The chemical environment of oxygen in cobalt-containing metal oxides with compositions͑M,MЈϭMn,Ni,Co͒ has been studied by Auger, x-ray and ultraviolet photoelectron, and high resolution electron energy loss spectroscopies. While there is a single type of lattice oxygen in the bulk structure of simple rocksalt and spinel oxides, the nature of oxygen at the surface of the spinel oxides is considerably more complex. Photoemission from core oxygen states in these materials often shows multiple peaks and satellite structure which have been attributed to a range of intrinsic and extrinsic oxygen states. All of these 3d transition metal oxides show a single, intense O 1s core photoemission peak at approximately 529.6 eV. In the spinel materials, a second state at 531.2 eV is also observed and is shown to be intrinsic to the spinel surface and not a result of hydroxylation or other surface contaminant. Similar photoemission features in Fe 3 O 4 were previously attributed to final state effects; however, the nature of the multiple final states remains to be elucidated.

Fig. 2. PCDFB laser emission spectra at several operating temperatures, for pulsed optical pumping with a 200-pm-wide Gaussian stripe pumped at five times the lasing threshold. The spectra for Fabry-Perot lasers (no grating) from the same bar are also shown for comparison (dashed curve).was narrower than for any earlier antimonide mid-IR laser pumped far above threshold, apart from external cavity devices4 Fig. 2 illustrates PCDFB and Fabry-Perot spectra at several temperatures, where the Fabry-Perot linewidths range from 43 nm full width at half maximum (FWHM) at 180 K to 69 nm at 240 K, and the linewidths of a-DFB lasers fabricated from the same wafer' have similar values. At T = 180 K,