Some Observations of Double- and Triple-Quantum Transitions

Data are presented which show that it is possible to observe transitions for which $\Delta J=0\mathrm{}$, $\Delta m_J=\pm 2 or \pm 3$ in a molecule characterized by a total angular $J$. It is also possible to observe transitions for which $\Delta F=0\mathrm{}$, $\Delta m_F=\pm 2 or \pm 3$ in an atom characterized by a total angular momentum $F$. In each case the process occurs by the absorption or stimulated emission of two or three equienergetic quanta.