Ossamu Nakamura

Thermal diffusivity of lead iodide

The thermal diffusivity and thermal conductivity have been determined for lead iodide PbI2, at room temperature, using the photoacoustic spectroscopy. The result shows a thermal diffusivity αs=(25.0±0.4)×10−3 cm2/s, a value very close to other semiconductors of current technological importance. The electrical conductivity is also measured and discussed.

Electron paramagnetic resonance study of chromosilicalite

An electron paramagnetic resonance (EPR) study of crystalline chromosilicalite has been presented with the purpose of characterization of the distribution of Cr3+sites in the solid. In addition, a deconvolution process is described whereby the EPR parameters can be analysed.

In vitro thermal diffusivity measurements as aging process study in human tooth hard tissues

In the present work, the Open Photoacoustic Cell Technique was used to find effective thermal diffusivity of human tooth hard tissues, a thermal variable of great interest in the biological science, and inorganic materials. The aging process of the tooth enamel and dentin was analyzed through its effective thermal diffusivity. The study in vitro of these samples showed an increase and posterior decrease with aging of the samples. The values found for the enamel and dentin samples, varied from (36−55)×10−4 cm2 s−1 and (20−32)×10−4 cm2 s−1, respectively.

Immobilization and photoacoustic spectroscopy of N-(2-pyridyl)acetamide cation complexes bonded to silica gel

N-(2-Pyridyl)acetamide was covalently immobilized onto silica gel giving 1.57 × 10–4 mol of this molecule per gram of silica. This new bidentate chelate extracts MCl2(M = Ni, Co, Cu) from ethanol and acetone solutions. The photoacoustic spectra of the solid complexed samples were obtained in the visible and near-infrared spectral regions and were analysed using ligand field theory. The calculated Racah parameters indicate a tetrahedral geometry for nickel and cobalt and a highly distorted octahedral geometry for the copper complex.

Characterization of the double sulfites Cu2SO3·MSO3·2H2O (M = Cu, Fe, Mn or Cd) by photothermal techniques

Structural, thermal and optical properties as well as the non-radiative relaxation time τR and the characteristic diffusion time τβ of the synthesized double sulfites Cu2SO3 ·MSO3·2H2O (M = Cu, Fe, Mn or Cd) were investigated by photoacoustic spectroscopy. The positions of the bands for each compound were identified upon gaussian deconvolution and by Kramers–Kronig analysis, and the d–d and intervalence transitions were observed. The detection of two absorbing bands with low and high intensities is in agreement with previous results on reflectance for Cu2SO3CuSO3·2H2O. A slight shift is observed in the peak positions and in the measured thermal diffusivity, capacity and conductivity for different Ms and the thermal conductivity decreases with the ionic radius of the M(II) cations.

Photoacoustic spectroscopy of a diacetamide copper complex immobilized on silica gel

Abstract Silica gel-immobilized diacetamide is very effective in extracting copper(II) from ethanol or acetone solutions. The complex formed on the surface was studied by means of photoacoustic spectroscope. The IR and visible spectra gave clear evidence that the cation is octahedrally coordinated with a strong tetragonal distortion.

Dyeing process optimization in natural fiber through the Photoacoustic Spectroscopy

Purpose – The purpose of this paper is to discuss applied statistical design of experiment (DOE) to optimize the process of dyeing in natural fiber through the multidisciplinary photoacoustic technique. Design/methodology/approach – First, the spectroscopy analysis of the dyestuffs was carried out based on the 23 factorial design. Second, the DOE was utilized to find which process variables were most significant in the absorption band’s intensity of the dye. Finally, the impregnation optimization of fiber was carried out based on response surface methodology. Findings – The results showed that the dyeing process is more efficient for samples with lower level of dye concentration and dyeing procedure time. The statistical study of the effect of each preparation factor suggested that the composition of the colors has a pronounced influence in the fiber dyeing. Originality/value – Using the DOE and photoacoustic response in the present work was clearly found and proposes a less expensive dyeing process and t...

Incorporation of oxygen in crystalline zeolitic chromosilicates: optical identification of chromium(VI) by photoacoustic spectroscopy

Incorporation of oxygen to crystalline zeolitic chromosilicates, with oxidation of anchored CrIII to non-interacting CrVI species, has been confirmed by photoacoustic spectroscopy; the dichromate anion being extracted from the chromosilicate with water and identified by precipitation of AgCrO4 and oxidation to CrO5.

Synthesis and spectroscopic characterization of CrIII in crystalline zeolitic silicates

The incorporation of CrIII into the framework of high content silica zeolite is confirmed by electron spin resonance and photoacoustic spectroscopies.