four excited, none at ground level : ABSORPTION

INCORRECT

 The probability that this event actually occurred was about one chance in four. A much more likely event would have been the stimulated emission of a photon from either one of the three excited states with a probability of three chances out of four.

What is most likely to occur when the next photon reaches the system ?

  1. Absorption
  2. Stimulated emission
  3. Double stimulated emission
NOTE:
Technically speaking this distribution among the two quantum states corresponds to complete population inversion, but we had arrived here by a series of improbable events. Therefore, in actuality, this could not form the basis of a practical laser.