Electron Stimulated Desorption of Excited Hydrogen Atoms from an Alkali Promoted Surface

Abstract

We observe directly the radiation emitted from excited hydrogen atoms following their electron stimulated desorption from an al kali-promoted Ni(001) surface. We observe Lyman α, ß, γ radiation. The line width and energy of the emitted radiation indicate that the hydrogen atoms are well removed from the metal surface at the point of deexcitation. By comparing the desorption cross-section for these states with the desorption cross-section of hydrogen ions we find that the excited hydrogen atoms are emitted directly from the surface rather than resulting from the reneutralization of desorbed ions. The intensity of Lyman α radiation is over an order of magnitude greater than the intensity of Lyman ß and γ radiation suggesting either a higher probability for excitation into the hydrogen 2p state initially or a higher probability of resonance ionization of the higher excited states.