Speaker: William Setzer, Thomas Morgan's group, Wesleyan University
Abstract: Understanding the ionization properties of diatomic molecules is of fundamental importance to chemical physics and many spectroscopic applications. Here, I present rotational-state-selective field ionization spectra of highly excited triplet nd H2 Rydberg states. A fast 6 keV beam of metastable c3∏u- 2pπ molecules is excited to v = 0, R(1)nd1 (n = 17-27) Rydberg states by a frequency-doubled tunable dye laser and ionized by a static electric field as large as ~35 kV/cm. For each Rydberg state, we observe, as expected, an ion yield that corresponds to diabatic field ionization into the N+ = 1 continuum. At higher fields, we observed an additional ion yield. A model, which considers a diabatic traverse of the Stark map, expects the N+ = 1 ion yield and allows for characterization of the second ion yield as ionization into the N+ = 3 continuum and the result of a rotational-state population transfer. Candidates for the population-transfer mechanism are discussed.