The spectra of Mg Kα x rays, emitted in collisions of 33-MeV Mg ions with noble-gas atoms, have been measured using a curved-crystal spectrometer. Quenching of the metastable 1s2p ${}_{}{}^3{}_{}{}^{}P$ state of He-like Mg and the 1s2l2p ${}_{}{}^4{}_{}{}^{}P$ states of Li-like Mg caused the intensities of x rays from these states to decrease, relative to the intensities of x rays from the promptly decaying ${}_{}{}^1{}_{}{}^{}\mathrm{P}$ and ${}_{}{}^2{}_{}{}^{}\mathrm{P}$ states as the gas pressure increased. Quenching cross sections were determined by fitting the observed pressure dependence of the x-ray intensity ratios to a function derived from the rate equation for the production and decay of these states, with additional terms to account for contributions from prompt spectator-electron transitions. The quenching cross sections for the ${}_{}{}^3{}_{}{}^{}\mathrm{P}$ state compare favorably with outer-shell electron-capture cross sections estimated from semiempirical scaling rules and recoil time-of-flight measurements.

• Received 27 July 1988

DOI:https://doi.org/10.1103/PhysRevA.39.1041