavelength) than the excitation energy and is usually scattered light - this means it emits energy in all directions.

For optimal performance, assuming the time acquisition window is not limited, we recommend our AvaSpec-ULS2048LTEC spectrometer for this application. It can support long integration times often exceeding 5 seconds. When higher-speed acquisition is required, we recommend the AvaSpec-ULS2048XL back-thinned CCD spectrometer. For maximum sensitivity, the SensLine range spectrometerer AvaSpec-HS1024x122-USB2 is recommended.

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When configuring the measurement setup, preventing excitation light from entering the spectrometer is an crucial issue. Possible methods to accomplish this, where one does not exclude the other, include:

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• Make use of an AvaLight-LED light source which typically has a narrow bandwidth enabling the limitation of excitation to shorter wavelengths that are not part of the emission spectrum

• Use a broadband light source such as the AvaLight-HAL-Mini for high output in combination with an (interference) bandpass or lowpass filter.

• Make sure the optical path for excitation light and fluorescence are perpendicular - this means the excitation light will not enter the receiving fibre (use the CUV-UV/VIS-FL or the CUV-DA)

• Use the fluorescence decay time to separate excitation energy from the integration time start pulse. A pulsed light source can be used for this (pulsed laser or AvaLight-XE Xenon flash)