Homework 1 Solutions

notes about EM waves. Equally valid are arguments about photon detectors at
visible wavelength but not at 500 MHz.
Since the transition is visible the energy spacing between the levels is large (h
time a few 100 THz). At room temperature most of the population is still in the
electronic ground state. Unlike the case of a nuclear spin, the expectation value for
the dipole element is approximately the same as what it would be at 0 K.
18