Emission spectrum Definition and 66 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. P

    I Emission Spectrum & Energy: Exciting Hydrogen Vapor

    By exciting hydrogen vapors with heat or electrical discharges, it is possible to obtain the element's emission spectrum. In it, as can be seen, appear multiple wavelengths, each corresponding to a particular orbital electronic transition. From this it can, therefore, be inferred that heat and...
  2. Pushoam

    Spectral lines in the emission spectrum for an electron at n= 3

    Since there is only one excited electron, it could come from n=3 to n =1directly or n=3 to n =2 and then n=2 to =1. Hence, there could be one or two lines depending upon the path taken by electron. Is this right?
  3. B

    B What Are the Dangers of Spectral Lines from EM Sources?

  4. C

    A Physical explanation of time-correlation function and spectrum

    From my reading of several quantum optics textbooks and spectroscopy texbooks, the emission and absorption spectrum of an atom or molecule are always given in terms of the time-correlation function, for example the emission spectrum of a two level atom is given by: $$...
  5. C

    A Absorption and emission spectrum in quantum optics

    The emission spectrum or resonance fluorescence for a quantum dot, atom or defect center are discussed in many quantum optics textbook, for example see "Quantum Optics" by Marlan O. Scully and M. Suhail Zubairy Chapter 10 , "Quantum Optics" by D. F. Walls and Gerard J. Milburn Chapter 10 and...
  6. ktmsud

    I Continuous Spectrum and Energy levels of Electrons (Energy Bands)

    My book says that emission spectra are produced when an electron in excited state jump from excited to lower energy states. It also states that solids and liquids produce continuous spectra and it depends upon temperature only (is this black body radiation?). I know, Electrons around a nucleus...
  7. muissi97

    Chemistry Why Does UV Light Have More Energy Than Visible Light in an Emission Spectrum?

    The difference in energy between these two lines is that in the ultraviolet spectrum line, there is more energy because it has a shorter wavelength compared to the visible spectrum line as shown in figure 1.1 According to the Niels Bohr's model of the atom(figure 1.7) and figure 1.1, the least...
  8. AN630078

    Hydrogen Emission Spectrum and Electron Energy Levels

    1. The 4th line from the left, being the aqua blue line, corresponds to a wavelength of 486 nm, as blue light has a wavelength in the range 450-495 nm. 2. This is where I am having the most difficulty, I have tried to answer the question comprehensively but I am not satisfied with my answer. In...
  9. B

    Hydrogen emission spectrum calculation

    I've first method I tried was using f = v/λ to find the frequency, then E = hf to find the energy and then using E = (-13.6eV/n^2) - (-13.6eV/n^2) to rearrange and solve for the unknown n. However I got 5, the same as the original entry level. I also tried using 1/λ = R(1/4 - 1/n^2) to solve...
  10. F

    I Understanding Gunn-Peterson through the Reionization epoch

    Into an extra-galactic physics course, I don't understand well the "Gunn - Peterson" effect on the spectrum of high redshift quasars (z greater than 3 or 4, up to the current limit of z = 6-7 I think) The observed fact is that there is an almost total absorption for the photons of the blue part...
  11. Cardinalmont

    B Why are absorption spectra continuous?

    It doesn't make sense to me that absorption spectra are (mostly) continuous. Here are my beliefs. Please tell me which piece/pieces is a/are misconception(s). 1) When light is absorbed, the energy is used to excite an electron to some discrete energy level. 2) To get to this discrete energy...
  12. B

    How do you work out the wavelegth (Franck-Hertz experiment)?

    Homework Statement In a Franck-Hertz experiment carried out with potassium vapour, it is found that the current falls off rapidly at an applied voltage of 1.62V. Calculate the wavelength of the expected spectral line in the emission spectrum of potassium when this voltage is reached. Homework...
  13. AGuglielmone

    B Are all wavelengths of light possible?

    I just had the thought that atoms emit light at quantized levels but that would seem to imply that only certain energy levels could possibly exist instead of a complete spectrum. But, if light is traveling down or away from a gravitational field the frequency gets shifted. Would this make it...
  14. F

    I Why Does a Blackbody Emit Broadband Radiation from Monochromatic Light?

    Hello Everyone, I have some thoughts about Planck's law. The graph describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature T. I think the absorption (or absorbance?) spectrum of an ideal blackbody should be a horizontal...
  15. Willow Wanda

    Why do Christmas lights glow green near a Tesla coil?

    Homework Statement For a high school physics class, I chose to build a tesla coil for a real world application assignment. I was able to build it fairly easily and it turned out great. Before presenting to the class next week, I've been seeing its effect on different types of light bulbs and...
  16. E

    I Only certain emission lines show up in absorption spectrum

    I'm reading Eisberg's Modern Physics and in it, in the atomic spectra chapter, he says: "We have been discussing the emission spectrum of an atom. A closely related property is the absorption spectrum. This may be measured with apparatus similar to that shown in figure (5-1) except that a...
  17. W

    B Light spectrum of planet Earth as seen from space

    Has the spectrum of light that is reflected off planet Earth ever been measured from outer space? (In the same sense that we measure spectra of the light emitted/reflected from other celestial bodies in astronomy). If so, would it be possible that there could be dips in the spectrum resulting...
  18. S

    The emission spectrum of an unknown element

    Homework Statement The emission spectrum of an unknown element contains two lines - one in the visible portion of the spectrum, and the other, ultraviolet. Based on the following figure and what you have learned about Niels Bohr's model of the atom, account for the difference in energy between...
  19. C

    Interference of light, emission spectroscopy prac. report

    Ok, so I've got a practical report due tomorrow and I just wanted to clarify a few things. A bit of background knowledge first. The practical involved taking angular measurements for the emission lines of the Mercury spectrum using the apparatus, a spectrometer and a Mercury spectral tube...
  20. Wrichik Basu

    B Obtaining spectrum of Sodium from Sodium Vapour Lamp

    I learned that two lines in the emission spectrum of Sodium, namely ## D_1 ## and ## D_2 ##, are on the visible region of the spectrum. Can I obtain these lines from a Sodium vapour lamp? I want to use a prism to separate out the individual wavelengths, a no then use a photographic film to...
  21. Z

    Investigation about the emission spectrum of Mercury

    Homework Statement For our investigation, we used a diffraction grating spectrometer to observe the emission spectrum of mercury. We conducted the experiment in a pitch black room to avoid any unwanted light pollution, etc. Whilst conducting the experiment we observed a number of 'faint' lines...
  22. T

    B Why only certain colors in emission spectrum are visible?

    Why are only certain colors of the emission spectrum in Hydrogen visible?
  23. Klupa

    B Light determination for emission spectrum

    Hi all, the title is probably a bit confusing but I was wondering. What determines the type of light emitted when electrons move down electron shells and emit energy? Why isn't all the light emitted the same colour?
  24. N

    B Why Do Stars Show Both Emission and Absorption Spectra?

    When you heat things up, they emit specific wavelengths of light, right? Like when you heat up sodium, it emits yellow. But don't things emit shorter wavelengths of light at higher temperatures? Like how hotter stars are blue and colder stars are yellow. Since stars are mostly hydrogen...
  25. Zack K

    Understanding Starlight: White Light, Double Slit Experiment, and Color Emission

    I've been recently watching videos about white light and the double slit experiment and how it creates a rainbow. It let me to some confusion and I would like some clarification. My questions are: Do all stars like ours produce white light? Would red giants only emit red light and blue giants...
  26. Matthew Adams

    I Emission spectroscopy of an acetylene flame

    Hey there folks! This is my first post so please be gentle... ;-) One of my students has been studying the emission spectrum of an acetylene flame. A gas mixture from both an acetylene cannister & an oxygen canister is fed out to a nozzle, a flame is ignited and we study the emission...
  27. M

    Factors that influence the spectral linewidth of an LED

    So I'm doing up a physics report but i got stuck on this question :( Q: Explain the factors that influence the spectral linewidth of the emission spectrum. i'm guessing that it has something to do with the types of elements used in doping the semiconductor? but i don't know how the theory part...
  28. Lotic7

    I Determine emission spectrum of an LED

    I recently purchased some 660nm LEDs. They look kind of orange not deep red. What is the easiest and cheapest way to determine the emission spectrum. Eventually I wanted to try to use the 660nm LEDs to grow some plants.
  29. Y

    Emission spectrum will change under possible interference?

    Hi, When a molecule makes a transition from high energy state to low energy state, it emits electromagnetic radiation with a certain wavelength, which can be collected as emission spectrum. However, I have a question right here: For any real case, there are quite a number of molecules in one...
  30. C

    Hydrogen Emission Spectrum, Electrons, and Quantized Energy

    I understand that the result of the hydrogen emission spectrum experiment was that only certain wavelengths of light were emitted and that led to the conclusion that electrons emit light when they relax and that they absorb light when they get excited. How does that prove that the energy for...
  31. Y

    How to find emission peak of emission spectrum

    Hi all, I have been getting the emission spectrum of a polymer for a while. The emission peak is very important for that polymer. How do I find the emission peak of the polymer? The reason I ask this question is that if I simply select the highest point, then several points at different...
  32. Y

    Is absolute count of emission spectrum meaningful?

    I am using Renishaw confocal Raman microscope to do photoluminescence spectroscopy of some polymer inside microchannel. When I fix the laser power and exposure time, the absolute count of intensity will change from time to time even for the same sample. I was hoping the intensity should linearly...
  33. Y

    Emission spectrum changes with microscope objective?

    I am using a Renishaw inVia confocal microscope to study emission spectrum of molecules. The excitation wavelength of laser that I use is 532nm. However, I met with a very basic problem. When I use the same material (say plain silicon), and use different objectives (20X, 50X, 100X), then I will...
  34. 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...
  35. 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.
  36. 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...
  37. Entanglement

    Emission spectrum lines of hydrogen

    I was told at school that when a hydrogen electron gains heat energy enough to excite it shifts to a higher energy level, then after a very small period it falls back to its ground energy level, that means all the energy it gains should be lost, but if that is true since hydrogen has an electron...
  38. P

    Emission spectrum wavelengths.

    Something that bugged me when doing this lab. Standard little glass vials of gas, toss it in a 5kV potential make pretty color, look through diffraction grating see the individual wavelengths that are the finger prints of the element. My question however are all wavelengths equally...
  39. S

    Why Does the Continuous Emission Spectrum Depend Only on Temperature?

    why does the continuous emission spectrum depends only on the temperature of the solution and not on the characteristics of the source?i could not understand this.someone please explain me this:rolleyes:
  40. D

    Is an emission spectrum really independent of excitation wavelength?

    I've often read that the emission spectrum of a fluorescent molecule is independent of the wavelength used for the excitation. But what happens in the case of a small Stoke's shift where the excitation and emission wavelengths overlap? If I use a narrow band excitation with a wavelength in...
  41. U

    Orbit about star, emission spectrum of light

    Homework Statement Show that in the Bohr model, the frequency of revolution of an electron in its nth In classical physics, the frequency of revolution of the electron is equal to the frequency of radiation it emits. Show that when n is very large, the frequency of revolution is equal...
  42. 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...
  43. 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 =...
  44. 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
  45. 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...
  46. 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)...
  47. 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)
  48. 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...
  49. F

    What Electron Transitions Occur in Helium's Emission Spectrum?

    Homework Statement The numbers following are the results of a lab experiment to find the spectral lines of Helium in a gas discharge tube. The lines I got were roughly: 703nm, 660nm, 590nm, 500nm, 490nm, 470nm, 450nm. The question is, what possible electron transitions could the...
  50. F

    Wavelength, emission spectrum, electron transitions

    Homework Statement Determine the wavelength (in nm, to one decimal place) of the line in the emission spectrum of the He+ ion produced by a transition from n = 3 to n = 1. Homework Equations I used the Rydberg equation for this, although I'm not sure it is the correct one to use...
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