Dynamics of OH(2pi)-He collisions in combined electric and magnetic fields.

We use accurate quantum mechanical calculations to analyze the effects of parallel electric and magnetic fields on collision dynamics of OH(2pi) molecules. It is demonstrated that spin relaxation in 3He-OH collisions at temperatures below 0.01 K can be effectively suppressed by moderate electric fields of order 10 kV cm(-1). We show that electric fields can be used to manipulate Feshbach resonances in collisions of cold molecules. Our theoretical results can be tested in experiments with OH molecules in Stark decelerated molecular beams and electromagnetic traps. PACS numbers: 33.20.-t, 33.80.Ps.

Raman association of H2 in the early universe.

We investigate the contribution made by Raman scattering to the formation of molecular hydrogen in astrophysical environments characteristic of the early stages of the evolution of the universe. In the Raman process that we study, a photon is scattered by a pair of colliding hydrogen atoms leaving a hydrogen molecule that is stabilized by the transfer of kinetic and binding energy to the photon. We use a formulation for calculating the photon scattering cross section in which an infinite sum of matrix elements over rovibrational levels of dipole accessible electronic states is replaced by a single matrix element of a Green's function. We evaluate this matrix element by using a discrete variable representation.