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Questions tagged [photon-emission]

This tag is for questions regarding to Photon Emission. Photons are emitted by the action of charged particles, mainly due to making a transition from a high energy state to a lower energy state. Although they can be emitted by other methods including radioactive decay.

When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level. $$\text{E}_\text{photon}=\Delta\text{E}_\text{electron}=\text{E}_\text{upper}-\text{E}_\text{lower}$$

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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 state gets converted into a lower one by the emission…
user73837
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How does an electron absorb or emit light?

It's a common understanding that atoms emit or absorb light when the energy of the photons is equal to the the difference in the energy levels in the atom. What I don't understand is how does an electron absorb light inside an atom? Is it that the…
lattitude
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Stimulated emission and No-cloning theorem

I have a little trouble with the simulated emission. I know of the no-cloning theorem which states that it is not possible to duplicate any state. One the other hand, I know about the stimulated emission which out of a photon produce exactly the…
sailx
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What determines if a lamp produces emission or blackbody spectra?

If we take a lamp containing hydrogen gas and heat it up (gas-discharge lamp), it produces hydrogen's emission spectrum. Why doesn't it produce a blackbody spectrum? After all, the gas has some temperature, and that allows for a blackbody…
Allure
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Does the diffracted electron radiate photons?

When electron is diffracted after the slit it might follow different direction, than before the slit. That means, that going through the slit it gains some acceleration. And accelerated charge emits photons. Thus - does the diffracted electron…
Paweł Tokarz
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Why don't absorption and emission lines cancel out in our Sun?

I was looking at this answer on why absorption lines and emission lines don't cancel out: An experiment shining light on the material and looking at the reflected spectrum will see absorption lines at those frequencies, because the relaxation…
macco
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What happens to the non-axial photons of a laser cavity?

When a laser cavity is pumped, the axial photons are reflected back and forth by the cavity mirrors and so contribute to stimulated emission, but the non-axial photons do not have this opportunity. What happens to these non-axial photons?…
The Pointer
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How is light emitted by an incandescent lamp?

I am looking for better understanding of how light is produced in an incadescent lamp. More specifically: how is the kinetic energy of electrons converted to light? Are we dealing with interband transitions or with intraband relaxation involving…
Roger V.
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Why absorption spectum is not identical to emission spectrum?

Hydrogen emission and absorption spectral lines are typically depicted as the same: (source) However, in more complex systems, the emission and absorption spectra are significantly different. For example: Absorption and photoluminescence spectra…
Sparkler
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Why can Einstein coefficients be derived based on thermodynamically equilibrium relations when they are basically intrinsic?

Einstein coefficients for emission and absorption ($A_{21}$, $B_{12}$, $B_{21}$) are often derived from a consideration of thermodynamic equilibrium using Boltzmann statistics and comparison with Planck's law. This (among many others) is the typical…
MichaelW
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Photons of a radio wave

It has been said that RF consists of IR photons (here (now deleted; screenshot) however opinions seem to differ): The smallest energy for photons is in the range of the infrared radiation. Longer wavelengths are related to modulated EM radiation…
Eugene Ryabtsev
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Integration & bremsstrahlung calculation

In this paper (relevant pdf section) that I'm reading, involving the calculation of bremsstrahlung in electron proton scattering (diagram below), the author calculates the integral over outgoing photons and scattered electron: $$\tag{III.10} A=\int…
Nathaniel Bubis
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How "wide" are absorption and emission lines?

There are various absorption lines that correspond to the difference in energy levels between electron orbits. E.g. the https://en.wikipedia.org/wiki/Lyman-alpha_line correpsonding to the difference in energy between an electron orbiting a hydrogen…
blademan9999
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Does each spectral line of an atom/molecule have a unique lineshape?

A spectral line is determined by a particular transition in an atom or molecule. In reality, this line isn't infinitely sharp, but has a small distribution about the resonance frequency as a result of a few things. This distribution will have a…
compp
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Why is $K_{\alpha,3/2}$ always more intense than $K_{\alpha,1/2}$ in copper?

Consider characteristic X-ray emission from copper. The $K_{\alpha}$ line is a doublet because of the spin-orbit interaction. But why is the $K_{\alpha,3/2}$ line always more intense than the $K_{\alpha,1/2}$?
Sørën
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