Three-photon double-resonance spectroscopy of autoionizing Rydberg states inH2

Abstract
A new three-photon double-resonance excitation scheme for H2 is combined with time-of-flight ion detection and is used for high-resolution spectroscopy of autoionizing and field-ionizing Rydberg states. Using modest laser powers, we have achieved a Doppler-limited resolution of 0.15 cm1.