Final Report Summary - CORYPHEE (Cold Rydbergs: photoionization, electronic spectroscopy and electrostatic trapping)
In the realm of this research project, we have contributed to the development of experimental methods to manipulate the translational motion and internal (rotational, vibrational and electronic) degrees of freedom of cold (temperatures of less than 1 K) atomic and molecular samples with the goal of carrying out precision measurements of ionization energies and of studying atomic and molecular photoionization dynamics with an unprecedented degree of details. In particular, we have developed two original methods with which supersonic beams of atoms and molecules can be decelerated to low velocities in the laboratory frame and then loaded in electric or magnetic traps at low temperatures. The first method, multistage Zeeman deceleration was pioneered in my group, and relies on the application of carefully tailored current pulses through long arrays of solenoid to slow down supersonic beams of free radicals, i.e. atoms or molecules with one or more unpaired electrons which are subject to the electron Zeeman effect. Two particular achievements were the deceleration and magnetic trapping of beams of H and D atoms at 100 mK and the generation of slow, and velocity tunable beams of O2 molecules prepared in a single magnetic sublevel of a single spin-rotational level of the ground electronic state. The second method, originally developed in a collaboration between the group of Prof. Softley (Oxford University) and my group, exploits the very large electric dipole moments of atomic and molecular Rydberg states to decelerate supersonic beams of atoms and molecules and store the Rydberg atoms and molecules in electric traps at temperatures of about 100 mK. Major achievements were the electric trapping of molecular hydrogen and the study of the decay of high atomic and molecular Rydberg states by radiative and nonradiative processes over extended periods of time. In the context of these studies we have also carried out the most precise measurements of ionization and dissociation energies ever carried out in a molecular system. Our determination of these quantities for molecular hydrogen (H2, HD and D2) have stimulated theoretical work in other groups and have become reference quantitites to test ab initio calculations including relativistic and quantum-electrodynamics effects. A very recent achievement was the development of chip-base architectures to decelerate and trap Rydberg atoms and molecules and to manipulate them coherently with microwave radiation.