Hideo Tashiro

Effects of divalent metal ions on chlorophyll a fluorescence in isolated spinach chloroplasts

Abstract The effects of divalent metal ions on the yields of chlorophyll a fluorescence were investigated in isolated spinach chloroplasts at room and liquid nitrogen temperatures. Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Mn 2+ increased the yields of fluorescence emission at 684 and 695 nm from pigment system II and decreased that at 735 nm from pigment system I. Al 3+ showed similar but less significant effects on the fluorescence yields. Zn 2+ and Cd 2+ showed no significant effect on the fluorescence yields at concentrations lower than 5 mM. In accordance with the results of our previous study concerning the effects of Mg 2+ on the excitation transfer in the chloroplasts, it was concluded that ions of alkaline earths and manganese suppress the excitation transfer from bulk chlorophyll a of pigment system II to that of pigment system I.

Excitation wavelength-dependent changes in Raman spectra of whole blood and hemoglobin: comparison of the spectra with 514.5-, 720-, and 1064-nm excitation

Raman spectra of whole blood and oxy-hemoglobin (Hb) were measured under the same conditions with visible (514.5 nm) and near-infrared (NIR; 720 and 1064 nm) excitation, and the obtained spectra were compared in detail. The Raman spectrum of blood excited with visible light is dominated by very intense bands due to carotenoids, so that it was difficult to obtain information about Hb from the spectrum. The Raman spectra of whole blood and oxy-Hb excited with 720 nm light are very close to each other; both spectra are essentially Raman spectra of the heme chromophore that is preresonant with Q bands. Qualitative spectral analysis including band assignment and investigation of nature of resonance effect were carried out for the Raman spectra with 720 nm excitation. The spectra of whole blood and oxy-Hb excited with 1064 nm light contain contributions from nonresonance Raman spectra of the heme chromophore and Raman spectra of proteins. The 1064 nm excited spectra of blood and oxy-Hb are similar to each other but different in some features. For example, bands due to protein appear stronger in the spectrum of whole blood than in that of oxy-Hb which does not contain protein except globin part. The comparison between the 514.5, 720, and 1064 nm excited Raman spectra reveal that the excitation wavelength of 720 nm is more practical than that of visible light and 1064 nm in the Raman analysis of Hb, such as oxygenation, specially in situ measurement.

Biomedical applications of a new portable Raman imaging probe

Abstract This article reports the outline of a new portable Raman imaging probe and its applications. This probe may be the smallest and lightest Raman imaging probe in the world. It is equipped with an interchangeable long-working distance microscope objective lens. The irradiation area is about 45 and 90xa0μm and the spatial resolution is 1xa0μm. In the present study, the Raman imaging probe was used to obtain a Raman image of diamond particles and a Raman mapping of carotenoid in Euglena .

Raman Mapping Study of Compatibilized and Uncompatibilized Polymer Blends of Nylon 12 and Polyethylene

Raman mapping images have been obtained for compatibilized and uncompatibilized polymer blends in films of Nylon 12 and high density polyethylene (HDPE) (blend ratios were 20/80, 50/50, and 80/20). A total of 400 Raman spectra were measured for each sample with areas of 100 μm2 and in step sizes of 0.5 μm (for 20 × 20 probe spots). To develop the Raman mapping images, the intensity ratio of two bands, a band at 1635 cm−1 due to Nylon 12 (amide I mode) and that at 1296 cm−1 arising from both HDPE and Nylon 12 (CH2 twisting) is used. The Raman mapping images of the uncompatibilized polymer blends show a clear “sea-island” structure while those of the compatibilized polymer blends exhibit a compatibilized structure. The Raman mapping images enable simultaneous exploration of the morphology and molecular structure of the blends. We have also developed a Raman mapping image that represents the variation of crystallinity in the uncompatibilized film.

Wide-Band Frequency Response Measurements of IR and FIR Detectors by Diode-CO2 Laser Heterodyne Detection

By mixing tunable diode laser radiation and CO2 laser radiation, wide-band heterodyne signals were generated for precise frequency-response measurements of fast infrared detectors. Measuring capability of frequency range over 1 GHz was demonstrated using HgCdTe and Ge(Ga) detectors. The system operated at 10 µm proved efficiently applicable even to far-infrared detectors.

Low-Temperature Silicon Epitaxial Growth by CO2 Laser CVD Using SiH4 Gas

Silicon epitaxial growth at a low substrate temperature by CO2 laser chemical vapor deposition using SiH4 has been investigated. Single-crystalline Si was grown at a deposition rate of 15 A/s at 650°C under an SiH4 pressure of 0.05 Torr and a CO2 laser power of 6 W/cm2 on an Si substrate. The crystalline quality of deposited Si films was examined by reflection high-energy electron diffraction, and it was found that the deposition rate depends on the incident angle and the polarization of the CO2 laser beam. This is the first report on low-temperature Si epitaxial growth by CO2 laser CVD.

Origin of high-speed modification of refractive index in fused quartz by vacuum ultraviolet laser irradiation

We report on high-speed modification and a large change of the refractive index on the order of 10/sup -2/ of fused quartz upon vacuum ultraviolet (VUV) laser irradiation. The origin of the large refractive index change is discussed based on the laser-induced color center and surface morphology changes. The VUV-UV absorption spectrum of modified samples indicates the formation of a color center at around 163 nm (/spl equiv/Si-Si/spl equiv/defect), which is attributed to bond scission of fused quartz by VUV laser-induced electron excitation. On the other hand, simultaneous UV laser irradiation in our present experimental scheme is responsible for the generation of a surface damage at the large number of pulses, which causes scattering and deterioration of the optical properties of the irradiated regions.

Efficient Amplification of an Optically Pumped NH_3 Laser at 11.707 μm

An output pulse from a line-tunable NH3 laser has been amplified, yielding an energy of about 210 mJ in the 11.707 µm line. The energy conversion efficiency was about 26%. A small signal gain was estimated to be 4.4%/cm.

Difference-Frequency Generation in MgO-Doped Periodically Poled LiNbO3 Using an Electronically Tuned Ti:Sapphire Laser in Dual-Wavelength Operation

Tunable mid-infrared radiation was generated by difference-frequency generation in MgO-doped periodically poled LiNbO3 crystal by mixing of dual-wavelength pulses emitting from a Ti:sapphire laser, which was tuned with an intracavity acousto-optic tunable filter. A tuning range from 3.6 to 5.6 µm was obtained without any mechanical rotation of the nonlinear optical crystal and other laser elements.

Intracavity Difference Frequency Generation Using Dual-wavelength Oscillation by an Electronically Tuned Ti:Sapphire Laser

Tunable mid-infrared radiation was generated by difference frequency mixing in a MgO:LiNbO3 crystal placed in a dual wavelength Ti:sapphire laser controlled with an acousto-optical device. A wavelength range from 2.77 to 5.04 µm was demonstrated by tuning the pump pulse of a longer wavelength in coupling with the rotation of the mixing crystal, while the shorter wavelength pulse was fixed at three selected wavelengths of 703, 711 or 719 nm. The maximum average power was 250 µW and the fluctuation was ±10% at 3.05 µm.