What is Photon emission: Definition and 69 Discussions

Time-resolved photon emission (TRPE) is used to measure timing waveforms on semiconductor devices. TRPE measurements are performed on the back side of the semiconductor device. The substrate of the device-under-test (DUT) must first be thinned mechanically. The device is mounted on a movable X-Y stage in an enclosure which shields it from all sources of light. The DUT is connected to an active electrical stimulus. The stimulus pattern is continuously looped and a trigger signal is sent to the TRPE instrument in order to tell it when the pattern repeats. A TRPE prober operates in a manner similar to a sampling oscilloscope, and is used to perform semiconductor failure analysis.

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  1. lambdadandbda

    How Does Special Relativity Affect Photon Emission Angles?

    I'm doing special relativity in undergrad and I have the following problem: Let a particle of mass M travelling at speed ##\beta = 1/2## (##\gamma = 2/\sqrt 3 \ \ c=1##) decay in to two photons: ##A \rightarrow 1+2## 1) Calculate energy and moment of the photons in the reference frame of the...
  2. T

    I Fourier Transform of Photon Emission Hamiltonian

    Hey all, I just wanted to double check my logic behind getting the Fourier Transform of the following Hamiltonian: $$H(x) = \frac{ie\hbar}{mc}A(x)\cdot\nabla_{x}$$ where $$A(x) = \sqrt{\frac{2\pi\hbar c^2}{\omega L^3}}\left(a_{p}\epsilon_{p} e^{i(p\cdot x)} + a_{p}^{\dagger}\epsilon_{p}...
  3. sol47739

    I Do atoms recoil when emitting a photon?

    Hello! I have some questions regarding the photon emission and whether the atom recoils or not. When an electron in an atom emits a photon. One can calculate the energy of the photon by the difference between the energy levels from where it left to which it returned. Let’s say it jumped from...
  4. Mr Fallspring

    I Double-Slit Experiment: Does rate of photon emission matter?

    Hi there! High school physics teacher hoping to pick the brains of people who know more than I do here. I'm curious whether the rate of photon emission has any noticeable effect on the diffraction pattern generated by the double-slit experiment. To be clear: I understand a diffraction pattern...
  5. J

    A The Probability Distribution of a Bosonic Field when Emitted

    If a bosonic field is probabalistic, and if it can be emitted (suddenly coming into existence), what determines its probability distribution when it is emitted from a fermion? In other words, one thinks (or at least I think) of a fermion field as already being in existence and already having...
  6. S

    I Can there be some kind of photon emission caused by space expansion?

    Are there any kind of observed and experimentally verified processes or mechanisms where photon emission occurs and which are directly cause by spacetime expansion in some way?
  7. sol47739

    A Cause of spontaneous emission?

    I am reading this chapter 3 from the book called The Quantum Vacuum by P.Milonni.(Attached in the pdf, look at chapter 3.2 Spontaneous emission)There they say that spontaneous emission is due to both quantum fluctuations and radiation reaction. They say the transitions induced by the quantum...
  8. F

    De-excitation of a moving atom with photon emission

    The information I have are the following: ##p^\mu=(E, p, 0, 0)## ##p'^\mu=(E', p'\cos\beta, -p'\sin\beta,0)## ##k^\mu=\tilde{E}(1, \cos\alpha, \sin\alpha, 0)## Where: ##E=\sqrt{M^2+p^2}## ##E'=\sqrt{m^2+p'^2}## Using the conservation of the four-momentum ##p^\mu=p'^\mu+k^\mu##...
  9. R

    I How does this experimental result show photon emission?

    First I'll explain my understanding, because I'm not very confident in it. The main point is that the electrons are ejected and then accelerated to a very high kinetic energy. Then they start smashing into the anode. Most will go through a series of collisions before completely stopping, so that...
  10. M

    B Redshifted Photon Emission vs Transport: Magnitude of Gravitational Redshift

    I am considering the magnitude of the gravitational redshift and I look at the process of a photon leaving an atom from the Sun. I am asking whether the processes in the atom, viewed as a clock, would lead us to conclude that the emitted photon, at the time of emission, would itself be...
  11. F

    Electron-positron annihilation, photon emission angle

    I consider the laboratory system. The four momentums in this reference system are respectively: ##p^\mu = \big(\sqrt{|p|^2+m^2}, 0, 0, |p| \big)## ##p'^\mu= \big(m, 0, 0, 0 \big)## ##k^\mu = E\big(1, 0, 1, 0\big)## ##k'^\mu = E'\big(1, 0, -\sin \varphi, \cos \varphi \big)## I used conservation...
  12. M

    Photon emission in electronic transitions

    How would you explain, on a basic level, why only one photon (as opposed to two, three...) is emitted when an electron in an atom changes its energy level? This is for students with only introductory Physics background.
  13. LordWhiplash

    I Why is the lowest energy level close to the center?

    While studying photon emission, I noticed that I never really understood why the higher energy level is farther from the center of the atom. To me it seems counterintuitive, because usually the forces of attraction are greater at shorter distances, which would imply a higher energy consumption...
  14. F

    I QED & In-Ground Electrons: Why No Photon Emission?

    In ground state electron does not emit photon.Can we use QED to explain why in ground state electron does not emit any photons?
  15. S

    I How Would Electron Entanglement Affect Photon Emission

    Suppose you have a pair of electrons in the same quantum state, and are thus spin entangled, and they absorb a pair of photons and release them at the same time. How would this affect the photons? Would the photons be entangled? Would it affect the photon spin, and if so, how would it affect the...
  16. Jim Fern

    Energy lost through photon emission

    Hey guys, new here. Here is my first question for the forums: Let's say that I have a controlled environment for an experiment whereby I want to heat, say, one cubic centimeter of steel until it is white hot. Assuming that I have perfect containment set up for it such that no energy can be...
  17. A

    I Photon emission, power output (and black holes)

    I recently re-read an article by Muller (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time, and the possibility of time reversal given sufficient energy dissipation (basically during black hole evaporation, he concludes). Although the paper is on arXiv and not peer reviewed, Muller...
  18. R

    I Compton effect: how can it take place?

    English is not my native language. So, I hope to be understood. :-) The Compton effect is the dynamics in which high-energy incident photons (X or gamma) are scattered by electrons of certain materials, like graphite. The electrons are supposed to be free, as they are only weakly bounded by...
  19. A

    I Change in electron energy level and photon emission....

    Hi all, This is likely a naive question, following up on something @vanhees71 posted some time ago in another thread: My question is the following - if we take an electron that has, for example, absorbed a photon, is the portion of the wavefunction representing the electron in a lower energy...
  20. J

    A Accelerating particle photon emission mechanics?

    It's been a while. But I have always received the help I needed on this forum. I had this question in my head, When a particle accelerates, it creates an oscillating electric field, and a photon. How much does this effect, affect the energy of the particle itself? Say I had a particle...
  21. M

    I Probability of one-photon loss from a cavity

    Why is the probability of one-photon loss from a cavity in the time interval ##[t, t+\delta t]## is: ##\kappa \delta t\langle \psi(t)| \hat{a}^{\dagger}\hat{a} |\psi(t)\rangle## where ##\kappa## is the decay rate. It looks like the Fermi Golden rule but it's not exactly it.
  22. S

    A Probability of photon emission from quantum dot

    Hi guys, I am looking for a formula which I am sure exits but I cannot locate it. The problem is that a quantum dot absorbs a photon of wavelength λ0(dot is semiconductor or could be any other material). Assuming that it reemits a photon, what is the probability that this emitted photon will...
  23. M

    I Hydrogen Atom Photon Emission Wavelength Formula

    I am trying to calculate the Lyman-alpha wavelengths of photons emitted from different hydrogen-like atoms such as deuterium and positive helium ion 4He+, using the relation 1/λ = R*|1/ni^2 - 1/nf^2|, where R is the Rydberg constant and ni and nf are integer numbers corresponding to the initial...
  24. H

    Does an electron beam bending lose energy by photon emission

    A beam of electron in vacuum with velocity v enter a region of spa e with a electric field E. The field is such the electrons circle with radius r. The electrons are now accelerating at constant tangential speed. Because this is not an atomic orbital then by classical physics the electrons...
  25. W

    Power and rate of photon emission with a given temperature

    Assuming that your surface temperature is 99.1 F and that you are an ideal blackbody radiator (you are close), find (a) the wavelength at which your spectral radiancy is maximum,(b) the power at which you emit thermal radiation in a wavelength range of 1.0 nm at that wavelength, from a surface...
  26. D

    Measuring Electron Recoil from Photon Emission: Experiments & Methods

    Has electron recoil due to photon emission ever been confirmed by experiment? cause I can't find any reference to electron recoil being measured anywhere I look. If it has been measured, what methods do they use?
  27. D

    Photon emission from dipole antenna

    Are photons emitted from the stationary protons in a dipole antenna? The protons don't accelerate at any point but their electric field does contribute to the electromagnetic wave.
  28. D

    Understanding Recoil in Photon Emission and the Role of Quantum Electrodynamics

    This is the second time I've asked this question, I thought I'd add some extra details. Consider a single accelerating electron, this electron emits a single photon wave which radiates out spherically in a superposition, What direction and what time does the electron recoil if there is no...
  29. D

    Electron recoil due to photon emission

    Consider a single accelerating electron, this electron emits a single photon wave which radiates out spherically in a superposition, What direction does the electron recoil if there is no defined direction for the photon?
  30. D

    Relativity and Photon Emission

    Consider another situation where electron A accelerates past stationary electron B. However. from the perspective of electron A, Electron B appears to be accelerating, does this mean that A could absorb a photon from electron B?
  31. S

    Photon Emission and Energy Levels

    Hello, I was trying to solve a problem in my course book, and I noticed I don't really understand energy levels completely. My ignorance covers more than one specific problem, so I figured I'd ask a general question, rather than post the problem. The Rydberg formula: ##...
  32. 1

    Angle of photon emission from particle decay (Particle Phys)

    Homework Statement a) Particle A decays at rest into two photons. Calculate, in terms of the rest mass of A, the energy and momentum of each photon. b) In a different reference frame, particle A is initially in motion such that its kinetic energy is equal to its rest energy. Find the momentum...
  33. LaserMind

    Is the electromagnetic field more or less real than the quantum wavefunction?

    When a photon is at a large distance fom it's starting position then the wave is spread-out laterally. How can a wavefront for one photon collapse instantly over a massive surface area?
  34. S

    Action corresponding to photon emission

    Hi I am trying to write the probability of photon emission due to transition of electron in feynman's path integral formulation. I am stuck trying to figure out the action corresponding to the photon emission. Would anyone shed some light on this? Thanks
  35. M

    Electron Transition & Photon Emission in Hydrogen Atom

    How an electron transition from lower energy state to higher energy state in hydrogen atom emits a photon?
  36. M

    Photon emission during x-Ray ionization process

    Dear mates: During ionization with radiant energy there is a photon emission (see http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html). I know photon emission occurs by a decay of radiant energy from a excited state and what is confusing to me (I can't find a logical conection) is that...
  37. J

    Electron energy states and photon emission?

    Are lower energy electron orbitals always closer to nucleus than higher energy orbitals? Is this energy proportional to the inverse square law and Coulomb's law? When an electron jumps down to a lower energy orbital, is potential energy not just converted to kinetic energy, and so where does...
  38. E

    Photon Emission: Purcell's Textbook Presentation

    A textbook presentation is given by Purcell: "Electricity and Magnetism", Appendix B, "Radiation by an Accelerated Charge". He carefully shows how the changes in the Coulomb field of a quickly decelerated electron propagate outward with velocity c. Since the field was moving past the observer...
  39. G

    The classical free electron photon emission and absorption.

    The definition of the Gaunt factor. Hello. I'm wondering about the Gaunt factor. I'm currently interesting in the spectroscopy in which the Gaunt factor is the correction factor to the classical cross section associated to the photon with electron thus the corrected formula is the identical...
  40. I

    Mechanism behind photon absorption and photon emission

    hi all, i learned that only certain orbits were allowed in the atom and that if the electrons occupied any of the orbits in between, that they would no longer be in a resonance orbit (i was taught that the allowed orbits were the electron probability wave in resonance and therefore no EM...
  41. R

    Photon emission by an excited hydrogen atom

    Typically (in popular literature) the process of photon emission by an excited atom is considered as an instant event. But actually it is quite likely that it is a continuous process. Such processes are usually described by evolutionary differential equations (ODEs or PDEs). Assume that we...
  42. S

    Wave-Particle Duality: Random Photon Emission

    Hello, I'm studying the wave-particle duality, more specifically the matter-wave function of de Broglie: \Psi(x,t)=A sin 2\pi(\frac{x}{\lambda}-\nu t) where \lambda is the de Broglie wave-length and \nu is the frequency. The interpretation of this wave is that, \Psi^{2} would be the...
  43. D

    Energy of a photon emission or absorbtion

    Homework Statement When energy is absorbed is the E value negative and when the energy is emitted is the E value positive? Homework Equations E=hf=E1-E2 (Is this equation correct for noth emision and absorbtion or just absorbtionbecause this is what my textbook says) E=-13.6/n^2...
  44. X

    Photon Emission from electrons and the EM field

    Ok, I've been reading up on the EM field and how it exerts force on charged particles. By exerting this force it creates 'ripples' in the EM field and this is felt by other charged particles as a force (either of attraction or repulsion). We say that the two particles exchanged a virtual photon...
  45. A

    How Do Black Holes Emit Photons?

    Hi, I've been reading through Stephen Hawking's 'A Brief History of Time' and I have reached a section about how, contrary to popular belief, Black Hole's are not necessarily black since they emit photons outside the event horizon. I am wondering how they emit photons. Does it have to do...
  46. O

    Bohr Model and photon emission

    I am feeling a little stupid asking this considering I am about to graduate with my BS in chemistry. But I have never given this much thought, nor do I remember learning this and I can't figure out a proper explanation. I am sure I am overlooking a simple detail, but I can not figure it out...
  47. C

    Is photon emission possible without electrons changing energy levels?

    Does molecular vibrational transition and consequent emission of infrared radiation involve electrons changing energy level? In wikipedia, about vibronic transitions it says "Most processes leading to the absorption and emission of visible light, are due to vibronic transitions. This may be...
  48. C

    Photon Emission & Atom Entanglement: Spin & Beyond

    If a photon is emitted from the nucleus of an atom, and the atom is at rest is the photon and the atom entangled? If their spin angular momentum was zero before the emission. And is it possible to have an atom emit a photon from its nucleus and one of its electrons at the same time, and would...
  49. P

    What Are the Work Function Limits of the Metal in Photon Emission?

    Homework Statement hypothetical one electron searsium element. n=-20eV, n2=-10eV, n3=-5eV, n4=-2eV. photon emission n3>n2 and n3>n1 will eject photoelectrons from unkown metal, but photon emitted from n4>n3 will not. what are the limits (max and min values) of work function of the metal...
  50. V

    Photon Emission: Atom Collapse & Radial Forces Explained

    I'm sure I've heard the explanation for this before in class but I can't quite remember it: If electrons of an atom emit photons (ie lose energy), the orbits of the electrons will become smaller, right? If so, wouldn't the atom eventually collapse? What radially outward force keeps the...