Quantum Defect Description ofH3Rydberg State Dynamics

We develop a multichannel quantum defect formulation to describe the collision of a Rydberg or continuum electron with a vibrating and rotating polyatomic ion. We formulate a full rovibronic frame transformation which accounts simultaneously for vibrationally and rotationally inelastic collisions (preionization) and l uncoupling. Interactions among degenerate Rydberg series, arising from Jahn-Teller distortions of molecular geometry, play an important role in the formulation. An application to the ${1\mathrm{s}}^2$ ${3\mathrm{s}\mathrm{A}}_1^{\prime }$→${1\mathrm{s}}^2$ε${\mathrm{pA}}_2^{\mathrm{″}}$,εpE′ Rydberg photoabsorption spectrum of ${\mathrm{H}}_3$ accounts for many of its observed features.