Fluorescence Definition and 73 Threads

Could You simply define what fluorescence blinking is? Thanks,

Is the term "fluorescence" limited to emission of visible light? (If the emitted light is IR, would this not be fluorescence?) In many demonstrations, UV light is absorbed and visible light is emitted, but is absorption of UV an essential feature of fluorescence? Or could it also be a...

Hello, I think the general operational theory of fluorescence is understood - a molecule accepts a photon, its electrons are excited from the ground state to a higher energy state, and, as they return to the ground state, they emit EM waves which we see as light. My question is what makes...

If the fluorescence is the re-emitting of a photon with a larger wave length due to the transition from a higher energy state to a lower energy state in the case of resonance Raman (where there aren't any virtual states) seems be equal to the fluorescence. Which differences are there?

Today in lab we performed two different chemiluminescent reactions - one involving the oxidation of luminol with H2O2 in a CuSO4 solution and the other the oxidation of luminol with H2O2 in a hemoglobin solution. My question is, why would there be a difference in the duration of the...

My question is, when extracting the count rate from a particular peak in the energy dispersive spectrum (e.g. X-ray fluorescence) Is this done by simply drawing a straight horizontal line from the top of the peak to the y-axis and the corresponding intercept will be the count rate? What if the...

I'm currently working on a lab that is exploring the Raman effect. One of the suggested exercises was to record the raman spectrum (from a mercury lamp through CCl4) around the rayleigh peaks at 435.8 nm and 404.7 nm. For the former, my results were fairly consistent with what I expected in that...

Homework Statement Consider a hypothetical semiconductor with band gap 1eV, Relative electron mass is 0.05 and relative hole mass is 0.5. In a cube-shaped quantum dot of this material with side length L = 3nm, what is the energy associated with a transition from (2 1 1) electron state to...

1. Homework Statement calculate the angle between the absorption dipole and the emission dipole of specific blue maleimide ? limiting polarization was determined to be 0.5 and anisotropy 0.4 Relevant equations I know from lectures that the angle should in fact be zero because the actual max...

Hi There, I have been working on fluorescence decays of the fluorophores whose lifetimes are comparable to the instrument response function(IRF) of my device. The technique I use is based on Time-correlated single photon Counting(TCSPC). I have been fitting the decay curves using...

Homework Statement I am doing some research for a lesson pertaining to the fluorescence of chlorophyll. When chlorophyll has been extracted from plant leaves using acetone, the solution will glow a bright red when exposed to UV light. My question is: what is the physical cause for...

Hi, I'm doing some calculations on fluorescence and I'm a little stuck on statistics. Let's say I need to measure 20 seconds to collect 10000 photons from a single molecule. Then I can say well I want to measure at most 1 second and therefore I need 20 molecules in order to collect 10000...

Hello there, I'm going through the derivation for the equations relating to frequency-domain lifetime measurements for fluorescent samples. This is a technique whereby a sinusoidally-modulated light source excites a fluorescent sample, and the fluorescence lifetime of the sample, \tau is...

I all, I am afraid of abusing the dictionary now, but by fluorescence I mean excitation and immediate emission. By phosforescence I means excitation and after a randomic time that can be of the order of minutes, the atom emits. I woud like to confirm if the names are correct and if there is...

Homework Statement I understand that in the fluorescence, the incident photon is absorbed by the molecule, and the molecule while returning to its original ground level releases lesser energy. Similarly, in Raman effect also a photon is incident on a liquid molecule. In stokes' lines the...

First of all, I'm not the one doing this experiment. I've just finished my first year in college and I'm sort of just helping all the upper-level with their research and whatnot. So my knowledge is very limited. With that being said, one of those student is doing X-ray Fluorescence. He was...

I did a bit of x-ray spectroscopy in labs studying Fluorescence of some different elements. I was just wondering whether or not flourescence occurs in all elements? I'm sure I've read people talking about 'flourescecnt materials' or something like that. I can't think of any reason why it...

Hi, I have a quick question on fluorescence. I have fluorescein molecule. Its absorbance is pH sensitive. However, I want to know if 1. It emits fluorescence. 2. the fluorescence intensity pH sensitive I know for sure it emits fluorescence. I see, what I believe to be an emission...

Hi, I am doing an enzyme kinetic study and I am having problem with the fluorescence reader I am using. It is a Varioskan from thermo. When I start the reaction with the substrate (using a dispenser), the fluorescence signal changes to 0 after a few seconds. It doesn't happen in all wells...

The noble gases when electrically stimulated emit different visible wavelengths. Can they be combined for a greater variety of coloration?

many biological molecule can emit fluorescence. but is the quantum field of these molecules large? can u give me some examples that the molecule emits strong fluorescence, such as beta-carotene? for this field ,i know little. thank u

What is fluorescence and how does it arise? Is it just a spontneous de-excitation after the electron in the molecule (protein) has been excited. This is a 6 mark question in last years Chemistry-2 exam and i don't really know how to go about answering it. Any suggestions?

What is fluorescence and how does it arise? Is it just a spontneous de-excitation after the electron in the molecule (protein) has been excited. This is a 6 mark question in last years Chemistry-2 exam and i don't really know how to go about answering it. Any suggestions?