Questions tagged [photon-emission]

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1answer
34 views

Does shaking an atom produce photons?

I have a vague recollection of a description of the relationship between matter and light. It went something along the lines of this: "Grab hold of a thing and ...
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0answers
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Why cannot we see back of our head? [duplicate]

Suppose we are watching a star at night, we are able to see that star because the photons from that star reach our eyes, now since the photons emitted by that star will reach earth and if we ...
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1answer
28 views

How can the oscillating states of many atoms in a lattice combine to give even a larger number of possible states?

Basically, I was studying the band theory and there was that thing that I couldn't understand, and it appeared to be connected to another question: how is the blackbody radiation appear continuous ...
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24 views

What causes a double peak for a single wavelength when using an optical spectrometer system?

I am doing an experiment to determine the Rydberg constant for the Balmer series using an optical spectrometer system (consisting of a monochromator with a photomultiplier detector and pulse counting ...
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1answer
19 views

How do the electrons absorb energy in an discharge tube that is used for produce an emission spectrum?

When there's hydrogen in a discharged tube it produces an emission spectrum, emitting energy(photons). (Eg:-When an electron jumps from 3rd energy level to 1st energy level, the electron emits a ...
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Hydrogen discharge tube emission spectrum different from emission during burning

In "How is it possible some substances burn with an invisible flame" it is stated that light emitted from burning hydrogen is almost invisible, more precisely: You say that hydrogen flames are ...
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2answers
72 views

Photons confusion

Suppose for a particular electric transition an electron absorbs a photon of energy $hf$. Now my doubt is can't the electron for the same transition absorb 2 photons each of energy $hf/2$ i.e, each of ...
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2answers
33 views

It is possible to have photon emission when measuring state of an atom?

Suppose in the hydrogen atom we have a state $$\Psi=a\phi_1+b\phi_2$$ where $\phi_1$ is the ground state, $\phi_2$ an eigenstate different from the ground state and $a$ + $b$ constant such that $$a^...
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Theoretically and experimentally investigation of $n$-photon sources?

Spontaneous Parametric Down-conversion (SPDC) is an indispensable ingredient for producing both entangled photon pairs and heralded single photons. I call the SPDC nonlinear crystals as 2-photon ...
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1answer
15 views

What is condition for emission spectrum?

Deexcitation of electron gives us emission spectrum but in my book states it's only possible if $\Delta n\ne 0$, $\Delta \ell=\pm 1$, $\Delta m=0,\pm 1$.
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1answer
134 views

Frequency plot with photoelectric current and anode potential

Keep your eyes near 0V anode potential - here you can see that the light with maximum frequency has more photoelectric current and that the light with minimum frequency has less photoelectric current ...
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Energy and momentum conservation in ARPES

In ARPES experiment we assume that electron's momentum in-plane component is conserved, while perpendicular component - NOT. This means what total momentum of electron |K| changes, which means that ...
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1answer
105 views

Which color in emission spectrum do we really see?

For example, potassium has this emission spectrum according to google image It is typical (and kinda necessary) for atoms to have multiple emission lines, so what determines which color we actually ...
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1answer
47 views

Why hydrogen emission spectrum is discrete?

It is generally known that the emission spectrum of hydrogen is discrete, which is usually explained as follows: when a photon is emitted, the atom jumps to a lower energy eigenstate, the energy ...
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1answer
24 views

Thermal emission from a metal surface

We know from Kirchhoffs law that at thermal equilibrium the absorbance is equal to the emissivity. Let's consider some opaque layers of Al, Ag, Au for which I found reflectances at google: When I ...
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2answers
95 views

Why the emitted photon has exactly the same energy,phase and direction as the incident photon in stimulated emission?

My textbook says:- When an atom emits a photon due to its interaction with a photon incident on it,the process is called stimulated emission.the emitted photon has exactly the same energy,phase and ...
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1answer
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Troubles with stimulated emission of single photons and the no cloning theorem

I think I don't understand something basic about stimulated emission: it seems to violate the no cloning theorem, and applying its arguments give me 2 different results when trying to understand a ...
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1answer
48 views

Does linear momentum of a hydrogen atom-system remain constant during electronic transitions?

When electronic transitions(excited to ground) take place in a hydrogen atom, does the linear momentum of proton-electron system remain constant?
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1answer
232 views

What is the difference between scattering and absorption/emission?

As far as I know, scattering occurs when light excites the atoms or molecules to their higher energy state(virtual state for scattering) followed by emitting photons corresponding to energy ...
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2answers
43 views

How will the uncertainty principle broaden emission spectrums?

I have been told in a lecture that the broadening of peaks detected from photon emission in a hydrogen lamp is due to the uncertainty principle, but can’t work out how it does or find any equation ...
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2answers
90 views

Mass reduction due to emission of photons

when a torchlight emits a photon of energy E, will its mass reduce by (E/C^2) according to mass energy equivalance? if no what will be the reduced mass?
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1answer
105 views

Photoelectric current vs anode potential

Attached is the graph of photoelectric current vs Anode potential as given in my book for same intensity and different frequencies of incident light for the same metal(hence same work function). In ...
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1answer
64 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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15 views

Does emission-spectrum of molecule equal sum of emission-spectrum of its components

Imagine a number of elements with known emission-spectra, that form a primary chemical bond of either * ionic * covalent * metallic type. Does the emission-spectrum of the resulting molecule match the ...
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2answers
131 views

How do materials absorb light

I'm curious how light is absorbed in materials. From what I understand, when an electron absorbs a photon, it gets excited to an energy level that is higher than the level it's in and the energy ...
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100 views

Are there names for Helium (He) emission lines like the Lyman/Balmer/Paschen series in Hydrogen?

Just wondering if helium emission lines have names like hydrogen lines. For instance the Balmer series is: $$H_{\alpha}, H_{\beta}, H_{\gamma}, H_{\delta}...$$ The Lyman series is: $$L_{\alpha}, ...
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1answer
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Light matter interaction (LASER) [closed]

I don't understand how a photon energy get absorbed or emitted by a electron. when photon incident on electron it absorbs photon energy and go to excited state, and when it come down it emits energy. ...
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1answer
229 views

Times associated with Absorption and Emission Processes

I am currently reading the book "Advances in Atomic Physics: An Overview" by Cohen-Tannoudji and Guéry-Odelin. In pages 29-31 the authors discuss a two-level atom subject to a broadband radiation ...
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1answer
107 views

Photon creation operator physical realization

I am trying to self study QED so I apologize if my question seems silly. As I realize, all physical processes should stem from some "hermitian" operator in the quantum language. As it is well known, ...
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1answer
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Why does wavelength coherence affect diffusion?

Not to be confused with the relationship between wavelength and photon localization. But, laser light is is able to stay concentrated over a vast distance, much more so than every-day lamp light. ...
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Database of Color Emissions

I am reading about the color Green and am wondering if there is a database anywhere listing the atoms/molecules/powders/minerals and their color wavelengths in various forms. Basically I would like a ...
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2answers
98 views

What is electromagnetic radiation (when it is not a 'wave' of EM fields or interacting locally as a photon)?

My questions are related to the question asked at Are EM radiation and EM waves the same thing?. My background is in math (my Ph.D. thesis was in geometric analysis), and I have only taken basic ...
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Why does a hot bulb filament emit photons? [duplicate]

Heating up a bulb filament provides energy to the filament material thus exciting the electrons. So how does excitation of electrons release photons generating light since excitation of an electron ...
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1answer
39 views

Free electron laser has really free electrons?

I have read this: https://en.wikipedia.org/wiki/Free-electron_laser This states that electrons are free. Now there is a debate on this site over whether a truly free electron in vacuum can or ...
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1answer
50 views

When a valence electron is excited, how fast does it move from ground state to excited state?

Imagine an atom with a valence electron becomes excited and the electron moves to a higher orbital, is this transition between ground state and excited state at speed of light? If so, since it is not ...
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Laser Detection Paint

Does there exist a paint which if a pulsed laser of ~1500-1600nm was fired at it it would emit visible light or IR Radation (3-5 micron)? I have seen up-converting inks and paints but I can't find ...
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2answers
71 views

Why does the motion of the emitter (doppler shift) impact the energy of the photons

(a) When there is a red or blue shift, is there an actual change in the energy of the photons or not? (b) If there are two observers, one moving toward the light source and one away from it, they ...
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1answer
54 views

Is thermal coupling to a too cold thermal background impossible?

In (Krauss & Starkman 1999) the authors critique (Dyson 1979), and in one section argues that in the very far future cooling will become impossible because thermal contact with the cosmic ...
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1answer
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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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4answers
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Why do atoms (iron eg) glow with all frequencies of light when exposed to enough thermal radiation?

Correct me if I'm wrong, but objects (made of constituent atoms) glow with a particular frequency of light which our eyes relate to as colour. They glow when a particle in a higher energy quantum ...
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5answers
84 views

Why is visible light observed as confined to its source?

When I observe a visible light source, like the sun or a light bulb, why do I observe the light source as a confined object? Like why is the sun or a bulb or whatever seen as a confined ball of ...
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1answer
94 views

Number of photons in a range of wavelengths

I need to calculate the number of photons in a beam of light of power $P$. I know that it has constant power $P$ across the range of wavelengths $[\lambda_1,\lambda_2]$. So, for calculating this, I've ...
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4answers
523 views

What happens to the spin when photon is absorbed by an electron?

Photon is spin 1 and electron is spin 1/2, so when a photon is absorbed by an electron it is destroyed and the electron becomes excited by that amount of energy. The next moment the electron will go ...
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1answer
64 views

How/Why does heat radiation work, atomically?

In this question the relationship between characteristic spectral lines of elements and the apparently continuous emission of blackbody radiation was examined. It was suggested in the answer that ...
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0answers
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Why are there no excitations by collision for the visible transitions in the Franck-Hertz experiment?

The minima of the I(V) graph for a Neon Franck-Hertz tube are approximately 20V apart from each other, this is usually explained by the fact that excitation by inelastic collision happens at about 20 ...
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1answer
92 views

Is there any difference between Photon produced from proton and electron?

I know that accelerated charged particle produces Photon but is there any difference between photon produced from a positive and negative charge?
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Localization of photon

Is the photon localized at the instant of its Emission (release)? by an accelarating charge by Atom´s emission
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2answers
203 views

In diffraction When wavelength is less than slit width then does the scattered light gets absorbed & emitted from the wall or just rebound?

I know that when the slit width is less than that of wavelength then the slit will act as a point source and scatter the light in all directions. But my question is that during the scattering of ...
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4answers
122 views

What determines the color of the light emitted in a Tokamak?

We see images of Tokamak plasma with all sorts of colours from red to purple. Why do we see any light at all, since the plasma should be so hot to have dissociated all its electrons? It is all from ...
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5answers
81 views

What stops a free electron from 'using' part of its own mass to generate radiation?

The explanation I've read on why a free electron can't emit a photon goes like this: Let there be a free electron of mass $m$ moving with constant velocity $v$. We may enter a new reference frame ...