IEEE Journal of Quantum Electronics
Single-atom detection by SONRES
Jerry A. Gelbwachs, C. Klein, John E. Wessel
Abstract
The new method of atomic fluorescence detection, called saturated optical nonresonant emission spectroscopy (SONRES), has been modeled for a three-level atom, and experiments on sodium have been conducted that support the model. A rate equation analysis yielded expressions for excited-state atomic populations and saturation intensity. The detection of sodium in buffer gases that promote collisional transfer of excitation between 32P1/2→ 32p3/2both without quenching the fluorescence emission and with quenching was considered. Experimental results are presented for sodium in argon. At -25°C, approximately 180 atoms/cm3were monitored with a S/N of ∼ 15 representing detection at the level of one part in 1017. The signal at this temperature was generated by less than a single atom in the laser beam.