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. malawi_glenn

    Meson emission, real or virtual?

    Homework Statement Assume that a high-energy nucleon is emitting a pion, i.e. the process N→N+π. Is the pion real or virtual or both? Motivate your answer with a calculation or a good argument. Homework Equations Virtual particles does not obey energy (and momentum) conservation. The...
  2. I

    Black lines in elements' emission spectra

    My understanding of analyzing emission spectra is that when the quantum number of an electron decreases (i.e. when it falls closer to the nucleus) it emits energy. I understand that this is a very basic understanding but I have not yet made it to college, so please bear with me. :) Now, what I...
  3. K

    How do EM waves propagate in spherical emission?

    "Waves" in spherical emission... Hi all, I just thought of this and wondered why it had never occurred to me before. In any source emitting EM radiation (a lightbulb for example), it does so all around it, so a sphere of EM radiation propagates out from the source. However how in the world...
  4. H

    Flame atomic emission question

    my question is : How would you make a 1, 3, 5, 7ppm solution from a 100ppm solution? do i just just this formula: C1V1 = C2V2 to calculate the amount i need? for example, for 5ppm solution => (5ppm) V1 = (100ppm)V2 so for V1, I just choose my final volume to be whatever i like... like...
  5. hagopbul

    Multiple lines in H2 and Hg emission spectra

    I was doing a test about rydberg constants using H2 and Hg light spectrum And in the spectrograph I found that H2 have three spectra and the Hg have 5 spectra And I DON'T KNOW WHY H2 have 3 lines and Hg have 5 lines? (Scientifically). I know it is the numbers of the electrons that...
  6. S

    Does the emission line of an ionized atom depend on the number of electrons?

    Emission line is unique for all elements and i think it depends on the electrons of the elements...my doubt is if an element gains or loses one electron then would the emission line of this ionised atom and the emission line of its neighbor atom in the periodic table is same or not..since the...
  7. D

    What is Meinel System and OH Meinel Emission Bands?

    what is Meinel system? and what is OH Meinel emission bands?
  8. S

    Earliest time of light emission after Big Bang

    Good evening ladies and gents I'm in the process of wrapping my brain around Special Relativity, and I've come across an interesting application having to do with Cosmological Horizons. Basically, the question goes like this: "Assume a time T has passed since the Big Bang and that we are...
  9. D

    Understanding Photon Emission from Atoms

    Hi. This isn't so much a homework question, but more of a conceptual understanding question. Lets say an atom has a ground energy level defined at 0J. The energy levels are: E1 = 0 J E2 = 7.77*10^-19 J E3 = 10.66*10^-19 J E4 = 14.1*10^-19 J E5 = 16.6*10^-19 J Now, if an electron...
  10. H

    Black Body / Emission difference ?

    If I make a ball out of calcium; drill a little hole in it; then heat it up in a suitable [vacuum] environment; I see black body radiation thru the little hole, right? At least up to the melting point of calcium ?? I mean, black body radiation is independent of material, right ? Yet the...
  11. T

    Glow of emission lines vs. hot objects

    "glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)
  12. T

    Glow of emission lines vs. hot objects

    "glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)
  13. P

    Black Holes: X-rays, Gamma Rays & Light Emission

    IF nothing can escape from a black hole's event horizon, then how do x-rays and Gamma rays escape? and how does it emits light? it says in "Brief History of Time" that the light it emits is just at the boundary of the event horizon. So then how does it escape the gravity and reach earth...
  14. Amith2006

    Exploring Neutron Emission and Its Role in K(40,19) Decay | Solution Guide"

    Homework Statement 1)Neutron emission is not a possible mode of decay for K(40,19).Why? Homework Equations The Attempt at a Solution I think it is because the neutron to proton ratio for potassium(40,19) is almost unity(more precisely N/P=1.1). So, neutron emission is not a mode...
  15. S

    Intensity of light constantwhy rate of emission of electrons changes?

    Intensity of light constant..why rate of emission of electrons changes?? Intensity of light constant..why rate of emission of electrons changes as frequency of the incident light increased??... is the rate increase or decrease?? help me.. thanks..
  16. A

    Absorbtion and Emission of Photons

    I'm somewhat confused about the emission of photons when electrons go down an energy level. What sentence could I use to help me comprehend this process? This is what I was thinking: When electrons absorb photons from electromagnetic radiation, the electrons have more energy and thus it moves to...
  17. B

    Comparing Emission Spectrum of Moving & Stationary Hydrogen

    Homework Statement Ok guys, Helping my girlfriend out once again. She(if you haven't seen this before) is in Physics 101...yet, I(have taken all engineering courses) can't figure these out. Their book is absolutely terrible! Please give an answer that I can understand(as I like to learn...
  18. G

    Atoms Energy Emission, Absorption

    I was wondering about the process of atom excitement/ionization. If you have a atom that has 4 energy levels and a emitted photon from a laser that had the wave characteristics (F,L,E) as not the valance electron, but the sub shell below the valance electron (match the sub shell energy gap), can...
  19. D

    Wanted: good book on photon radiation emission

    I own and have read numerous books about quantum electrodynamics and also classical EM. But sadly, I have yet to find a good book that describes how EM generates photon-based radiation. E.g. the process by which a radio wave comes into existence -- at a deeper level -- not just Maxwell...
  20. Q

    Relativistic photon emission

    I’m having some trouble with a question from my special relativity assignment. It relates to the frequency of a photon emitted from an atom which then subsequently recoils. The atom has initial rest mass m0, and loses rest energy ‘e’ in the emission (“e is the difference between the rest...
  21. T

    Life time in spontaneous emission for laser

    As we know, if we have a group of atoms at a moment N(t) in an exited state, it will exponentially decrease according to the relation: N(t)=N(0) exp(-At)=N(0) exp(-t/(tau)) Where A is the Einsteins constant for the spontaneos emission, In my book they defined tau in the relation I...
  22. P

    Temperature Effects of a Doubled Radiation Emission from an HII Region

    If the star ionizing an HII region suddenly doubled the radiation emitted, would that increase or decrease the temperature? I feel like the expansion of the region would cancel out the increased energy, but I don't know.
  23. M

    Radon Emission from Uranium Deposits

    From what I hear Uranium miners are constantly under threat from radiation gas which is released from Uranium mines. What I learned before is that there are 3 types of radiation. Alpha (helium), Beta (electrons), and gamma (photons). What kind of radiation releases radon gas. If its not...
  24. J

    Mapping 21cm Neutral Hydrogen with Radio Telescope

    This semester I'll be doing a lab project using a radio telescope to map out 21cm neutral Hydrogen in the galaxy to make a nice big image of it. (First proper hands on experiment:smile: ). Anyway that's the basic idea of it but I'm hoping in it to try to find something more specific in it...
  25. C

    Emission & Energy levels of Hydrogen Problem

    Homework Statement What values of n are involved in the transition that gives the rise to the emission of a 388-nm photon from hydrogen gas? Homework Equations n=? wavelength = 388nm=3.88x10^-7 m R=1.097x10^7 m^-1 E= hc/ wavelength The Attempt at a Solution E= hc/...
  26. C

    How Do You Calculate Additional Wavelengths in an Emission Spectrum?

    I solved a, but I couldn't figure out b... I've tried different combinations but nothing turned out correctly... Homework Statement The emission spectrum of an unknown substance contains lines with the wavelengths 172 nm, 194 nm , and 258 nm, all resulting from transitions to the ground...
  27. D

    Conditions necessary for emission of EMR

    Homework Statement Sorry if this is the wrong place, I'm new here but I've been given a little paper to write on electromagnetic radiation. I am having trouble finding what the necessary conditions are for the emission of EMR, and kind of don't understand what it's really asking me for...
  28. K

    Hydrogen Atom Emission and Absorption

    QW Why does the emission from hot hydrogen atoms consist of the Lyman, Balmer and Paschen series but the absorption of cold hydrogen atoms consists of just the Lyman series? is it because the cold hydrogen atoms absorb characteristic frequencies and the lyman series involves transitions that...
  29. K

    Question on Emission Spectroscopy

    I have a question which was found on my Pre-lab Q> State the equation that is used to determine the energy content of a packet of light of specific frequency. Tried googling it,but couldn't find the answer.
  30. B

    Time Elapsed between Light Emission and Absorption at Different Frames

    A flash of light is emitted at point O and is later reabsorbed at point P. In frame S, the line OP has a length l and makes an angle theta with the x axis. In a frame S' moving relative to S with a constant velocity v along the x axis: How much time tau' elapses between emission and absorption...
  31. M

    Emission Spectra for Elements and Compounds

    Simply put, does it ever change? That is, does the line spectrum of a particular element or compound ever change? I've been searching all over, but I'm getting different answers! :grumpy:
  32. Amith2006

    Stability of nucleus on emission of elementary particles

    # It is said that atoms of elements of high atomic mass are unstable. So they emit alpha, beta or gamma rays. Suppose an atom emits alpha rays. The binding energy of alpha particle is about 27 MeV(million electron volt). It is said that as a result of this emission, the binding energy per...
  33. E

    Emission spectra - predicting

    Hi there. I'm new to this board so please excuse if this is misplaced, there seems to be too many places to choose from. While browsing my computer I found a little program I wrote when doing year 12 physics that was based on the textbook material about ionization energies. It recurssively...
  34. N

    Identifying an element from Emission Spectrum

    Using data collected from a spectrometer, with a diffraction grating of 100 lines/mm, I have collected a set of data. From this I have calculated wavelengths for the 1st and 2nd order lines of the three brightest visible colors, which were Blue/Violet, Green, and Orange. To complete my lab I...
  35. S

    Why Does 238U Not Spontaneously Decay by Proton Emission

    why doesn't 238U decay spontaneously by emitting a proton?
  36. E

    Tuning an emission spectrum

    Is there anyway of manipulating the emission spectrum of something like a gas by pumping it with a specific input? An argon gas laser, for example, will have lots of emission lines. Is there anyway of singling out groups of those lines without changing the gas? I would imagine such a method...
  37. S

    What is the unidentified XX peak in my temperature variation PL spectra?

    I had done a temperature variation PL (4 to 200 K) on my samples. I have found out that there are three emission line in the PL spectra, namely free exciton (FE), exciton bound to neutral donors(DX) and an unknown peak (let's called it XX). As the temperature was increased from 4 K to 200 K...
  38. K

    How do different materials produce different colored flames when burned?

    why does the burning of different materials often produce flames of different colors? I know that various colors of flames are due to excitation...but how is that applied here? Kat
  39. G

    What's a device for testing lightwave emission?

    I'm looking forward to doing some photography projects indoors, but I'm having a hard time differing between sources of light around me. I suspect that the lighting system in my basement is not as bright as I suspect it to be. Thus, I came to the conclusion that the upstairs room was a lot...
  40. A

    Why is the Emission Spectrum the same every time?

    I'm confused So the atoms becaome excited by absorbing energy, like from a hot flame, so this energy makes an electron (or is it all electrons) in the outer shell (or is it all the shells) move to a higher energy level and when the electron(s) return to its(their) ground state, they give off...
  41. W

    Is Biophoton Emission from DNA a Valid Scientific Concept?

    Hi Guys, I've read a couple random pieces on Biophoton emissions from DNA and was quite interested in the topic. There seem to be quite a few suggestions that this could be some form of inter cell communication system. Before I waste a lot of time reading the wrong material I was hoping...
  42. B

    Emission or Absorption of a Photon - Dipole Needed?

    If photons are emitted or absorbed when a pair or a collection of particles, that are or behave as dipoles, undergo oscillation by some driving force, are there any systems that do NOT use a single or collective dipole oscillation to emit or absorb a photon?
  43. H

    Exploring the Physics of Photon Emission

    When a photon is emitted, where did it come from? Did something cause it to be created and then emitted, or was it inside something and then released? How's it work?
  44. J

    What is the required energy for positron emission?

    In positron emission, a proton is converted into a neutron, a positron, and a neutrino: p --> n + e + v this conversion occures only in a nucleus, because this process consumes energy (the neutron and positron have a higher mass than the proton). The energy needed is twice...
  45. S

    Exploring Atomic Emission Spectra: Neon vs Helium & Electron Configuration

    Why does neon have more spectral lines than helium? Is the atomic spectrum based on an element's electron configuration?
  46. G

    How to measure an emission spectrum?

    Say I have a spectrophotometer that has a grating monochromator. If I want to measure emission instead of absorption from a lamp, could I just remove the exit slit? By removing the exit slit, doesn't all of the light just hit the sample?
  47. P

    Experimental Set-up for EMISSION & REFLECTION Spectroscopy: Is it Easy?

    Hi, I went to my proff to ask for my master thesis, he told me that you yourself have to do the experimental set-up for EMISSION AND REFLECTION SPECTROSCOPY ,,,but I am not that experienxed, anybody knows is it an easy task or...?
  48. F

    A thermodynamic approach to spontaneous emission

    any isolated macroscopic system, like a large group of atoms, always tends to reach a state that has the maxium entropy. if the electrons in this group of atoms are excited, they will give out their energy so that more degrees of freedom are activated, hence the entropy of the whole system...
  49. A

    Gamma ray emission which is confusing some scientists

    i heard some breaking news about a gamma ray emission which is confusing some scientists. did anyone heard about it?
  50. J

    Calculating Solar Neutrino Emission Using p-p Chain Energies

    Does anyone have a website which explains how to calculate the solar neutrino emission per second using the energies given in the p-p chain? thanks
Back
Top