Sequential excitation preparation of molecular energy levels with special structural and chemical properties

Three types of experiments are discussed. Stimulated Emission Pumping (SEP) on H2CO, Modulated Gain Spectroscopy (MGS) on Na2, and sub-Doppler spectroscopy of the Ca+O3 flame. The SEP experiments have reached the intensive data-generation stage. With 10,000 of vibrational excitation, H2CO is shown to behave as a normal mode oscillator in low rotational levels, but exhibits extensive Coriolis mode mixing in J approx. greater than 10, Ka approx. greater than 4 rotational levels. A laser-locking scheme has improved the sensitivity of MGS by a factor of 1000. A new but puzzling assignment has been made of the Ca + 1000 flame orange band system.