Abstract

Photoionization in a uniform electric field has been investigated with two-photon excitation through the n = 2 state as the first step. At the field strengths applied, the Stark splitting of the n = 2 state exceeded the spin-orbit interaction, as indicated by the Stark spectrum of the (n = l)-(n = 2) transition (Lyman-α) in Fig. TuGG5-l. The paired structure for σ and ∏ polarization is clearly resolved. The spectrum was obtained by two-step excitation-ionization, H(n = 1) + VUV → H(n = 2) + UV → H⁺ + e, with VUV laser light tunable around the Lyman-α wavelength, as preciously applied.¹

© 1984 Optical Society of America