Questions tagged [fluorescence]

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

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84 views

How to calculate molecular emission spectra?

Is there free software which can calculate the fluorescence emission spectra of organic molecules? Let's say for example: rubrene There is a bunch of quantum free quantum chemistry software: https://...
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48 views

Does something like a fluorescent foil or a fluorescent film exist?

During my experiments I want the emitted laser beams to come back with a different wavelength than the original wavelength using a fluorescent foil or fluorescent film. The laser I'm currently using ...
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1answer
132 views

Why are most glow-in-the-dark things green?

I've noticed that many glow-in-the-dark objects you can purchase in the store are green. Occasionally I would come across something that was orange or blue, but mostly it seems that green is the ...
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2answers
146 views

Why do glow-in-the-dark substances dim gradually?

Related: How do things glow in the dark? Growing up, I had glow-in-the-dark stars on my ceiling and after being "charged" by having my lights on, they would phosphoresce for quite some time. However,...
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2answers
60 views

Measuring a high Michaelis constant using fluorescence

We have the task of measuring kinetic parameters of an oxidase reaction that has a $K_M$ of about $2 \,\text{mM}$. For that, we want to use a fluorescence assay based on Amplex Red. The latter is a ...
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38 views

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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45 views

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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2answers
69 views

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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1answer
150 views

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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1answer
63 views

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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3answers
72 views

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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1answer
31 views

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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1answer
116 views

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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165 views

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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80 views

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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2answers
247 views

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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1answer
118 views

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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32 views

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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1answer
946 views

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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39 views

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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2answers
66 views

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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3answers
463 views

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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872 views

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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63 views

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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1answer
284 views

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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1answer
104 views

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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1answer
136 views

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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2answers
1k views

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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4k views

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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161 views

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 ...