Emission Definition and 567 Threads

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.

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  1. N

    Textbook tries to argue stimulated emission from boson behaviour?

    Hello, "Quantum Mechanics" by Basdevant and Dalibard tries to qualitatively deduce stimulated emission of atoms shined upon with some light by using Bose Einstein statistics. Imagine a certain photon in eigenstate n and if we turn on a potential v temporarily, the chance of it ending up in...
  2. B

    Percent change in thermionic emission

    % change in thermionic emission Q1. Determine the % change in thermionic emission for an oxide-coated filament of work function of 1.3eV if the temperature is decreased by 1.00% at a temperature of 2300K I'm uncertain but i used dJ/J=dT/T ( 2 + ((1160x1.3)/1000) to get a 15% change in...
  3. C

    Standing Waves and Radiation Emission

    In Lewis Epstein’s book Thinking Physics, he says that, since an electron behaves as a standing wave around the nucleus (exhibiting no known position changes, and thus no acceleration and no emission of radiation), something has to push part of the wave into a lower orbit to get the radiation...
  4. R

    How to Determine Temperature and Line Widths in Spectroscopic Observations?

    Homework Statement The spectroscopic observation of an interstellar gas cloud shows emission lines H (λ=6563 A), Hβ λ=4862 A) e OI (λ=1304 A), each one with a gaussian profile of the kind: g(\nu)=A e^[-\frac{(\nu-\nu_0)^2}{2\sigma^2}] Per Hα si osserva σ_{Hα} = 1.2 \times 10^{10} Hz...
  5. lonewolf219

    Stimulated Emission by Laser discussion

    I'm doing a very short presentation on a laser. I want to discuss the most important concepts of a laser (in less than ten minutes). What should I include? I was thinking about stimulated emission and amplification. (But I'm not sure I really grasp these concepts) For instance, does...
  6. L

    Emission or absorption spectrum

    Homework Statement X rays give continuous spectrum and line spectrum. Whether these spectrums are emission or absorption spectrum? Homework Equations The Attempt at a Solution I think it is emission spectrum, because there is no absorbing material. Still, i need confirmation from...
  7. L

    Laser action and stimulated emission

    Homework Statement Revered Members, An electron in ground state makes its way to an excited state upon absorption of photon of energy, equivalent to energy difference between ground state and excited state, and after some time, it decays by emitting the photon and returns to the ground...
  8. K

    Linewidth of emission and the uncertainty principle

    Homework Statement The linewidth of a certain fluorescing dye molecule is 60nm and the peak emission wavelength is 600nm. The lifetime of the dye molecule in the excited state is 1ns. Determine whether the linewidth of the emission is a result of the uncertainty principle. (it may be helpful...
  9. J

    What Are Emission and Absorption in Physics?

    emission and absorption?? confused! hiii, I am just wondering if anybody can give me a very simple definition of each of the two terms, and what the main difference is. Is emission when a wave enters a denser medium (from air to water)? and absorption when a wave enters a medium of lower...
  10. T

    Photomultiplier Tube - Gain and Secondary Emission

    I'm studying about photomultipliers right now, but I'm having troubles understanding the concept of gain and secondary emission ratios... 1) Gain : If I were to take a measurement of the output signal produced by photoeletrons and relate it the the high voltage of the PMT, I'd expect a linear...
  11. L

    Questions about emission spectra and Rhydberg equation for H-atom

    Homework Statement I'm just curious to if I have answered this questions properly, and was wondering if someone can see if I should add more to what I have written, or completely change my answer. I'm pretty confident with what I've answered, but would like someone to check :) So to begin...
  12. T

    How emission theory was disproved by de sitter binary star experiment?

    Actually I was studying on 2nd postulate of special relativity. There I saw Ritz's emission hypotheses says for an object moving directly towards (or away from) the observer at v metres per second, this light would then be expected to still be traveling at (c + v) or (c − v) metres. Now...
  13. L

    Question about Planck's Law and temperature/light emission

    I have a question about Planck's Law. When I first read about it, I misunderstood it to mean that an object at a certain temperature would only emit a very narrow wavelength of light. But as I've looked into it further it appears as though everything in the universe emits a range of light that...
  14. A

    K, L, M electron transitions, x-ray emission lines, conflicting information

    So the basic understanding I have of electron transitions for EDX, XES and other x-ray fluorescence techniques is that a transition from: L to K shell is named K\alpha M to K shell is K\beta N to K shell is K\gamma M to L shell is K\alpha etc. Grand, easy... google leads me to multiple diagrams...
  15. V

    Calculating the energy loss due to sound emission on collision

    Homework Statement I am writing my Extended Essay for IB, where I look at the possibility of obtaining accurate results in open system of a school, by accounting for all energy losses that occur during the investigation. Before conducting my experiments (which included an air track with two...
  16. F

    Understanding Stimulated Emission: Got the what, how about the why?

    I've read the literature on the matter, but I'm still not entirely clear what's going on. The general idea I'm getting is: "You have a photon and an excited atom, photon comes near atom, stuff happens, and now you have two (identical) photons, also identical to the first, and traveling in the...
  17. 0

    Calculating Electric Field Change due to UV Laser Emission

    Homework Statement A very short pulse UV laser is used to liberate a number of electrons from the negative plate in the arrangement in (ii) above(describes parallel plate capacitor system, states plate thickness and separation in vacuum ignore edge effects, charge density and electric field...
  18. 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...
  19. D

    What Are the Rules for Electron Absorption and Emission in Atoms?

    This is my understanding; please, correct me if I'm wrong. If you bombard an atom with em-waves they will never break loose electrons until a certain threshold frequency. At this point the intensity of the light (or the amount of photons) striking the atom is proportional to the number of...
  20. chaszz

    What is electron emission or absorption of a photon?

    What is meant when it is said that an electron emits or absorbs a photon (leaving aside the aspect of heightened or reduced energy states and orbit changes, which I understand.) ? I see four possibilities: 1. Whether the electron is a particle or a wave or some combination of the two, the...
  21. N

    Heisenberg picture describes emission, Schroedinger picture does not

    Am I right in thinking that the Heisenberg matrix interpretation describes emission, while the Schroedinger interpretation does not?
  22. bcrowell

    First historical experiment disproving Ritz emission theory?

    Ritz proposed in 1908 that SR was wrong, and that the speed of light would depend on the speed of the source according to Galilean addition of velocities, c+v. The review linked to from PF's sticky on the experimental basis of SR has a nice section on this...
  23. R

    Deriving the Claim: \sin^2\theta/r Conservation in Pulsar Gamma-Ray Emission

    When I study the mechanism of gamma-ray emission from pulsars, I got a statement saying that the quantity \sin^2\theta/r is conserved along any dipolar magnetic field line. Does anybody know how to derive this claim? Thanks in advance.
  24. L

    Rate of emission from a black body

    What is the proof that the total rate at which radiation is emitted by a black-body radiator is proportional to the fourth power of the temperature? Does this result come from Planck's radiation law? If yes, how?
  25. E

    Atmospheric Gases - absorption, reflection, and emission of radiation

    I'm going to be very careful to avoid the word "greenhouse" because of the indefinite ban on discussions about climate change - I want to be clear, this isn't a topic about that. Part 1 - some gasses in the atmosphere absorb and emit radiation in the thermal infrared range. Gases like water...
  26. Kawakaze

    Emission line in spectrum of a sun

    Hi guys, this is a homework question, but i didnt think it belonged with the physics questions. I have the spectrum of a star, it has hydrogen gamma and hydrogen beta absorbtion lines, but a very very strong hydrogen alpha emission line. What is the significance of this, I would expect a...
  27. M

    Rate of emission of particulates from a power plant

    Homework Statement What is the rate of emission (kg/h) of particulates from a power plant with a thermal output of 3000MW that burns coal with and ash content of 2%? How much is emitted if an electrostatic precipitator of 95% efficiency is used? if the ash contains 1ppM of mercury, how many...
  28. I

    Hydrogen emission spectrum diagram

    Homework Statement Hydrogen atom with ionisation energy 13.6 eV is found to have an emission spectrum with lines at 1.89 eV, 10.20 eV and 12.09 eV. Draw a labelled diagram to show the energy levels of hydrogen atom by showing the transitions of electrons causing the emission of the lines...
  29. I

    Atoms decay via alpha emission have a half-life of 150 min

    2.3 \cdot 10^{10} atoms decay via alpha emission have a half-life of 150 min. How many alpha particles are emitted between t=30 min and t=160 min? \begin{flalign*} 150 &= \frac{\ln 2}{\lambda}\\ \lambda &= 0.046 \\ \\ K &= K_{0}e^{(-\lambda)(t)}\\ &= (2.3 \cdot 10^{10})e^{(-0.046)(30)}\\...
  30. P

    X-Ray emission and Bragg Scattering (K-Alpha and K-beta absorption)

    Homework Statement Complete this sentence. When doing Bragg scattering of x-rays off of NaCl, the first order K-Alpha peak has an energy that is ___________ the energy of the second order K-Alpha peak. Known Information It is known that the Intensity of the K-Alpha is greater than the K-Beta...
  31. O

    Emission Spectral Lines & the Rydberg Formula

    FIGURED IT OUT, PLEASE DISREGARD Homework Statement Find the shortest wavelength of the Lyman series for a triply-ionized beryllium atom (Be3+). Express your answer in nanometers using four significant digits. Homework Equations Rydberg's Formula: 1/\lambda=RZ2(1/n12 - 1/n22) The Attempt...
  32. B

    Beta Emission and Atom Deflection

    I'm dealing with this problem for an MCAT review: Following beta-emission by a neutral atom at rest, the respective linear momentums of the beta(-) particle and the resulting atom are shown below. (see attachment for message) It wasn't too difficult to see that an extra force is in play, and...
  33. C

    Hydrogen Emission Spectra Wavelength

    Homework Statement A transmission diffraction grating with 528 lines/mm is used to study the line spectrum of the light produced by a hydrogen discharge tube. The grating is 1.3m from the source (behind a hole in the center of a meter stick). An observer sees the first-order red line at a...
  34. daisey

    Plutonium and Neutron Emission

    I have been reading up on radioactivity (Wikipedia). I keep coming across articles which talk about emission of Neutrons (during Plutonium decay, for example). Now I know alpha radiation is basically Helium-4 nuclei, but that consists of both Protons and Neutrons combined in a nucleus. What...
  35. L

    Crystal Emission: Understanding Fundamental and Harmonic Frequencies"

    Say I have a 25MHz Crystal that's connected to a Microprocessor/Microcontroller or spread spectrum clock generator. Does the crystal emit Electromagnetic radiation at its fundamental frequency or it's harmonic frequencies? I keep hearing - " I see a peak at ~50MHz, it must be the 2nd harmonic...
  36. 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...
  37. A

    In stimulated emission how does the incident photon make release of

    In stimulated emission how does the incident photon make release of other photon from another atom? advanced thanks.
  38. S

    Is There an Equation to Determine Gamma Ray Frequency from Radioactive Decay?

    Readers, Hi, I'm new here, and have a question that has piqued my interest, and have not found a solution elsewhere. My question is as such: is there an equation to determine the energy or frequency of the gamma ray emitted as a byproduct of radioactive decay for a given isotope...
  39. nukeman

    Spectra: Where do the emission lines come from?

    Im just trying to figure something out here. Iv been working on some spectra stuff. Now, when I look at a gas, I see the spectra, but if I turn up the intesnsity, new lines appear? Where do these lines come from, as I am looking at the same game, just turned up intensity?
  40. 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...
  41. M

    Angular diameter of neutrino emission

    Homework Statement If the Superkamiokande neutrino detector could accurately determine the direction of detected neutrinos, what would the angular diameter, in arcminutes, be of the neutrino emission as seen from Earth. Assume all the neutrinos are ^{8}B neutrinos with energies <14.02MeV...
  42. AlexChandler

    Radiation Emission and Absorption

    Homework Statement A sphere of radius 0.500 m, temperature 27.0°C, and emissivity 0.850 is located in an environment of temperature 77.0°C. At what rate does the sphere (a) emit and (b) absorb thermal radiation? (c) What is the sphere's net rate of energy exchange?Homework Equations...
  43. A

    Why Gamma Ray Emission Has No Change in A or Z?

    Why in gamma ray emission there is no change in A or Z ? We know that in Alpha decay 2 protons and 2 neutrons are subtracted from the element. and in Beta decay there is change in atomic number by + or - 1. but why there is no any change in Gamma Decay in mass number A or atomic number. i...
  44. H

    How Many Photons Hit Your Retina from a Distant Light Source?

    Homework Statement A light bulb 10km away from you emits visible photons at a rate of 3x1018 photons/s. Assuming this is the only source of light (the whole place is dark), and your dark-adjusted retina has a diameter of 7mm, then how many photons/s hits your retina? Homework Equations...
  45. P

    Emission current from hot cathode in an X-ray sourse

    Part of an experiment involved measuring the intensity of an X-ray beam through a piece of aluminium as a function of emission current of the X-ray source. I originally fitted a linear fit to my data (although it does start to level off at high emission currents). The marker however said that it...
  46. L

    Absorbtion,reflection,and emission.

    I want to see if I understand these rules correctly. Us humans emit mainly in the infrared, that can be described by wiens law, but when visible radiation falls upon us, our body absorbs some part of the white light, but reflects whatever it doesn't. Smurf's for example reflect the blue part of...
  47. N

    Single Photon Emission: Examining the Evidence

    On the web are some informed-sounding discussions saying that the various videos showing the appearance of the dots on the photo-sensitive surfaces can by no means guarantee that only one photon got through. A lot hinges on that, thanks for referring me to other posts which show certainty of a...
  48. A

    Can you explain the phenomenon of stimulated emission in lasers?

    I am interested in learning the nature of the interaction between a photon and the atoms in a medium that has undergone population inversion that causes stimulated emission i.e. if an excited-state atom is perturbed by a photon (with an electric field of specific frequency), why does it emit an...
  49. E

    Ray Type of Bulb Light Emission

    what type of ray does the bulb light emit?
  50. T

    How Does a Slab Reach Thermal Equilibrium When Exposed to Blackbody Radiation?

    Consider a slab of matter contained within two infinite planes a distance of s = 1m apart. absorption coefficent =1m2kg-1 density of slab 1kgm-3 heat capacity 103^3jk-1kg-1 assume the absorption coefficient to be independent of wave length 1.Suppose one face of a slab is illuminated...
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