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Finding the recoil energy of an excited atom when it de-excites

  1. Feb 23, 2008 #1
    I know that i am commiting some serious errors in this , but just cant notice them
    suppose we have to find the recoil energy of an excited atom when it de excites

    suppose the total energy of the process is E

    an atom will emit a photon on returning to normal state . energy of the photon is....... e

    recoil velocity of the atom is v;
    mass of the atom is M

    Mv+e/c=0.................momentum conservation...........c=velocity of light.initialy the atomis at rest

    Mv*v/2 + e=E...........energy conservation


    from first equation

    v=-e/(Mc)...........(i)

    thus recoil energy must come out by substituting v

    Me*e/(2*M*M*c*c)

    e*e/(2Mc*c)

    substituting this in energy conservation equation

    e+e*e/(2*Mc*c)=E
    e+e*e/(2*Mc*c)-E=0

    solving for e;
    [tex]\Delta[/tex]=1+2E/(M*c*c)

    whats is the solution ???????
     
    Last edited: Feb 23, 2008
  2. jcsd
  3. Nov 3, 2008 #2
    Re: recoil

    The recoil energy (K) is given as:

    [tex]K = E^{2}_{photon}/2mc^{2}[/tex]

    where mc2 describes the rest mass of the particle. mc2 will be of the order 109 to 1011 eV for atoms and nuclei.
     
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