Charge transfer into the metastable2Slevel of hydrogen by protons colliding with K and Na

Abstract

We measure the charge transfer cross section for protons in potassium and sodium with the final state being $\mathrm{H}\mathrm{}\left(2s\right)+A^{+}$. Using a crossed-beam experimental method we look at this cross section as a function of proton beam energy from 500 to 2500 eV. Our results for potassium agree with previous experiments and theories in showing two main peaks in the cross section: one of (3.9 ± 1.5)× ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at a proton beam energy of 800 eV, and another of (2.8± 1.1)× ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at a proton beam energy of 2.5 keV. Our results for sodium show a steadily rising cross section with a value of (7.3± 2.5)× ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at a proton beam energy of 2.5 keV in agreement with the prediction of Kubach and Sidis; we do not find the maximum at 700 eV reported by Nagata that agrees with the theory of Kimura, Olson, and Pascale.