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Exponentially damped dipole - line broadening

  1. Apr 9, 2015 #1
    For an EM wave close to the transition frequency ##\omega_{21}##, we assume the dipole moment to be exponentially damped and oscillating:

    [tex] p(t) = p(0) e^{-\frac{\gamma}{2}t} cos(\omega_0 t) [/tex]

    Why do we expect the electric field to be proportional to ##\dot p##?

    Taken from my lecturer notes on laser and atomic physics:

  2. jcsd
  3. Apr 10, 2015 #2
    If a dipole moment changes(it is created by charge accelerations), it emit EM wave in classic treatment. Therefore we can get E(t) proportional to dp/dt.
  4. Apr 10, 2015 #3
    Please explain the "classical treatment".
  5. Apr 10, 2015 #4
    In classical physics accelerated charges can emit EM waves, it is used in making antenna. A dipole changes with time is a antenna and its behavior is explained by classical physics compleatly. Therefore if you use ' electric field to be proportional to ##\dot p##', you consider atoms like antenna or in other words you use classical treatment of atoms.
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