Collisional quenching of metastable x-ray emitting states in a fast beam of He-like fluorine

High resolution x-ray spectral measurements are used to determine the relative intensity of He-like fluorine x-ray transitions, 2 3P1 → 1 1S0 and 1P1 → 1S0, produced in fluorine collisions with Ne, Ar, and Kr gas targets at various pressures and in thin carbon foils and a thick carbon slab. The relative intensities are observed to be strong functions of both target density and incident charge Z. These effects are attributed to strong collisional quenching of both initial states by subsequent large impact parameter collisions. The data permit extraction for the first time of the total quenching cross sections (sigma/sub Q/) for fast fluorine ions in both states. A strong enhancement of the relative intensity of the 2 3P1 is observed for F7+ projectiles. This strong enhancement is attributed to selective excitation of metastable states in the beam, i.e., 1s2s 3S1, into the 1s2p 3P1 state. Finally, the data for foil and solid targets are used to obtain new information on the excitation states of ions moving in solids. High resolution measurements of the radiative electron capture (REC) peak are reported and analyzed for the first time. 3 figs, 1 table