Laser photoionization detection of individual sodium atoms via Rydberg states
Bekov G.I., Letokhov V.S., Mishin V.I.
Individual atoms have been registered for the first time by using the method whereby the atom is ionized by an electric field from high-lying (Rydberg) states. Sodium atoms excited to the 13d state by radiation from pulsed dye lasers were ionized by an electric-field pulse. 3-5 sodium atoms from the atomic beam were registered in the observation region.