X-ray absorption fine structure and photon-stimulated ion desorption from solid MoO3 at molybdenum 3p1/2, 3p3/2 and oxygen 1s edges

We investigated photon-stimulated ion desorption (PSID) from solid MoO3 following Mo 3p1/2, 3p3/2 and O 1s inner-shell excitations. The photon-energy dependences of O+ ion desorption yields were measured using quadrupole mass spectrometry. Near-edge X-ray absorption fine structure (NEXAFS) spectra were measured by the total electron yield method and were compared with the desorption yield curves. Relatively high desorption yields were observed in O 1s → eg resonance compared with that in O 1s → t2g resonance, while no enhanced yields were observed in either the Mo 3p1/2 or Mo 3p3/2 edge. The enhancement effect in the O 1s → eg resonance was attributed to fast bond breakage induced by the antibonding nature of the σ∗-like eg orbital. On the other hand, the non-enhancement following the Mo 3p1/2 and 3p3/2 edges was ascribed to the de-excitation of the excited electrons via very fast Coster-Kronig transitions, which can take place only following Mo 3p1/2 and 3p3/2 excitations.