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. M

    Understanding Atomic Dipoles and Spontaneous Emission

    Hi, In quantum optics, the interaction between light and atoms is described by a Hamiltonian of the form d.E where d is the dipole moment of the atom. The picture given is basically that this is a vector and we take the the dot product with this and the electric field vector (whose direction...
  2. M

    How does an EM wave affect an atom's energy levels?

    How can an incident photon cause an atom to de excite??
  3. A

    How Does Hawking Radiation Affect Black Hole Temperature?

    Hi, I recently came across this formula: T = \frac{\hbar c^3}{8 \pi GK_BM} As I understand it deals with the radiation that is believed to be emitted by a black hole. Does it describe the temperature of the radiation? Thanks
  4. A

    Question re: Deuterium Emission Spectrum

    Deuterium Spectrum (nm) 410.07, 433.93, 486.01, 656.11 I came upon these figures on a commercial product site for Deuterium lamps. So, question: Are they correct? If so, then... 364.5068222*(3^2/(3^2 - 4)) = 656.11 364.5068222*(4^2/(4^2 - 4)) = 486.01 364.5068222*(5^2/(5^2 - 4)) = 433.93...
  5. N

    Emission of a Photon: Origin and Role of Electron Constituents

    When an electron jumps to a low energy level, it emits a photon. 1. Where does this photon come from? 2. Do the constituents of an electron have any role to play in this emission?
  6. DaTario

    Light scattering and thermal emission of a body

    hi All, We know from QM that black bodies at temperature T emits light in a well stabilished patern. Now what if the body has color? Which is the emission patern of a green snooker ball for example, at temperature T? When scattering white light we see this ball green because it absorbs...
  7. H

    Blackbody emission and absorption

    I am trying to understand radiative transport of thermal energy in materials from first (or close to first) principles. I do not understand the systematics/statistics of how photons are emitted and absorbed in a medium. How is it that photons can be emitted at so many wavelengths and atoms can...
  8. C

    Can an electron emit a single photon without violating conservation laws?

    Someone told me that an electron can't emit a single photon because it would violate conservation of momentum and energy. I thought about cyclotron radiation. Let's say an electron is being bent in a B field so it starts to radiate, can't we just say that this momentum and energy came...
  9. C

    Question about light emission.

    In the Aharonov–Bohm effect when charged particles are deflected do they emit light?
  10. S

    What is spin and why does is particle emission possible

    Don't know why i put "does is" in the title...oh well... Hey guys, I'm taking Physics in high school and have always been very interested in things such as quantum physics, black holes and the like, but there are a few things that I've been searching for but can't seem to find a non-technical...
  11. D

    What is the Hydrogen Emission Spectrum for Transitions to the n = 1 Level?

    Homework Statement What wavelengths emitted from a hydrogen gas discharge tube are associated with transitions from higher levels down to the n = 1 level? [a] infrared [b] visible [c] mixture of infrared and visible [d] ultraviolet Homework Equations Equations: 1/λ =...
  12. C

    What do broad and strong emission lines mean and what are the main types of AGN?

    Cosmic greetings, I am reading up on active galaxies, and 'strong' and 'broad' emission lines are mentioned everywhere, yet no definitions given. Do they mean that the object is emitting energy across a large part of the spectrum, or that it's emitting a lot of energy? Also, I am confused...
  13. AntSC

    Optics Problem - Maximum Dipole Emission

    I am stuck with considering a problem. I don't even really know where to start so any pointers would be a great help. I am considering a semi-analytic model for some data i have. The situation is looking at how light propogates from a point source in diamond to air. At the surface of the...
  14. C

    Spontaneous vs Stimulated Emission

    Hi! I wanted to check if I have got the correct interpretation of stimulated vs spontaneous emission. It seems like stimulated emission is defined as a process for which an excited atom/electron spontaneously relaxes down to a lower energy level. Stimulated emission on the other hand...
  15. 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...
  16. 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...
  17. X

    Why Is Carbon-12 Emission from Radium-226 Highly Unlikely?

    Homework Statement Radium 226 usually decays via three consecutive alpha decays into Pb 214. Show that energetically possibly for radium 226 to decay into 214|86 Pb and 12|6 C but tell why it is highly unlikely. Calculate the lifetime of the direct transition as a function of the possibility...
  18. 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...
  19. O

    Emission Spectra and the Rydberg Equation

    A student collects diffraction data using a lamp with known emission wavelengths of 425nm, 565nm, 600nm, and 700nm. These lines appeared on her spectroscope at 32mm, 59mm, 63mm, and 69mm (all measured from the same arbitrary 0mm position). With these data she is able to calibrate her...
  20. 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...
  21. J

    Emission of EM Wave: Why Does it Happen?

    In wikipedia's description of transmitter, if an alternating current is given to an antenna, then the antenna radiates off em wave. But why this happens so?
  22. D

    Light emission as wire rope breaks

    I knew the one inch wire rope was under severe strain, that's why I was watching it when it parted (broke). First, a few of the individual steel wires broke with some small time interval between each break. Then more wires broke at a faster rate until the remainder broke all at once. It was...
  23. D

    Calculating coal CO2 emission intensity (kg CO2 emitted/kWh delivered)

    Hi all, Would really appreciate some help on this problem I can't seem to figure out. Brown coal has an energy content of 15MJ/kg, carbon content 65% by weight, burning in a 30% efficient steam power plant. Calculate the CO2 emission intensity (kg CO2 emitted/kWh delivered).Assume complete...
  24. U

    Automotive Some ideas for a CO2 emission reduction device to be attached to cars

    Hi, I and my team-mate have proposed an idea to develop a CO2 emission reduction device to be installed in automobiles. We have mentioned that it will operate on the principle of 'active adsorption of CO2 on charcoal'. However, although the basic scientific principle is pretty simple...
  25. P

    Hydrogen gas emission spectrum

    If a hydrogen spectrum tube is filled with H2 gas and powered on, why do online sources show the tube emitting the spectrum of atomic single H hydrogen (the spectrum defined by the Rydberg formula)? Why not the H2 spectrum? For example, here: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
  26. X

    Beta Decay of He3 Atom: Electron Emission vs. Shell Occupancy

    Does this decay leave the He3 atom with only one electron? The only decay productsas far as I can tell are the electron and antineutrino, so it seems like the atom would only retain the original H3 electron. Now if that's the case, why is the beta decay electron emitted rather than fitting...
  27. B

    Negative Ion Emission: Heat, Piezoelectric Effect & Object Differences

    Will more negative ions emit from an object (like a "negative ion generator") due to heat or piezoelectric effect or will they emit any way? Also, do certain objects give off more negative ions than others?
  28. R

    General Formula for atomic emission spectra

    hi everyone! does a general Rydberg-like formula exist to predict the emission spectrum wavelengths of any atom? if not, why?
  29. A

    Carbon di oxide emission of filament bulbs

    One thing I am not able to understand. Governments advocate the slow phasing out of the filament lamps and replacing them with CFLs.The reason repeatedly cited for this is that the filament lamps contribute to the global warming by way of emitting carbon-di-oxide. But, interestingly, it is...
  30. K

    The color of an apple (light absorption and emission)

    Emission of light from a solid object From my textbook (explaining why an apple is red): We imagine that the red apple in the picture is illuminated by daylight, IE light which contains all the wavelengths of the visible spectrum. The apple is red because the main part of the light it...
  31. P

    Absorption and Emission Spectrum

    When an element is excited by some method, it emits electromagnetic radiations of definite wavelengths. The arrangement of these wavelengths in order of increasing wavelength is called emission spectrum of the element. (as per my book) But, the definition of absorption spectrum, I don't...
  32. T

    Semiclassical approach to emission

    Where can i find something on the calculation of the emission spectrum with the semiclassical approach? Thanks
  33. Y

    What is the chemical formula for car exhaust emission

    What is the chemical formula for car exhaust emission
  34. S

    Energy Emission: Electrons vs Protons

    Hello, I read that if an high energy electron impact with atoms some electron of the atoms can be emitted, does that happen with every high energy particle? For example, using an high energy proton instead of electron, will the opposite charges attract and reduce a bit the energy of the emitted...
  35. O

    Positron emission (Beta + decay)

    Why does β+ decay occur? If protons are stable and all baryons eventually decay to protons, then how is it that protons can 'decay' to a neutron? What causes this to happen? (I assume it isn't as frequent as β- decay, or up and down quarks would be coming and going constantly, and we'd be...
  36. S

    Incandescent bulb heat emission

    Hi all, I have a doubt which I would like to hear your opinion and answers about. So, I was comparing different light sources for my research, and I started thinking about a sentence which I've always taken for granted: incandescent light bulbs waste more than 90% of their power as heat...
  37. R

    What Causes the Beamed Emission of Pulsars?

    Hello everybody. I am searching for an explanation about the beamed emission of pulsars, either in radio and in X-rays bands. I can not find a "standard" reason (with demonstration, eventually) for the beaming of this objects' radiation. Please, can you suggest to me something, or even a link...
  38. A

    What Photon Energies Are Emitted When a Hypothetical Atom Absorbs 7-10 eV?

    A gas of a hypothetical atom in ground state (-14eV) is irradiated with photons having a continuous range of energies between 7 and 10 electron-volts. Photons of which energies will be emitted from the gas?The energy levels look like this: 0-------------------(ionization state)...
  39. O

    Why Are There Only 4 Visible Emission Lines in the Bohr Model for Hydrogen?

    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...
  40. H

    Nuclear decay emission: deterministic modeling?

    Is it possible, in theory, that a radioisotope undergoing nuclear decay (eg. alpha particle emission) can be modeled so as to determine the origin and/or direction of the emitted particle? For instance, perhaps one could model nucleon interactions deterministically and observe that when the...
  41. B

    Is charge conserved in positron emission?

    Consider the reaction: ^{39}_{20}Ca \rightarrow ^{39}_{19}K + \beta^{+} I understand that a proton in the Calcium nucleus is being split into a neutron, which stays in the nucleus, and a positron, which gets ejected. But if you look at the equation above, charge is not conserved. The only...
  42. C

    Calculating the visible emission spectrum for hydrogen

    so the title speaks for itself i hope. my problem is i don't know how to work the formula. what are the ns about?? lamba^-1 = R(n1^-2 - n2^-2)
  43. F

    Spontaneous emission in photonic crystals

    Hello forum, I have a question about photonic crystals. From Wikipedia: "photons (behaving as waves) propagate through this structure - or not - depending on their wavelength. Wavelengths of light that are allowed to travel are known as modes, and groups of allowed modes form bands...
  44. F

    Relation between spontaneous emission, absorption and re-emission

    Hello Forum, when a wavefield is incident of an atom and the photon have the right energy (equal to the band gap energy), the photon is absorbed and disappear... But isn't the photon re-emitted later on and allowed to propagate through the material or does all its energy get lost into heat...
  45. G

    Thermionic emission at same temperature

    As it is known, the thermionic emission (emission of electrons at high temperature) current density in vacuum depends on the temperature and the work function of the material. The work function is a material specific constant. Let's compare thermionic emission with thermal radiation. With...
  46. P

    Cutting edge introductory info re: field emission microscopy and imaging methods

    Folks, I'm self-taught and am currently trying to get up to date about the newest developments in field-emission microscopy and other methods of imaging sub-atomic structures. I'm able to follow (though just barely) Mikhailovskij et al.'s 2009 paper in Physical Review showing electron orbitals...
  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. Q

    Determine the rate of emission of quanta from the station

    Homework Statement A radio station operates at a frequency 103.7MHz with a power output of 200kW. 1)Determine the rate of emission of quanta from the station. 2)If we treat the radio station as a point source radiatng uniformly in all directions, find the number of photons inside a...
  49. T

    Stimulated Emission has no sufficient proof?

    Hi All I was surfing Internet trying to understand why most books i read simply considers that the stimulated photon emission has same properties as the stimulating photon, and treats this simply as an "take as it is". For my surprise, i found this article...
  50. S

    The Hydrogen Atom Ground State: Radiation Emission

    when proton and electron combine to form hydrogen atom(ground state) what is the source of radiation emitted
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