We report the first observations of synchrotron-radiation-induced photon-stimulated desorption (PSL) of molecular oxygen from the high-$T_c$ superconductor ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{x}}$. Using unmonochromatized synchrotron radiation we observe a time decay in the ${\mathrm{O}}_2$ PSD yield which we interpret in terms of depletion of oxygen sites on or near the surface. The time dependence is best modeled by a sum of three exponentially decaying functions. The lifetimes range from values of <2 sec for the fastest component to 550±250 sec for the slowest component. We derive a cross section for PSD of weakly bound oxygen of 3.5±3 Mb.

• Received 19 October 1987

DOI:https://doi.org/10.1103/PhysRevB.37.5841