Questions tagged [fluorescence]

This tag is for questions relating to "Fluorescence", an optical phenomenon in which the molecular absorption of energy in the form of photons triggers the emission of fluorescent photons with a longer wavelength.

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1answer
29 views

Spectrum of laser light absorbed and re-emitted by a white object

If I shine a red laser onto a white surface, I assume that: some of the red light will be nearly instantly reflected, some will be absorbed and converted into phonons and some will be absorbed and re-...
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11 views

Would UV-induced-visible-fluorescence indicate the presence of vividly reflecting UV-invisible-light?

Some people take amazing photos by using UV-induced-visible-fluorescence(UVIVF). In my understanding, we see in these photos VISIBLE light induced by UV. https://www.nationalgeographic.com/photography/...
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1answer
47 views

If not fluorescence, what is the process of emission and absorption of white light by everyday objects?

An electron in an atom is excited by a photon and moves to a higher energy state. The electron then relaxes and transitions to a lower energy state emitting a photon of longer wavelength than that of ...
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23 views

Confused about Rabi oscillations method

I am a bit confused about how the Rabi oscillations method is applied in practice. The probability of producing a transition (assuming the atoms start in the ground state and we ignore the lifetime of ...
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1answer
39 views

How do Fluorescent molecules emit light in a different wavelength than the one needed to excite them?

if it took a very certain amount of energy to excite an atom, how come when it de-excites it emits a photon of lower energy? I know that's what scintillators do, I Just want to know the microscopic ...
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1answer
22 views

Looking for ideal calibration standards for UV / visible fluorescence

I am attempting to measure the fluorescence timing distribution (how much light is emitted over time from initial excitation) of a substance and I would like to use a solid calibrated sample (some ...
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22 views

Reconciling two descriptions of fluorescence

I am currently studying the textbook Infrared and Raman Spectroscopy: Principles and Spectral Interpretation, second edition, by Peter J. Larkin. Section 9. Selecting the Raman Excitation Wavelength, ...
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1answer
34 views

Is there any equivalence or “fluorescence” in acoustics?

Fluorescent materials convert some visible or invisible electromagnetic radiations from a certain range of frequencies to another one, usually from higher to lower frequencies, rarely, the other way ...
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23 views

Is the Crookes tube with Maltese cross (cathode rays) safe in terms of produced X rays at 5-10kV DC (1–10mA) during, say, 15 seconds of work?

I would like to get some information on the operational safety of this equipment. How much, approximately (just the order of magnitude) does the school Crookes tube with the Maltese cross, used to ...
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14 views

What is the mechanism responsible for Oxygens quenching of fluorescent compounds?

How do the oxygen molecules cause the drop in fluorescence used in oxygen optode sensors? The Quenching(fluorescence) wikipedia article lists five different mechanisms and elsewhere in the article ...
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40 views

Simluation of time-resolved fluorescent spectrum

I'm trying to model time-resolved fluorescent spectrum of diatomic molecules. My questions concern some formulas in "Atoms, Molecules and Photons An Introduction to Atomic-, Molecular- and Quantum ...
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1answer
120 views

Electronic-vibrational-rotational Transition

I'm trying to simulate the fluorescent spectrum for the first time and run into several problems. The dipole matrix element for a transition between 2 different electronic states is as follow: $$\...
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1answer
25 views

If a fluorescent atom absorbs UV and emits visible light, then how is energy conserved?

Light has a lower frequency than UV, so unless energy is also released in other forms, how can energy be conserved? What other forms is energy released as for fluorescence?
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214 views

What is the difference between lasers and fluorescense?

In both cases I see few low energetic levels, few upper energetic levels, some no-emission transitions between upper levels and main downwards transition called either fluorescence or laser. Here is ...
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1answer
29 views

Why fluorescence lifetime in laser crystals decreases while dopant concentrations increases?

I noticed, that is laser crystals the low levels of doping are used and that if higher levels did, the lifetime of excited level will be shorter. Why? The atoms of dopant are the same. Why do they ...
4
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1answer
120 views

Can phosphors exhibit stimulated emission?

I read that phosphorescence is caused because of the presence of "forbidden" energy states. This causes the photon that is absorbed to not be immediately emitted like fluorescence but emitted after a ...
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1answer
112 views

What causes a light bulb to fluoresce?

When an incandescent light bulb or fluorescent light bulb is pumped up with energy from the power grid, presumably light is subsequently emitted via transitions from the molecular excited state to it'...
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48 views

Can (diatomic)fluorine gas discharge tubes be used as a UV light source?

Looking at the emission spectrum of fluorine there are 2 sharp peaks in teh far ultraviolet band. I haven't been able to find any direct images/articles about fluorine gas discharge tubes being used ...
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18 views

Optimal paint for UV fluorescence?

If we assume that a light source with 365 nm is the optimal source for how strongly we perceive UV light when it hits a UV fluorescent surface, what would be the optimal colour to paint such a surface ...
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1answer
47 views

Is it possible to make a fluorescent material that only glows in response to a specific UV wavelength?

There are any number of fluorescent materials that glow when exposed to UV light. But what if I wanted such a material that only glows in response to very specific wavelengths, emitting no visible ...
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1answer
25 views

fluorescence wavelength limit

My understanding is that fluorescence occurs when light has sufficient energy to excite an electron, which then emits a different photon (always with a larger wavelength) and releases the energy it ...
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76 views

What is the nature of vibrational relaxation in fluorescence?

Electrons in fluorescent substances get excited from the ground state($S_o$) to the first excited state($S_1$) or higher excited states in case of upconversion. Depending on the statistical ...
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0answers
38 views

Timescales of plasma recombination and fluorescence?

I am currently working on a very simple model for the radiation from electric arcs. As both fluorescence (internal electronic transition) and plasma recombination occur, I would like to compare the ...
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1answer
64 views

Photon Spin in Fluorescence and Phosphorescence

I think i still lack basic understanding of how absorption and emission of light actually works. Like fluorescence is the radiative transition from an excited singlet state to the ground (singlet) ...
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Requirements for a fluorescent medium to provide optical gain

I have seen fluorescent material such as Rhodamine 6G being used as a gain medium in dye lasers. My understanding is that by pumping the medium with energy, we can make stimulated emission happen ...
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3answers
51 views

Why is there not a solid state fluorescent lamp?

Is it possible to coat a solid piece of metal with fluorescent powder (such as in a tube), and get this to emit light in a strong electric field?
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1answer
46 views

DNA - optical response and fluorescence

I am curious about the state of affairs with the DNA fluorescence. I know that there was some initiative in physics community in 1980's and 1990's, but some authors question even whether DNA molecules ...
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If blackbody radiation at 6000K peaks in the optical, why aren't fluorescent bulbs at 6000K?

We know, via Wien's law, that a body at 6000K emits an electromagnetic wave at the peak wavelength in the visible spectrum. How come say the fluorescent tubes which also emit the EM waves that we can ...
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24 views

Fluorescence photons per event

When a high-energy photon hits a material that fluoresces, what formula can you use to determine how many photons will radiate out as the material de-excites? I would like the most general formula ...
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56 views

Cannot observe Raman signal from Styrofoam

I am trying to build a low cost Raman spectrometer. I am using a refurbished B&WTek spectrometer that I purchased from eBay. I calibrated the unit myself and found to be very sensitive and ...
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52 views

What are some mechanisms that can lead to unexpected/anomalous spectral lines

I am studying fluorescent spectroscopy (laser-induced fluorescence spectroscopy specifically). In a particular atomic spectrum, there are some unexpected lines not associated with any known ...
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1answer
340 views

Can a plasma ball light up minerals that fluoresce?

I want to know if I could use a plasma ball to light up a UV poster that are typically activated by blacklights. option 1: using light from the globe According to my research it seems that the light ...
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0answers
41 views

Two-photon absorption fluorescence of air

I'm wondering if there are any major constituents of air which are capable of undergoing two-photon absorption and ultimately fluorescing in the visible spectrum. The original wavelengths of the ...
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1answer
65 views

Fluorescence or phosphoresence?

Is there any theoretical way to know if a material emits a fluorescent light or a phosphorescent one? Is there any relationship between this process and the singlet-triplet energy splitting $\Delta E =...
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1answer
445 views

Raman Scattering vs. Fluorescence (1-photon / 2-photon process) [duplicate]

I have a question considering the difference between Raman Scattering and fluorescence. I know that Raman Scataring is a non-resonant process, while fluorescence is resonant, that Raman scattering ...
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369 views

Why is a white LED color spectrum more continuous than CFL spectra?

As far as I understand, white LEDs and CFLs both use phosphor mixtures to convert part of their primary emission spectrum to longer wavelengths. What puzzles me is the difference in the resulting ...
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75 views

“Fundamentalrelation of Resonance Fluorescence” - How can it be?

In my quantum optics lecture, I was given the formula: $$ \vec{d}_{eg} \hat{\vec{E}}^{(+)} = \frac{i \kappa \hbar}{2} | g \rangle \langle e | $$ Here, $\vec{d}_{eg} = \langle e | \hat{\vec{d}} | g \...
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1answer
134 views

Is it valid to compare experimental data and theoretical data like this? Does the vertical axis of the graphs have to correspond?

The plotted curve is the experimental value of the SPD curve. Though it doesn't look "spikey" as it should, stacking the image on top seems to explain that the data is infact correct, but that more ...
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1answer
358 views

Can heat cause flourescence or phosphorescence at STP?

I am aware that chemical reactions may cause fluorescence. Most fluorescence results from adding light and then watching the captured light re-emit. Is there any that doesn't require adding light, ...
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3answers
3k views

What are these alternating bright and dark rings in fluorescent lamp?

I'm quite surprised by these regularly spaced rings of alternating brightness in a fluorescent tube. These are also moving along the tube and only appear when the voltage is low. What are these and ...
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0answers
42 views

Limits single fluorophore, simultaneous absorption and emission

So I've been trying to find out what the limitations are for single fluorophores. What I know is that a fluorophore is excited by a photon in too a higher excited state, it then relaxes and later ...
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0answers
86 views

Collisional quenching in fluorescence

I am studying collisional quenching phenomenon in fluorescent measuring and I am focusing on Stern - Volmer relationship. I can't understand why the ratio of the intensities of fluorescence is equal ...
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1answer
76 views

Can we have a three-level system 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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0answers
35 views

What upconversion phosphor is this?

Is there a way t know which upconversion phosphor was used to create this? The original flickr image doesn't offer any information. If this is impossible, where can I find any images demonstrating a ...
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1answer
348 views

Uranium-doped solid state visible lasers - feasible?

It is known that uranium glass shows strong green fluorescence under near UV illumination which could promise green lasers without non-linear crystals. Is it feasible to build Uranium doped laser (...
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1answer
632 views

Raman vs Fluorescence, scattering vs absorption, classical vs quantum [duplicate]

I am trying to grasp the difference between Raman scattering and fluorescence. To me it appears that the former is described in a somewhat more classical context as ordinary inelastic scattering, ...
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23 views

Discharge on fluorescent light

when the voltage is very low, fluorescent lights will not light fully as the voltage is not enough to generate a discharge. But I could see a glow at both the ends. When I touch on the outside of the ...
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1answer
154 views

Which of these reasons are causes for the Stokes effect in Raman Scattering and/or Luminescence?

I’ve read several reasons for the Stokes effect and I can’t make out which of these are the true causes. Which of these apply to Raman or Luminescence or both? Are some of these the same thing? 1. ...
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2answers
367 views

How is the resolution of a Laser Scanning Microscope defined?

I am reading about the image formation process in fluorescence microscopy, and I am puzzled by a question. Why the axial resolution of a Laser Scanning Microscope depends on excitation wavelength, but ...
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What are the energy levels responsible for CdSe's fluorescence

Fluorescence is when a material absorbs photons of one wavelength and radiate photons of another wavelength (necessarily lower due to conservation of energy, assuming the material is unchanged). CdSe ...