Questions tagged [fluorescence]
For questions relating to the radiation emitted by substances as a result of incident radiation.
84
questions
2
votes
1
answer
576
views
Is the XRF spectroscopy equally sensitive for every element?
I am curious whether or not every element can be equally well detected by using X-Ray-fluorescence-spectroscopy. Might there be any contitions or circumstances that make it hard/impossible to detect a ...
- 105
2
votes
2
answers
1k
views
Why do some molecules show non-symmetric absorption and emission bands?
I'm looking at a molecule of [Ru(bpy)3]2+ in water and the absorption and emission bands are not symmetrical. I want to know why the mirror image rule doesn't apply here. Is this because of the MLCT, ...
- 23
5
votes
1
answer
198
views
Nitrogen dioxide fluorescence quenching and lifetime
Nitrogen dioxide fluorescence quenching:
$$
\begin{align}
\ce{NO2 + h\nu &->[$\varphi_\mathrm{Ia}$] NO2^{\ast}}\tag{I}\\
\ce{NO2^{\ast} &->[$k_2$] NO2 + h\nu'}\tag{II}\\
\ce{NO2^{\ast} +...
- 65
1
vote
1
answer
100
views
Are there any fluorophores with lifetimes in the micro to milli second range?
I'm looking for a fluorophore with exceptionally long lifetime to use in an oxygen optode (the longer the lifetime the less timing precision needed in the electronics).
So far the longest I have ...
- 553
5
votes
1
answer
255
views
Deriving fluorescence intensity equations
I've been having trouble with deriving the equations in the following problem.
The interaction between DNA and AO to form the AO–DNA complex can be expressed by the following reaction:
$$\ce{...
- 605
1
vote
1
answer
565
views
Latent blood detection with fluorescein
I need help with the reaction between fluorescein and blood in the method of detecting latent blood stains.
I find it hard to find any literature on this subject.
As far as I am concerned, the ...
0
votes
0
answers
43
views
When an electron is excited to a singlet state, must it flip its spin state to enter the triplet state and flip once more to the ground state?
I understand the Jablonski diagram in that it has intersystem crossing from the singlet state to the triplet state, but how many spin switches are necessary to complete to phosphores? When an electron ...
- 21
0
votes
0
answers
204
views
Is the activation energy always inversely proportional to the reaction rate?
When I obtained the activation energy using the Arrhenius equation for a 10-minute glowstick (rapid, rigorous reaction), it was almost 4 times that of a 12-hour glowstick (slow, mild reaction).
...
- 143
0
votes
1
answer
129
views
Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf? [closed]
I'm stumped by this question:
Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf?
I've thought that it might have something to do with how sun emits light ...
3
votes
1
answer
436
views
How to calculate molecular emission spectra?
Is there free software that 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://...
- 673
0
votes
0
answers
73
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 ...
- 9
4
votes
1
answer
2k
views
Why are glow-in-the-dark things usually 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 ...
- 6,771
6
votes
2
answers
618
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.
...
- 6,771
4
votes
2
answers
186
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 ...
- 1,257
1
vote
0
answers
458
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 ...
- 1,410