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Questions tagged [fluorescence]

For questions relating to the radiation emitted by substances as a result of incident radiation.

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Choosing the right wavelength for calibration curve and for analysis of actual results

Introduction: I am currently conducting a series of experiments in which I am studying the transport of polystyrene nanoparticles (PNPs) through sand and soil. This is done in sand/soil columns, into ...
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What's causing this dip in the FCS curve?

This is a fluorescence correlation spectroscopy measurement of light harvesting complexes. What could be causing the dip at 100 microseconds? Edit: The same thing was observed using fluorescence ...
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What fluorescent materials absorb visible light and emit UVC light?

What fluorescent materials, if any, exhibit anti-stokes shift such that they absorb visible light and emit ultraviolet light in the range of 250-285 nm? I'm interested in particular in materials that ...
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Is Beer-Lambert law also valid for fluorescence and luminescence?

When I measure optical density in a microplate reader the absorbance is proportional to the concentration and the height of the liquid. Is Beer-Lambert law also valid for fluorescence and luminescence?...
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What is the relationship between emission and fluorescence?

A molecule exposed to a photon with some energy is put into an excited state, and emits a photon of some energy when it returns to ground state. The photon that provided the energy for excitation ...
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Self tan mousse cannot contain UV, right?

So, I bought this self tanner specificly to avoid UV radiation. Back home I noticed that the bottle says it contains ultra violet: "The inclusion of Ultra Violet fluorescence in the base colour" . I ...
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Two-part fluorescence behaviour of DNA oligo tagged with Cy5 fluorophore. Explanations?

We have designed a 56nt single-stranded DNA oligo. Its sequence has no predicted secondary structure, and no predicted reaction with other similar oligos. A Cy5 fluorophore is attached at the 5 prime ...
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How does light emission depend on temperature by fluorescence?

I have a glass, which emits green light after charging it with sunlight. I though this is fluorescence, and only photons with shorter wave length (than the green light has) can excite the electrons of ...
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How does pH affect fluorescence quantum yield?

I have read in a scientific paper that: the light intensity produced by the decomposition 3–aminophthalate in the oxidation of luminol (involving hydrogen peroxide and iron (II) sulfate heptahydrate) ...
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Why does aqeous fluorescein shine when exposed to UV light?

I know that (aq) fluorescein "absorbs" UV light and releases light in the visible spectrum , but how does it do that. It is a really interesting and useful organic chemical and I just wanted to know ...
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Why don’t fluorescent compounds glow in the Sun?

Fluorescent compounds exhibit a glow because of their exposure to UV. Since sunlight is 10% of UV, why don’t fluorescent compounds simply glow in the Sun? Is it because the UV there is just not enough?...
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Are there any (simple) molecules with very different absorption and emission dipole directions?

When a single molecule absorbs or emits light, it does so perpendicular to the direction of the respective transition dipole. In principle, the directions of the dipoles for absorption and emission ...
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Is it right to say that fluorescent lamps are actually fluorescent?

Fluorescence occurs rapidly ($\approx 10^{-6}$ to $10^{-9}$ s) but phosphorescence is slow, and is therefore observable ($> 10^{-4}$ s). So, is it right to say that fluorescent lamps actually ...
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What is the exact relationship between the Pi conjugated bonds in organic molecules and fluoroscence of those molecules?

Some compounds are more fluorescent than others, and some of those are Rhodamine, Phenolphtalin, naphthalene, anthracene etc. I want to know why these exact molecules undergo such phenomena, what is ...
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Calcium detection using XRF

I have a mixture of metal oxides in powder form. Mainly Iron oxide, silicon dioxide, and calcium oxide. I know for certain calcium oxide is in the mixture, but my handheld XRF is not detecting it. I ...
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Does the laser side of laser fluorescence spectroscopy have to be so complicated?

I understand the working principle behind zapping some gas and looking at spectral emissions, and I can see why photodetection is so difficult. But I thought that pointing a laser into a vacuum ...
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What makes scorpions glow under UV light?

What substance (or class of substances) is responsible for the neon blue-colored fluorescence we observe when we shine UV light on scorpions? Do note, I want to know what substance makes them glow ...
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Is there any molecule describable by three-level with mixed parity and transition dipole moments in different directions?

I would like to know if there are molecules described by a three-level system with mixed parity and transition dipole moments in different directions. By mixed parity I mean all three transitions can ...
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Is this online fluorophore database reliable?

I need fluorescence spectra for various fluorophores in certain dispersion media for some calculations. There is an online database of University of Arizona: http://www.spectra.arizona.edu/ Is using ...
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What are the requirements for FRET?

I have a question about fluorescence resonance energy transfer (FRET), and the requirements needed for this technique. Q: Which of the following need to be met for FRET? A) Strong overlap ...
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What is special about the molecule luciferin that it can emit light?

A classic example of bioluminescence; the protein luciferin is oxidized by the enzyme luciferase, releasing energy as light. What is it that gives luciferin this ability? Why can't just about any ...
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Is there a chemical which fluoresces only after coming in contact with water? [closed]

I require an easily available chemical compound which in its pure form, does not fluoresce under UV light. However upon coming in contact with water (at room temperature) it fluoresces under UV light....
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Why do fluorescence intensities decline with replicate number?

I am performing a determination of riboflavin with fluorescence spectrophotometry. I've dissolved my riboflavin in a dilute GAA solution, created a calibration curve and measured my unknown's ...
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Thermochromic, fluorescent fluid

I'm a total layman in chemistry and am working on an interactive sculpture project and therefore am researching into fluids that have certain properties - long story short: we are thinking on having a ...
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Compound with a bright green emission when electrically excited

I rolled back the edit because I really am looking for the following: I am looking for an element or compound that would have a bright green emission when electrically excited and is a gas at between ...
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What makes a species “fluorescence quencher”?

I just came across an article where they said that sodium fluoride is not quencher (in the context of fluorescence). Why is NaF not a quencher but NaBr is one?
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What should the Rehm-Weller equation look like?

The Rehm-Weller equation, which defines the energy change for photoinduced electron transfer according to Lakowicz "Principles of Fluorescence Spectroscopy" [1, p. 337] should look like: $$\Delta G=E^...
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Interpretation of Figure - biofunctionalization

In this paper on page 1985 they say: Fluorescence analysis confirmed that enhanced protein binding at higher electron dose depends only to a small extent on the slight increase in the lateral ...