Ionization detection of single atoms by laser radiation using Rydberg states

Single atoms of sodium and ytterbium were detected by the electric-field ionization of atoms from high (Rydberg) states. Sodium and ytterbium atoms in a beam were stepwise excited to Rydberg states by radiation from tunable dye lasers and ionized by electric field pulses. The conditions for maximum ion yield were investigated and implemented in the excitation and ionization processes. The statistics of appearance of atoms in the detection zone was studied for low-density beams under ion counting conditions.