A continuous observation of the metal surfaces has been performed by using a SAM (scanning Auger electron microscope, an Auger version of SEM) to study the ion sputtering phenomena, such as preferential sputtering, a cone formation, and other morphological changes. A 16-mm movie technique and a particular time sequence method for the ion sputtering were introduced to the SAM system. Some applications of the technique to the pure metals (Cu) and alloys (Cu-Sn and Pb-Sn) are demonstrated. It was found that some phenomena characteristic to the ion sputtering can be revealed only with this technique.
An ultra high resolution scanning microscope (UHRSEM) which is composed of a cold cathode field emission electron gun and an in-lens system for specimens, has been introduced. Probe size is estimated approximately 0.5∼0.7 nm at an accelerating voltage of 30 kV by calculation, and it was confirmed experimentally using high atomic number fine particles. Fine metal oxide particles and semiconductor materials were observed directly without any metal coating. A necessity of the UHRSEM has been discussed especially for low voltage SEM (LVSEM) to obtain fine topographical details of the samples, which are very sensitive to the scanning electron beams.
Photoemission studies on the electronic structure of high-Tc superconducting Cu oxides have been made, and the results can be summarized as follows : 1) The Cu 3 d elertrons are localized as a spin-1/2 d9 configuration due to strong intra-atomic Coulomb interaction. 2) However, hybridization between the localized Cu 3 d states and the band-like O 2p states is strong in the ground state, and thus resuts in a net d occupation of about 9.5 and a magnetic moment of about 0.5 μB per Cu atom. This is in good agreement with neutron experiment. 3) Doped holes are predominantly O 2p-like rather than Cu 3d-like. 4) From these, attractive interaction between O 2p holes mediated by fluctuations of the Cu 3d spins would be a most likely candidate for the cooper pairing mechanism.
Abnormal zero-order desorption spectrum (ZODS), which shows constant desorption rate even when the adsorbed amount is decreasing, has been reported for several systems in thermal- or isothermal-desorption measurements. These ZODSs are observed coincidentally with the appearance of liquid-gas phase coexistence region in adsorbate system. Recently, another type of ZODS was observed in the phase-coexistence region between adsorbate-induced-reconstructed- and normallyadsorbed phases of H/Ni (110) system. Examples of these experimentally observed ZODS are summarized. And our interpretation of ZODS is proposed, which is derived on the naive basis of transition state theory and the lattice-gas statistics. The derived rate is known to be different from the conventionally used ones. Therefore, the latter conventional rates are examined and are shown to fail in the explanation of ZODS even qualitatively.
The energy shifts in ionization, electron affinity and excitation observed by photoemission, inverse-photoemission and electron energy loss measurements, respectively, are studied in terms of the total-energy approach (the Born-Haber type energy-cycle). The PES and I-PES shifts are due to the final state effect. It is suggested that the excitation energy is slightly red-shifted (or almost zero), although this is contrary to the results of two papers published before.
The surface state of perovskite-type La1-xSrxCoO3 was investigated by means of X-ray photoelectron spectroscopy (XPS). As for fresh (as-prepared) oxides, the surface composition of A site cations (La+Sr) was larger than the bulk composition, though Sr tended to segregate more easily at the surface than La. It was found that surface state of the oxides was stable at temperatures below 500°C but subject to change drastically at the higher temperatures. When the oxide was evacuated at 800°C, the surface was reduced to (La, Sr)4Co3O10 or (La, Sr)2CoO4 and, in the subsequent cooling under an oxygen atmosphere, the reduced surface layer was reoxidized to a Sr enriched perovskite-type oxide. The surface state was also affected by the calcination temperature in the catalyst preparation. As calcination temperature increased, La content increased while Sr content decreased. This change may be caused by the sublimation of Sr from the surface during the calcination at high temperatures. These changes in surface state and composition were found to lead to the deactivation of catalytic properties.
Molecular forms of Rhodamine B (Rh B) is investigated by means of FT-IR reflection spectroscopy. The cationic form is observed when the red dye is adsorbed on silica surface whereas the zwitterionic form is detected in a mixed crystal of potassium chloride. These observation supports the conclusion in the previous study of the photoacoustic spectroscopy for these powdered samples.