When many of the atoms or molecules in a sample have been excited into a metastable state, a(n) ______________ has occurred.
A) ultraviolet catastrophe
B) population inversion
C) coherent emission
D) incoherent absorption

Question

Quizplus · Accepted Answer

Population inversion is the process where more atoms or molecules in a system exist in an excited state than in a lower energy state, which is a prerequisite for laser operation.

When Many of the Atoms or Molecules in a Sample