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These techniques can be combined with microscopy, to map the intensity (confocal microscopy) or the lifetime (fluorescence-lifetime imaging microscopy) of the photoluminescence across a sample (e.g. a semiconducting wafer, or a biological sample that has been marked with fluorescent molecules). Modulated photoluminescence is a specific method ...
Fluorescence of aragonite Necklace of rough diamonds under UV light (top) and normal light (bottom) In addition to the eponymous fluorspar, [66] many gemstones and minerals may have a distinctive fluorescence or may fluoresce differently under short-wave ultraviolet, long-wave ultraviolet, visible light, or X-rays.
This results in a better signal-to-noise ratio, and lowers the detection limit by approximately a factor 10000, [3] when compared to the 180° geometry. Furthermore, the fluorescence can also be measured from the front, which is often done for turbid or opaque samples . [4] The detector can either be single-channeled or multichanneled.
The fluorescence is (a.) demodulated and (b.) phase shifted; both quantities are related to the characteristic decay times of the fluorophore. Also, y-components to the excitation and fluorescence sine waves will be modulated, and lifetime can be determined from the modulation ratio of these y-components.
The quest for fluorescent probes with a high specificity that also allow live imaging of plant cells is ongoing. [7] There are many fluorescent molecules called fluorophores or fluorochromes such as fluorescein, Alexa Fluors, or DyLight 488, which can be chemically linked to a different molecule which binds the target of interest within the sample.
Piezospectroscopy can be used on any material that exhibits fluorescence, but is almost exclusively used on samples containing alumina because of the presence of chromium ions, either as part of the composition or as an impurity, that greatly increase the fluorescent response.
Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluorescence, a phosphorescent material does not immediately reemit the radiation it absorbs.
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction, i.e. a chemical reaction results in a flash or glow of light. A standard example of chemiluminescence in the laboratory setting is the luminol test. Here, blood is indicated by luminescence upon contact with iron in hemoglobin.