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Electromagnetic Absorption Frequency

  1. Mar 29, 2014 #1
    Hi, I have just registered to ask something that I can't find the answer anywhere.

    As you know, microwaves are absorbed by water molecules because of its shape and angles etc. I wonder which wavelength can be absorbed by nitrogen molecules in the air or at least need to learn a method to calculate.

    Thank you.
     
  2. jcsd
  3. Mar 29, 2014 #2

    UltrafastPED

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    Search for "Molecular nitrogen absorption spectrum".

    You will find lots of details at NIST:
    http://webbook.nist.gov/cgi/cbook.cgi?ID=C7727379&Mask=1000

    You can forget calculations unless this is your research specialty - but see this paper:
    "On the complexity of the absorption spectrum of molecular nitrogen"
    http://www.nat.vu.nl/en/sec/atom/Publications/pdf/Vieitez-08-ML.pdf

    However, this lecture has a very simple formula on page 8; of course it only gives one frequency, so it is based on a very simple model: http://www.geo.mtu.edu/~scarn/teaching/GE4250/absorption_lecture.pdf

    But the lecture is also worthwhile - it provides a great deal of information, but not much on N2.

    Also see "The spectrum of molecular nitrogen": (behind paywall)
    http://scitation.aip.org/content/aip/journal/jpcrd/6/1/10.1063/1.555546
     
  4. Mar 29, 2014 #3
    Thanks UltrafastPED.
     
  5. Mar 30, 2014 #4
    Absorbtion_Frequency.png

    When I calculate, I get a result of wavenumber in terms of s/(m√m) whereas it actually in 1/m. How can it be correct?
     
    Last edited: Mar 30, 2014
  6. Mar 30, 2014 #5

    UltrafastPED

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    I don't know where that equation came from, and I don't trust it.

    Search for Chapter 6 Ideal Diatomic Gas;
    This lecture goes through a typical derivation process ... if you read it carefully you may find out how the above formula was generated, and its limitations.
     
  7. Mar 30, 2014 #6
    Last edited: Mar 30, 2014
  8. Mar 30, 2014 #7
    Is there anyone to verify?
     
  9. Mar 30, 2014 #8

    UltrafastPED

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