A hypothetical atom has two energy levels, with a transition wavelength between them of 580 nm. In a particular sample at 300 K, 4.0 x 1020 such atoms are in the state of lower energy.
(a) How many atoms are in the upper state, assuming conditions of thermal equilibrium?
(b) Suppose, instead, that 3.0 x 1020 of these atoms are "pumped" into the upper state by an external process, with 1.0 x 1020 atoms remaining in the lower state. What is the maximum energy that could be released by the atoms in a single laser pulse if each atom jumps once between those two states (either via absorption or via stimulated emission)?