  When optically excited, iodine absorbs in the 490- to 650-nm visible region
of the spectrum and, after radiative relaxation, it displays an emission
spectrum of discrete vibrational bands at moderate resolution. This makes
laser-induced fuorescence spectrum of molecular iodine especially suitable to
study the energy structure of homonuclear diatomic molecules at room
temperature. In this spirit, we present a rather straightforward and
inexpensive experimental setup and the associated spectral analysis which
provides an excellent exercise of applied quantum mechanics fit for advanced
laboratory courses. The students would be required to assign spectral lines,
fill a Deslandres table, process the data to estimate the harmonic and
anharmonic characteristics of the ground vibronic state involved in the
radiative transitions, and thenceforth calculate a set of molecular constants
and discuss a model of molecular vibrator.
