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.

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A question on emission spectrum and two-time correlation function

Here, the expression of the emission spectrum is $$S(\omega)=\int_{-\infty}^{\infty}\langle A^\dagger(t+\tau)A(t) \rangle e^{-i\omega\tau}\text{d}\tau=2\Re\left\{\int_{0}^{\infty}\langle A^\dagger(t+\...
Young Q's user avatar
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What happens to light absorbed by a body with color?

As everyone knows, an object with color appears that way because it reflects its specific color(s). Textbooks tell us other colors are absorbed. Now, here's the question: what happens to the absorbed ...
MegrajChauhan's user avatar
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Stimulated emission semiclassical model for atom recoil

In the context of Saturated absorption spectroscopy, I'm having trouble modeling stimulated emission, and getting the result that is written in articles, such as this article. I tried to use a non-...
Doron Behar's user avatar
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Is it possible to model unidirectional evolution of an atom-photon system using the Schrodinger equation?

The physical system I'm imagining is pretty simple: suppose there's an atom in free space with three states $|g_0\rangle, |g_1\rangle, |e\rangle$ initialized to some superposition of $|g_0\rangle$ and ...
whooie's user avatar
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1 answer
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What is the intuitive reasoning for Stimulated Emission?

I've been scouring the web for explanations of Stimulated emission, and have seen questions Like this one on directions and frequencies, this one on energy conservation, this one one lasers and ...
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How Does Laser Light Maintain Coherence Amid Photon-Atom Entanglement?

Laser light is known to produce "coherent state light," which consists of a superposition of different photon numbers. However, wouldn't the entanglement between the atoms and the light ...
Steven Sagona's user avatar
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Relativistic case recoil of the target by emission of a photon

Generally, text books cover the recoil of a target after absorption of a photon. What happens when a target, it might be an atom, recoil after emission of a photon? The scientific literature shows a ...
Ennio's user avatar
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How do we know that the Sun is 71% Hydrogen by mass from emission/absorption spectra?

In my Intro to Astronomy ("intro" is very important, please keep responses as simple as possible) course, we're currently learning about light and electron orbitals and such, and I came ...
Sami Hanna's user avatar
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Decay rates, time-energy uncertainty, and photon spectrum in two-level system

This question concerns mainly a few statements from the following article https://journals.aps.org/pra/abstract/10.1103/PhysRevA.94.063839. It states: "Early studies of two-level quantum systems ...
AlienTek's user avatar
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Efficiency of light collection of a lens

I am trying to calculate the theoretical imaging performance of a scintillator & camera combination, (scintillator is a plane that emits optical light under X-ray exposure). My question is I found ...
bbbeenn32's user avatar
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What do we actually mean by carrier lifetime in perovskite materials and where do charge carrier reside during that time?

During time-resolved photoluminescence studies in perovskite materials, one sometimes says that it has a microsecond carrier lifetime. What do we actually mean by that? Where does the excited electron ...
Balpartap Singh's user avatar
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Is it possible to make a dual-mode, multi-band laser?

Understanding how N2 and CO2 gas lasers work, Is it possible to make a gas laser (i.e. with the right gas mix and excitation source) that: has more than one mode of operation, emits light in more ...
Hunting.Targ's user avatar
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Can the band gap of quantum dots (QDs) be determined just by knowing the Bohr radius and the size of the QDs?

After extensive research, I've discovered that accurately determining the emission wavelength of quantum dots (QDs) requires understanding several key factors. As highlighted in the book "...
BME2023's user avatar
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Finding the voltage at which saturation current is achieved

In the photoelectric effect, while studying saturation current, I saw that in most graphs with voltage, this saturation current is achieved relatively early at a certain "threshold" voltage ...
Cognoscenti's user avatar
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Are intensity vs wavelength graphs really continuous? [duplicate]

For hot bodies we generally draw graph between intensity and wavelength similar to one in picture. My question is this graph really continous? If it is continuous, does it not mean there are infinte ...
bdogwjumiz's user avatar
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1 answer
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Splitting single photons

Regarding splitting a photon, I found reference to the splitting of a high energy photon into two lower energy, entangled photons, this within the thread 'Application of splitting a photon into two'. ...
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Formation of emission lines, absorption spectra

If we spectroscopically observe a cloud of hot gas, which is on the whole not very absorbent, and which is not illuminated by a source behind it, we observe emission lines. How does this type of ...
Bml's user avatar
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Stimulated emission of radiation

Laser light is monochromatic, coherent and (in many cases) collimated. Are these properties due to stimulated emission of radiation? Also, is it true that a photon emitted as a result of the ...
Grzegorz Kruk's user avatar
1 vote
2 answers
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Why is the relaxation of coherence rate half the spontaneous emission rate?

Consider a two-level atom of which the lower and upper levels are denoted, respectively, a and b. If spontaneous emission from the upper to the lower level is the only source of relaxation, then the ...
Nicolas Schmid's user avatar
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Blackbody Radiation vs Emission Line spectrum

A perfect blackbody has a predicable emission pattern in terms of both intensity and color, given by Planck´s law. Similarly, elements such as Hydrogen or Helium will emit specific wavelengths when an ...
ErikHall's user avatar
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Can an atom absorb a photon, yet finds its total kinetic energy decreased?

Let's assume an atom consists of the nucleus and electrons as point particles. Take the inertial frame to be that of the fixed laboratory. Its total energy consists of the total kinetic and potential ...
itsme's user avatar
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Why is light emitted by an atom different to the light absorbed? Why do we not see absorbed light?

I’m confused about why we don’t see absorbed light. The way I understand it is if an atom absorbs a photon then the electrons move up to an energy level corresponding to the energy of the photon. The ...
lemonmeringue 's user avatar
3 votes
0 answers
22 views

Does the flame-type influence emission spectra?

I am thinking about the following question: when I look at the atomic emission spectrum of a specific element and I am only interested in the visible section of this spectrum and the method of ...
Kevin008's user avatar
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105 views

How is the intensity interpretation of Bohr's correspondence principle equivalent to the frequency interpretation?

The frequency interpretation of Bohr's correspondence principle seems obvious, given that a photon emitted after a dexcitation of an electron has to have the frequency that corresponds to the ...
XXb8's user avatar
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2 answers
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What is the interplay between radiation and photon creation?

While trying to provide an answer to this question, a question popped into my mind. When a charge accelerates, is there always a photon associated with that radiation, or multiple photons? For ...
Lourenco Entrudo's user avatar
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Correct expression for Ratio of Einstein coefficients for spontaneous and stimulated emission

I've come across two different ratios for Einstein's coefficients for spontaneous and stimulated emission on the internet from multiple sources, and these ratios are not equal. Please help me in ...
Dinesh Katoch's user avatar
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1 answer
217 views

What does recoil kinetic energy of an atom mean?

In the textbook I am reading for class it is talking about the interactions of photons with atoms and how when an atom emits a photon it must have the same and opposite momentum of the emitted photon. ...
Aleyna Koro's user avatar
8 votes
2 answers
800 views

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 ...
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Relationship between Current and Stopping Potential in the photoelectric experiment

Is there a way to form an equation for the graph of Current against Stopping Potential for the photoelectric experiment? If so, how?
john's user avatar
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1 answer
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Why is the second-order correlation function proportional to the population of the excited state?

In this paper (click to open it) A. Beveratos et al., 'Bunching and antibunching from single NV color centers in diamond' the authors write the following equation (page 4, eq. 1.2): Namely, they ...
DrManhattan's user avatar
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3 answers
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Does Bremsstrahlung happen when any of scattering take place (Compton, Rayleigh, Thomson etc.)?

The Bremsstrahlung effect happens when an electron is decelerated by changing its direction typically around a nucleus and then a photon beam is released. We know that when a scattering happens, let's ...
medical physics's user avatar
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3 answers
59 views

Photons: Why not wave only? [duplicate]

It seems that Einstein's 1905 paper "Concerning an Heuristic Point of View Toward the Emission and Transformation of Light" notes the discrete quanta of light energy, an idea that leads to ...
JJJ's user avatar
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How to relate band intensity to line intensity?

Let's define the intensity of an emission line $I(v',J'\rightarrow v'',J'')=N(v',J')A(v',J'\rightarrow v'',J'')$ as the number of photons emitted per unit time per unit volume due to the $(v',J')\...
Newbie's user avatar
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2 answers
120 views

Difference between white and yellow light bulbs

Whats the difference between the white light bulbs and yellowish tinted light bulbs what makes the color yellowish? Do they both emit multiple wavelengths of all the colors or does one of them emit ...
Flora561's user avatar
1 vote
1 answer
49 views

Luminescence vs. X-ray emission

When a target atom is struck by some kind of radiation (for example, a $\text{MeV}$ proton), electrons from lower shells are kicked off and replaced by electrons from higher shells, which in return ...
Jakov's user avatar
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1 answer
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Why can't we see in dark where there is a bulb which was once ONN and now it's OFF, the photons released when bulb was ONN should travel to our eye? [duplicate]

Suppose a boy is in a room with a bulb (no windows and other light sources). Now the boy ON's the bulb and OFFs it such that only one photon is released (hypothetical). Now the bulb is OFF. The photon ...
vivian.ai's user avatar
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2 answers
82 views

Can we ionise a gas with concentrated white light?

I don't yet have the backround to answer this question : Does a visible white light enough dense could partially ionise a gas at macroscopic scale ? What I think knowing : Quantified photon energy can ...
Luwalk's user avatar
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2 votes
1 answer
417 views

How many cavity round trips typically occur inside laser resonators?

Is it possible to estimate the number of cavity round trips occurring inside typical laser resonators, e.g. in a laser diode or a He-Ne laser? Motivation: I've come across a short blog text, where the ...
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How to calculate the resolution of spectrometer at the emission edge of a metal in x-ray emission?

I wonder how I can calculate the resolution of the spectrometer from the Al L2,3 X-ray emission edge, and why this method is used to determine the resolution.
chameleon's user avatar
2 votes
1 answer
347 views

Density of final states in photon absorption/emission by a hydrogen atom

Consider a hydrogen atom in an electromagnetic field. The Hamiltonian is of the form $$\hat{H}=\underbrace{\frac{\hat{p}^2}{2m}+V(r)}_{\text{atom}}+\underbrace{\sum_{\vec{k},\sigma}\hbar cka^{\dagger}...
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3 answers
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Electron absorption of photons at varying energies

I am trying to understand the absorption of different energies/frequencies of light by electrons, and I have a few questions (I am relatively new to quantum mechanics, and may have some fundamental ...
user avatar
1 vote
0 answers
44 views

Material that is one-sided translucent [closed]

Is there a polymer material that is translucent from one side but not from the other side? I want to build some custom push buttons that should appear completely black. Only when they are led by an ...
eztam's user avatar
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3 votes
1 answer
120 views

Can we think of spontaneous emission of a photon from an excited atom as a driven harmonic oscillator problem?

This is a kind of strange question, but I'm wondering, in the context of a fully quantum field theoretic treatment of spontaneous emission, if there is any model or way of calculating the process that ...
Cody Payne's user avatar
2 votes
1 answer
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How is the stimulated emission in lasers initiated?

I know in a 3-level laser system for example, electrons get excited from the ground level to the pump level from which they spontaneously decay quickly to the upper laser level. The upper laser level ...
Soun's user avatar
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2 votes
2 answers
221 views

Why do different metals glow with different colours if all solids have the same emission spectrum?

Why do different metals glow with different colors if all solids have the same emission spectrum? According to my teacher, all solids have the same emission spectrum at the same temperature due to ...
Authentic Melody's user avatar
2 votes
2 answers
289 views

If all matter can emit at all wavelengths, can all matter absorb at all wavelengths too?

Based on Planck’s law all matter can emit at all wavelengths at different intensities dependent of temperature. I was wondering if this holds true, does all matter absorb all wavelengths too, at ...
Authentic Melody's user avatar
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1 answer
50 views

Do gases emit radiation at all wavelength? [duplicate]

According to Planck's law, all matter emits radiation at all wavelengths but is this statement true for gases and pure elements? Gases like hydrogen and helium have specific emission spectrums and I ...
Authentic Melody's user avatar
2 votes
1 answer
91 views

Do all matter emits radiation at all wavelengths? [duplicate]

Does all matter emit radiation at all wavelengths? Do gasses also emit radiation at all wavelengths since they have a specific emission spectrum? Shouldn't they only emit radiation according to their ...
Authentic Melody's user avatar
6 votes
1 answer
684 views

Is the Sun considered to be a black body as a whole or it is only the photosphere which is a black body?

I am having some difficulties understating how fusion inside the Sun is connected to the Sun being a blackbody. How do the photons transfer to the photosphere? Is the amount of transferred energy less ...
Authentic Melody's user avatar
4 votes
1 answer
114 views

What are the absorption and emission spectra of $\rm H^+$ ion (a proton)?

Does $\rm H^+$ even produce emission spectrum without an electron?
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