Stark effect in sodium atomic states highly excited by laser radiation

Using two-step excitation of the sodium atom by tuned dye lasers, and fluorescence monitoring of the highly excited states, the polarizabilities of the ²D_3/2 states with n = 8 and n = 9 were measured. The levels of the n = 9 states were smoothly tuned through 20 cm^–1 by increasing the electric field up to 2 kV/cm. The use of the Stark effect as a method of selective stepwise ionization of the atoms by laser radiation is discussed.