Hideyuki Ishida

Raman spectra of graphite edge planes

The Raman spectrum of the graphite edge plane is different from that of the cleaved basal plane because the 1355 cm−1 and 1620 cm−1 bands are clearly observed. These spectral features of the edge plane have been interpreted to be due to the structural imperfection caused by polishing. In the present work, the Raman spectra of the edge planes prepared by various methods were systematically studied. As a result, it was concluded that the observed spectral features of an edge plane were mainly due to the discontinuity of graphite planes that inevitably exists at the edge. It was also demonstrated that either the degree of graphitization or the orientation of graphite planes can be evaluated by the Raman spectra of graphite materials. These findings were applied to the characterization of the radial heterogeneity of a graphite fiber and the interfacial analysis of a carbon-carbon (C/C) composite.

Raman spectra of diamondlike amorphous carbon films

Raman spectra of diamondlike amorphous carbon (a‐C) films prepared under atmosphere with various hydrogen gas content have been measured as a function of excitation wavelength. The Raman spectral profiles vary with excitation wavelength depending on electronic absorption spectra associated with π‐π* electronic transitions. Dependence of Raman spectra on excitation wavelength is interpreted in terms of π‐π* resonant Raman scattering from aromatic rings with various sizes rather than polyene chains. The relative intensity of a 1400 cm−1 band against a 1530 cm−1 band is found to decrease with an increase of sp3 content in a‐C films. It is shown that the relative intensity can be used as a parameter for sp3 content.

An Application of Surface-Enhanced Raman Scattering to the Surface Characterization of Carbon Materials

Surface-enhanced Raman scattering (SERS) has been successfully applied to the surface characterization of carbon materials such as highly oriented pyrolitic graphite, pyrolitic graphite, glassy carbon, diamond, and carbon fibers by the evaporation of Ag island films onto the surface. The surface chemical and morphological structure of carbon materials has been parallelly characterized by electron energy loss spectroscopy, x-ray photoelectron spectroscopy, and field-emission scanning electron microscope. Raman scattering from the outermost surface of carbon materials is found to be remarkably enhanced by the presence of Ag island films (50–100 Å). The chemical and crystal structure change of graphite and diamond by argon-ion etching has also been studied by the enhanced Raman spectra. The obtained results demonstrate the possibility of using SERS with the Ag overlayer method as a new high-sensitivity surface probe for various kinds of industrial materials.

Characterization of anisotropic stress around Si trenches by polarized Raman spectroscopy

Polarized Raman spectra around trenches formed on (100) silicon wafers have been measured and it has been found that the peak frequency shift varies with the polarization configuration, suggesting that anisotropic stresses occur around the trenches. The different stress components have been calculated by the use of the polarization Raman technique and it was found that the stress distribution of each component approximately agrees with that of each component simulated by a finite element method. Polarized Raman spectroscopy is a powerful technique for the estimation of an anisotropic stress of an electronic silicon device in situ.

Photochemical formation of silver metal films from silver salt of natural high molecular carboxylic acid

Thin films of silver salt of alginic acid, a typical high molecular carboxylic acid in nature, were photolyzed by 253.7 nm light. On irradiating with a 15‐W sterilization lamp in air at relative humidity of more than 70%, the silver alginate films first became yellow‐brown colored due to formation of photolytic colloidal silver particles. When irradiation was continued, the irradiated surface of the films finally changed into clear silver mirror. The morphology of these films was observed by means of a high‐resolution scanning electron microscope. Colloidal silver particles (10–50 nm diam) formed by a short‐time irradiation were sparsely distributed at the film surface. As a result of prolonged irradiation for ∼180 min, film surface was covered with aggregated colloidal silver. The x‐ray diffraction study of the irradiated films revealed sharp diffraction lines, indicating that the colloidal silver was in a highly crystalline state. A preliminary observation of a microtomed cross section of the film showe...

The study of the thermal oxide films on silicon wafers by Fourier transform infrared attenuated total reflection spectroscopy

Fourier transform infrared attenuated total reflectance technique was used to measure the SiOH and SiH contents in the thermal oxide films grown on Si wafers. It was found that the SiOH groups in the bulk could be eliminated by annealing at 850 °C, whereas SiOH at the Si/SiO2 interface could only be removed by annealing at 1000 °C. It was also found that SiOH and SiH groups were generated in the thin oxide film by γ‐ray irradiation. The presence of H or H2 in SiO2 is necessary to explain the result.

Dynamic Step-Scan Two-Dimensional Fourier Transform Infrared Studies of Uniaxially Drawn Poly(ethylene terephthalate) Film

Dynamic infrared spectra of uniaxially drawn poly(ethylene terephthalate) (PET) under a sinusoidal strain were examined. A very intense dynamic band at 973 cm−1 assigned to the trans C-O stretching mode indicated stress-induced high mobility around the C-O bond in the ethylene glycol units. It was supposed that derivative-like skeletal bands observed in the dynamic spectra originated from the stress-induced frequency shift. Two-dimensional correlation analyses of the dynamic spectra were also carried out and revealed that the phenyl ring 18a band at 1018 cm−1 and the phenyl ring 19b band at 1410 cm−1 were composed of three and two independent components, respectively. The correlation peaks between the phenyl ring and CH2 vibrational modes showed that orientation of the methylene group in the ethylene glycol unit, induced by mechanical stretching, is faster than that of the phenyl ring in the terephthalate unit.

Dynamic FT-IR Spectroscopic Studies of Silk Fibroin Films

Dynamic FT-IR spectra in the amide I region were measured for silk fibroin cast films. Phase analyses of the dynamic spectra were carried out in order to separate them into several components which are due to the secondary structures of fibroin. These observations showed that peak positions of the amide I bands were in good agreement with those obtained by Fourier self-deconvolution procedures. In conclusion, phase analysis of dynamic FT-IR spectra is a powerful technique for separation of highly overlapping bands.

Formation of silver metal films by photolysis of silver salts of high molecular weight carboxylic acids

Abstract The photochemical formation of silver metal films from silver salts of high molecular weight carboxylic acids has been studied. On irradiation with a low pressure mercury lamp in wet air at room temperature, the films first became yellow-brown in colour owing to the formation of colloidal silver. After prolonged irradiation, the irradiated surface of the silver salt films of natural high molecular weight carboxylic acids (silver alginate, silver pectate) readily changed into silver mirrors. When silver alginate films were photolysed at 77 K, a broad absorption band below 600 nm and a small peak near 335 nm, probably due to silver clusters, appeared. In this method, silver atoms in the various aggregation states (atoms, clusters, colloids, bulk metal) can be formed by changing photolysis conditions. The preparation of matrix-supported silver films reported by other research groups has been reviewed briefly.

FT-IR-ATR observation of SiOH and SiH in the oxide layer on an Si wafer

FT-IR-ATR (Fourier transform infrared attenuated total reflectance) technique was used to measure the SiOH and SiH contents in the thermal oxide films grown on Si wafers. It was found that the SiOH groups in the bulk could be eliminated by low temperature annealing, whereas SiOH at the Si/SiO2 interface could only be removed by high temperature annealing. It was also found that gamma ray irradiation generated SiOH and SiH in the thin oxide film.