Formation of the Langmuir monolayer, and structure of the Langmuir-Blodgett (LB) films of Tetra-t-butyl metallophthalocyanines (MTBP) were investigated by the surface pressure-area isotherm and X-ray diffraction (XRD) method, respectively. We obtained a well-defined monolayer on the subphase at concentrations of 5 .EM for the CuTBP and 2.5μM for Co, Zn, and VOTBP solutions. CuTBP yields a well-defined monolayer, due to formation of twodimensional aggregates on the surface where the limiting area of the monolayer is much greater than the intrinsic side area of MTBP. Since intensity of the XRD was so small, the LB layers with one to three layers may not be welloriented. An annealing procedure refined molecular organization of LB films significantly.
Mg/Al-layered double hydroxide with interlayer carbonate (Mg/Al/CO3-LDH) is synthesized with atomic ratio Mg/Al=2, 3 or 4. In situ high temperature powder X-ray diffraction (in situ HTXRD) patterns of Mg/Al/CO3-LDH reveal that the solid phase having hydrotalcite-like layered structure (Phase I) is unstable when the temperature of the solid sample is elevated. Immediately after Phase I disappears, another solid phase (Phase II) grows and becomes predominant. In the direction of c-axis, Phase II has the basal spacing d=0.659 nm which is smaller than that of Phase I. Mixed solids of MgO and a spinel (MgAl2O4) are observed after Phase II degrades. Two endothermic peaks both of which are associated with weight loss appear below 400° in the result of differential thermal analysis/thermal gravimetry (DTA/TG). Phase II is formed at the endotherm of lower temperature and degrades at that of higher temperature. Phase II is unstable at room temperature and transits to an amorphous phase slowly after days of storage in a dry condition. It is observed that a very small part of this amorphous phase transits to Phase I in the same dry condition. Solid state chemistry of the synthetic Mg/Al/CO3-LDH is investigated by means of in situ HTXRD, DTA/TG and X-ray photoelectron spectroscopy (XPS).
The oxygen-nonstoichiometry of La1-xSrxCoO3-δ was investigated by X-ray photoelectron spectroscopy (XPS) analysis, thermal analysis (TGA-DTA) and transmission electron microscopy (TEM). The results of thermal analysis showed that the sharply weight losses in LaCoO3-δ were decreased by Sr substitution. The Co 2p and valence band XPS spectra of LaCoO3-δ suggested that the annealing at 523 K in 20% O2-80% N2 gas increased the oxygen contents and then low-spin ions. On the other hand, the Co 2p and valence band XPS spectra of La0.8Sr0.2CoO3-δ were not changed by this annealing conditioned. Also, TEM observation indicated the change of crystal structure by Sr substitution. These results suggested that the Sr substitution affected the oxygen defects on the oxide surface.
In this article, we show the mechanism for the observation of subsurface structures by scanning tunneling microscopy (STM), which has not been explained by common sense of STM. It is clarified that the properties of electrons as waves, especially, qualitative difference between nano-scale and atomic-scale waves and 3-dimensional tunneling phenomenon in STM play important roles in observing subsurface structures by STM. As examples, we discuss moire patterns in lattice-mismatched systems and the oscillations observed around bulk impurities in semiconductors.
This overview article outlines a quantitative XPS analysis method for alloys covered with a homogeneous surface oxide film over which a contaminant carbon layer exists. The thicknesses of the surface oxide film together with the contaminant layer, compositions of the surface film and near interface region of the alloy under the surface film can be determined by this method. Moreover, a method for energy calibration of a spectrometer and a method to determine photoionization crosssections for the quantitative analysis are explained. Examples of the application of the quantitative analysis are the determination of surface compositions of Fe-base alloys under several conditions, sputter-deposited Ta-Mo alloy surfaces after mechanical polishing and immersion in a concentrated HCl solution, and meaning of the film thickness of porous corrosion products. Investigation of the origin of extremely high corrosion resistance of sputterdeposited Cr-valve metal alloys examined by the precise binding energy determination, and a non-destructive depth analysis by the angle-resolved method is also presented.
The studies on L-edge XANES spectra of Mo, Ni and Cu species are reviewed. In case of Mo L3-edge XANES, a white line of the spectrum is assigned to the electron transition mainly from Mo 2 p to Mo 4 d. Therefore, the split of white line is interpreted to be the split of vacant d orbitals of hexavalent molybdenum ions. This simple interpretation of XANES spectrum allows to characterize the molybdate species on MgO, Al2O3, SiO2 and TiO2.On the other hand, the works on 3 d transition metals such as Ni and Cu are not abundant and the interpretation of the spectra is not simple. The reason is that the absorption phenomenon includes the interaction between core electrons and partially filled 3 d orbitals, which arises many kinds of transitions other than the simple 2p-3 d transition. However, the spectra of some Ni and Cu complexes are simulated by theoretical calculations. In case of Cu oxide complexes, d-holes are discussed relating to the superconductivity.
Studies of surface photochemical reactions induced by core excitation have developed with the advance of synchrotron radiation technique over a range extending from vacuum ultraviolet to soft X-ray. Studies of the photon stimulated ion desorption (PSID) have been carried out mainly on the basis of the initial excitation energy dependence of the desorption yield. In particular, site-specific reactions have been found in PSID following core electron excitation. This is very interesting from the viewpoint of the control of chemical reactions using monoenergetic photo-excitation. The Auger stimulated ion desorption (ASID) mechanism is widely proposed as a model of PSID. As the Auger final state is directly related to the ion desorption in this model to elucidate the PSID mechanism, it is essential to get the information about the Auger final state. In this article, we have described about PSID of formic acid induced by carbon core excitation using ion TOF method and about PSID of condensed H2O induced by oxygen core excitation using Auger electronphotoion coincidence (AEPICO) method.
The paper describes a technique to visualize subbands in semiconductor superlattices, which consists of a photon counting method to measure extremely weak photoluminescence (PL) and an image processing using a personal computer for visualization. The technique has been applied to measure the electric-field dependence of the subbands for GaAs/AlAs superlattices with layer thicknesses of 6.8 nm/1.7 nm (sample 1), 6.2 nm/3.4 nm (sample 2) and 6.0 nm/5.0 nm (sample 3), respectively. The field effects of the subbands such as the resonance and Stark-ladder transition are clearly visualized from the PL images. We observed the PL emission between the second Γ(Γ2) and heavy hole (hh1) states due to the resonance between the ground Γ(Γ1) and Γ2 states, and the PL emission between the ground X (X1) and hh1 states due to the resonance between X1 and Γ2 states. Furthermore, we observed the PLs from the Stark-ladder transitions between the Γ1(+1) and hh1 states and between the X1(+1/2) and hh1 states. This technique is useful for studying electronic states in semiconductor superlattices.
The Wide View Film, a novel optical compensation film for TFT-LCDs was developed to realize wide viewing angle characteristics, without sacrificing brightness of LCDs, utilizing negative birefringence of a discotic liquid cristal. The optical compensation of the Wide View film is to make the coating layer of negative birefringence material have the same orientation structure as that of TN liquid crystals in dark state of a TFT-LCD so that all components of positive birefringence of TN liquid crystals can be compensated. It was found that thin coating layer can be made of discotic liquid crystals which align obliquely and optically in high order. Therefore discotic liquid crystals were utilized as the negative birefringence material for the WV film. In this paper we describe mainly the characteristics and behavior of discotic liquid crystals on alignment layers and the application of the thin coating layer to optical compensation film for improving the viewing angle of TFT-LCDs.