What is Emission: Definition and 566 Discussions

The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state. The photon energy of the emitted photon is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify elements in matter of unknown composition. Similarly, the emission spectra of molecules can be used in chemical analysis of substances.

View More On Wikipedia.org
Recent contents Top users
  1. 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.
  2. afcsimoes

    Trigger the emission of light by an atomic electron

    What does trigger the phenomenon of an atomic electron losing energy through the issue of a photon? (I know how an atomic electron absorbs light and changes to a more energetic level but I never read an explanation cause-effect of the inverse)
  3. Maximtopsecret

    Emission of a moving particle

    Homework Statement Electron e, mass m, moves in constant homogeneous magnetic field H. Find time interval for electron's energy to decrease 10 times due to emission. Homework Equations I know for sure from the class that m*a=(e/c)*(v⊥)*H (Lorentz force); intensity -I=dE/dt=-2e4v⊥2H2/(3m2c5)...
  4. P

    Electron's emission in Sn atom

    Good morning everybody, here's a problem about excitations energy of the core level of a Sn atom. It says to construct the scheme of the core levels of Sn indicating the excitations energies. Now the K edge (the problem doesn't say we are necessarily talking about X-rays, but I think we are...
  5. 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...
  6. G

    Solving the Mystery of Spontaneous Emission

    By Spontaneous emission it is said that the electron jumps to the higher energy state and then after some time "spontaneously" falls to the lower state. It is still not clear to me, what makes the electron to "fall" back to the lower state, if higher state is also allowed state and excitation...
  7. D

    How can we explain continuous absorption / emission?

    I am familiar with the explanations for atomic absorption and emission line spectra and how the existence of discrete, fixed energy levels can give rise to the absorption/emission lines that are seen at only very particular frequencies of EM radiation. However, I have no intuitive understanding...
  8. Z

    Stimulated Emission = Stimulated Absorption

    I'm having a bit of trouble understanding this. I am going through the section in Griffith's regarding Einstein's Coefficients. For a system in equilibrium, the rate of particles undergoing emission needs to equal the rate of particles undergoing absorption in order to maintain equilibrium...
  9. A

    Understanding Real-World Emission Spectra: Are Solids Similar to Blackbodies?

    Hi all, I've got two questions about the emissions spectrum from solids. Question #1: I feel like I have a reasonable understanding of line absorption and emission spectrum of low density gases based on transitions of electrons between discrete allowed energy levels in a gas. I'm trying to...
  10. 3

    A heated cathode inducing thermionic emission of electrons.

    Hello all. I have been looking at this problem: I wrote three equations there, one for each part, which I think will help me solve each part; is my approach to the problem using those equations that you see there correct? I am just looking for some advice on where and how to start this problem...
  11. 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?
  12. K

    Spontaneous emission entropy

    Does entropy increase during spontaneous emission? If not, how is the information about the emitted photon mode encoded into the initial state of the atom (and/or environment)? If so, where does the extra information come from?
  13. 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?
  14. H

    Emission radiance in participating media

    This link discusses radiation in participating media. Eq. 9.13 gives a prediction of the changing power of a ray along the path length as: I_\eta(x)=I_\eta(0)\exp(-\tau_\eta)+I_{b\eta}[1-\exp(-\tau_\eta)] where \tau_\eta is the absorption coefficient times the length. So, the first term...
  15. W

    How does stimulated emission occur in lasers?

    I was reading about LASER production when I came by the concept of stimulated emission. The book I was reading doesn't elaborate the topic much,so far I have understood what stimulated emission is but not how it happens. When a photon strikes an excited atom the atom falls to it's ground state...
  16. H

    What is the percentage of Cs137 decays that result in a gamma ray emission?

    So I have a problem where I'm given the decay rate of a sample which contains Cs137, 10 mCi, and I'm basically given the percentage of radiation detected by the detector. But the wording of the question is: "What count rate would be observed in a perfectly efficient gamma detector" Sounds to...
  17. 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: ##...
  18. 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...
  19. A

    Broadening of emission peak - "red/blue spike"

    As I understand, spectral emission peak can broaden due to high temperature of the emitter. For example, emission of "cold" CO2 will have a thin peak at 4.3um while the CO2 emitted from a (very hot) rocket plume will have a broad emission at ~4um - 4.7um (called "red/blue spike") What is the...
  20. Teemo

    Radioactive Decay to a Non-radioactive Isotope

    Homework Statement Magnesium (Z = 12) has isotopes that range from Mg–20 to Mg–31. Only Mg–24, Mg–25, and Mg–26 are not radioactive. What mode of radioactive decay would convert Mg–20, Mg–21, Mg–22, and Mg–23 into stable isotopes most quickly? (A) electron emission (B) alpha particle emission...
  21. J

    Electromagnetic emission lines for a hydrogen atom

    Homework Statement Hi, I've been unable to find a relevant thread for a question that I've been stuck on for a couple of days now. Here it is; One of the electromagnetic emission lines for a hydrogen atom has wavelength 389nm. Assiming that this is a line from one of the Lyman (nf =1 )...
  22. PWiz

    Why does photoelectric emission not depend on intensity?

    I understand that intensity is power per unit time and that ##I = 2π^2f^2x^2_oρv## for regular waves (I don't know if the formula applies to E.M. waves or not). What I don't understand is why electrons are only released when the electromagnetic radiation incident on the metal surface is beyond...
  23. G

    Biophoton Emission Outside Visible Range

    There are a lot of florescent proteins in the visible range, but why haven't we fount any above or below that range? I think a protein that emits radio waves could be very helpful both biologically and scientifically. Are we not looking for such proteins, or do they not exist?
  24. G

    Molecules With Radio Emission Under Current

    I am working on a project, however I am having trouble finding the right material for it to work. I am looking for a nano-material or any molecule that will emit a radio frequency when subjected to a voltage or a current at around 37 degrees Celsius. I would really appreciate it if someone could...
  25. H

    Blackbody emission in 2D coordinates

    The spectral radiance of a blackbody has units of W·sr-1·m-2·Hz-1. How do I deal with these units if I want to think about a 2D problem of radiation in Cartesian coordinates? I assume that instead of a sphere of emission (which would result in artificial decrease in intensity with the inverse...
  26. L

    Dark body vs light body and heat emission

    So, I've had several people insist that a dark colored object will radiate heat faster than an identical light colored body. I do not believe this is the case. We know that dark bodies ABSORB more short wave than light colors, and thus become hotter as a result...but that's not the issue...
  27. S

    Light emission and energy of states

    Homework Statement The emission spectrum of thermally excited sodium atoms practically consists of a single intensive line at 589 nm wavelength. What is the energy difference (in eV units) between the excited and ground states of the sodium atom? Homework Equations E = hc/lambda, we also know...
  28. X

    Calculating Average Emission Wavelength from Spectral Intensity Chart

    I haven't had calculus in over 2 years and so I am not exactly sure how to go about this. I am inclined to believe some form of integration would be needed. I took the chart below from a paper on LED wavelength emission. The authors say that the vertical line represents the average emission...
  29. 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
  30. A

    Alpha Particle Emission & Neutron Imbalance

    Alpha particle emits when no. of neutrons in an atom are much more... My ques. Is that the no. Of protons and neutrons emitted are same so the substance formed after the reaction should still have much more neutrons than protons.. Infact mathematically the ratio increases.
  31. U

    What Transitions Create Calcium's Emission Lines at These Wavelengths?

    Homework Statement Strong emission lines from calcium were observed at ##422.7nm##, ##610.3nm##, ##612.3nm##, ##616.3nm##, ##1034.9nm##, from transitions between ##4s^2##, ##4s5s## and ##4s4p##. The transition of ##422.7nm## was also observed at absorption. The singlet-triplet splitting of...
  32. Shailesh Pincha

    Stimulated Emission: De-exciting Electrons with Photons

    How is a photon responsible for de-excitation of an electron in higher energy state?
  33. S

    Probable electron field emission switch

    Hi again , i did some reading about this topic on google and there were only a few articles about it , so I would like to ask you for some advice.I ask this from a previous thread i asked about electrons in vacuum...
  34. H

    Ionizing Radiation and Electron Emission

    Can someone clarify what Ionizing Radiation is and how it relates to Alpha, Beta, and Gamma Emission and/or Absorption? A question in the Princeton Review Science Workbook read: The daughter nucleus of CS-137 is:... and the answer is 137 - Barium. The text says that Alpha, Beta, and Gamma...
  35. D

    Identify emission line spectrum

    Homework Statement refer to the question Homework EquationsThe Attempt at a Solution from figure b , moving to the right, we know that the wavelength increases. since e= hc/λ , so the energy diffrenece should be increases as going to the right, so i consider line 1,2 and 3 is in a specific...
  36. Q

    Problems of Spontaneous Emission, thanks.

    How to change the upper step to lower step on the figure? Why does N2(0) change to N2(t) the exp(-t/21) will be missed? Thanks.
  37. D

    Why Does Metal Require More Energy for Electron Emission?

    Homework Statement in my book , i was told that for the emission of electron from a metal surface to occur , the photon which incident on the metal must have at least the energy more than the work function of metal , whereas for the emission of electron from H atom, the photon must have exactly...
  38. 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?
  39. R

    Emission Spectrum: Color Lines & Atomic Orbital Band

    Are each of the color lines in the emission spectrum correspondant with a single band in the atomic orbital? For example if an electron rises to the 3p band it will emit one line of color only.
  40. R

    Back to basics: What exactly is an emission spectrum?

    This will probably end up being a stupid question with a simple answer, but if you don't ask and just accept things then where's the understanding? Anyway, the spectrum of emission is usually shown as some form of Intensity vs Wavelength, my question is how does it relate to time and how is it...
  41. Y

    What causes stimulated emission to occur in quantum mechanics?

    I have been learning some introductory quantum mechanics and stimulated Emission is giving me some problems conceptually. I understand that photons can be absorbed to bump electrons up to higher energy levels and that electrons in the higher energy state spontaneously decay back to the lower...
  42. 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...
  43. 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...
  44. R

    Can a plasma give off black body emission?

    This may seem like a strange question, I'm trying to differentiate between the spectra from a plasma and the spectra from a black body, is there a difference? I'm thinking the spectrum from a plasma would be that of bremstrahhlung as it is ions flying everywhere, so it would not be possible...
  45. DennisN

    Unidentified emission line in Galaxy Clusters

    I could not find a thread about this (and I hope I don't start a duplicate one :smile:). I got a mail from a friend today about this: Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith...
  46. kelvin490

    Radiation emission and absorption

    Any object can emit and absorb radiation and the power of emission can be represented by the Stefan-Boltzmann law: P=AεσT4 In many texts the net power radiated is the difference between the power emitted and the power absorbed: Pnet=Aεσ(T4-Ts4) where Ts is the temperature of surrounding...
  47. I

    Laser Plasma Emission: Mechanisms Explained

    what are the different mechanisms that cause plasma emission?
  48. 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...
  49. H

    How can I optimize heat emission from underfloor heating pipes?

    Hello! It has been years since I had physics at uni, and I have forgotten lots of it, so I need some help here. The issue concerns the underfloor heating pipes and how to reduce loss. Most conventional systems use insulation boards to slow down heat conduction towards the floor. Some...
  50. L

    Direction of Photo Electron Emission

    I was looking for information on how the photo electrons are emitted when under X-ray radiation. In this ancient review paper here http://journals.aps.org/pr/pdf/10.1103/PhysRev.30.488 they state that the most common angles for non polarized X-ray beams (of various energies) range roughly at...
Back
Top