Depopulation of rubidium Rydberg states by CO molecules: An experimental and theoretical study

The quenching cross sections of highly excited Rb ns(25≤n≤45) and Rb nd(23≤n≤44) states by CO, a weak polar molecule, are measured, and these experimental data are compared to theoretical predictions where the main process responsible for the quenching is taken to be the Rydberg-electron-CO interaction. It is shown that the long-range Rydberg-electron-molecular-dipole interaction is often dominant leading mainly to n-changing and, to a lesser extent, to Rydberg ionization via quasiresonant molecular rotational transitions. It is also shown that the Rydberg-e^- ---molecular-quadrupole interaction is negligible and the short-range interaction leading to l-mixing processes is less efficient. The agreement between experimental and theoretical values is quite satisfactory.