ELECTRON-CAPTURE FROM COHERENT ELLIPTIC RYDBERG STATES

Experimental relative cross sections for electron capture by singly ch arged ions (Na+) from coherent elliptic states of principal quantum nu mber n = 25 are presented. An interval of reduced impact velocities fr om about 1-2 is covered. Absolute reaction cross sections could not be determined precisely, but the eccentricity of the coherent elliptic s tates and their orientation relative to the ion-impact velocity were v aried to expose the dependence of the electron-capture process on the initial motion of the electron. The dependencies on eccentricity and o rientation are generally strong and they vary sharply with impact velo city. Qualitatively, the observations agree fairly well with classical trajectory Monte Carlo (CTMC) calculations, as expected for the large quantum numbers involved, but significant deviations of a systematic nature do remain, showing that some aspects of the capture reactions s tudied are described poorly by classical physics as represented by the CTMC model. [S1050-2947(97)03412-4].