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tribution would be sharper on single crystal surfaces.Thermal desorption spectra of CO are shown in Figure 7. Only a single peak was observed around 620 K with small exposures.This peak was shifted to lower temperatures with an increase in CO coverage. Above 1 .O langmuir of CO, the desorption spectra show a shoulder at lower temperatures converging to 510 K. These spectra are quite similar to those on Ir(ll0) reported by Taylor et al.*' They have estimated an activation energy for the desorption of 37 kcal/mol at low coverages. Figure 8 shows the angular distribution of the desorption with 2 langmuirs of CO. The relative peak height of the CO desorption at 600 K is plotted against the desorption angle. It varies as cos 6. The sticking probability is close to unity.23 The adsorption process of CO is not activated. Therefore, the desorption may be expected to obey the cosine law. Acknowledgment.He*(2'S) Penning ionization electron spectra (PIES) and He I photoelectron spectra of some alkanenitriles, acrylonitrile, and 3-butenenitrile were measured. Band assignments were made based on the characteristics of the PIES; the nonbonding orbital of the CN group showed a remarkably enhanced band and the relative activities of the a orbitals were found to depend on the size of the substituent next to the a-bond. It is confirmed that relative PIES intensities depend on the following two factors: (i) the electronic factor, which is mainly related to electron distributions of individual molecular orbitals, and (ii) the steric factor involving the size of bulky groups which protect some orbitals from the impact of metastable atoms.

Measurements of the refractive index of thermally grown oxide after annealing reveal that the density relaxation of the oxide is well described by a stretched exponential decay function. The experiments of two-step oxidation show that oxygen diffusivity in the oxide exponentially decreases with the oxide density. The relation between the oxide density and the refractive index is well expressed by a simple power relation rather than the Lorenz–Lorenz formula.

We have analyzed the reciprocating motion of a magnet levitated above a YBa 2 Cu 3 O x superconductor using a nonlinear mechanical model with a mass, a spring, and a dashpot. We introduced velocity dependence of the pinning effect and the distribution of the pinned flux lines against the strength of the pins into the mechanical model. Improved agreement between experimental reciprocation waveforms and simulated ones was achieved. Nonlinear characteristics of reciprocating motion of the magnet above a superconductor were successfully explained with the improved dragged spring model.