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Unit conversion

  1. Feb 25, 2009 #1
    Dear PF members,
    We know that 1 meV = 8.066 cm-1. So now can i say 1 cm = 8.066 meV-1 ????
    thanks for your reply.
    Ps: 1 cm-1 = 0.124 meV.
     
  2. jcsd
  3. Feb 25, 2009 #2
    I'm not sure what you are saying here Rajini because your units dont balance.An eV is a unit of energy.
     
  4. Feb 25, 2009 #3

    ZapperZ

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    This is a common "short form" used in condensed matter/solid state physics, especially in optical conductivity measurement. 1 eV is "equivalent" to 8.0655 x 10^3 cm^-1. It's one of those simplified notation that sets k=h=c=1.

    Zz.
     
  5. Feb 25, 2009 #4
    Whoops....sorry Rajini and thank you ZapperZ.Can you please give me some ideas about where to google to get more information?
     
  6. Feb 25, 2009 #5

    ZapperZ

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    It actually is a straight-forward conversion.

    Start with E=hf.

    So if you have 1 eV = hf, it gives you an equivalence

    1 eV == 2.4 e14 Hz

    but we know that f = c/lambda.

    So 1/lambda = cf = 8.05 e3/cm == 1 eV.

    The list of values of the conversion from 1 eV into frequency, 1/cm, and Kelvin can be found in the inside back cover of Ashcroft and Mermin's Solid State Text.

    Zz.
     
  7. Feb 25, 2009 #6
    Hi, how i calculate (and many ppl. do)..
    we know
    [tex]E=hc/\lambda[/tex]
    and so
    [tex]1/\lambda=E/(hc)[/tex]
    Now by taking E = 1 eV, h in eVs and c in cm/s
    one will get [tex]1/\lambda[/tex] = 8066 cm-1 (for E= 1 eV).
    So 1 meV = 8.066 cm-1
    But my questions is whether the following is correct or not!!!!!???
    1 cm = 8.066 meV-1 [i just reversed the units!]

    thanks for your reply
     
  8. Feb 25, 2009 #7
    yes i solved this problem..sorry
     
  9. Feb 25, 2009 #8
    THank you ZapperZ.There was I thinking it might be something complicated.
     
  10. Feb 25, 2009 #9

    alxm

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    Yes, but remember here that it's (meV)-1 and not milli-(eV)-1,
    just as cm-1 is taken to mean 1/centimeters and not 100ths of 1/m.

    First time I worked with cm-1 I kept being off by a factor of 10,000 for some reason :)
     
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