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101.
M. Ramli K. Kagawa S.N. Abdulmadjid N. Idris W.S. Budi M.A. Marpaung K.H. Kurniawan T.J. Lie M.M. Suliyanti R. Hedwig M. Pardede Z.S. Lie M.O. Tjia 《Applied physics. B, Lasers and optics》2007,86(4):729-734
A study of the experimental results on the plasma emissions of water and ethanol vapor samples, induced by Nd:YAG laser in
ambient helium and nitrogen gases at atmospheric pressure, is presented here. The result reveals distinct geometrical and
spectral characteristics of the plasma emissions generated in the helium gas when compared to those observed from nitrogen
gas plasma. Most remarkable is the narrow line width and low continuum background exhibited by emission lines of the analyte
atoms from helium plasma, including the hydrogen emission line which is known to suffer from notorious broadening effects
in conventional laser induced breakdown spectroscopy (LIBS). It is further shown on the basis of the measured spatial distributions
and time profiles of the emission intensities, that the excellent spectral quality is attained by taking advantage of the
meta-stable excited state of helium atoms for the delayed excitation of the hydrogen and other analyte atoms, this allows
the detection of those atomic emissions to be performed under more favorable conditions. The result of this study has thus
demonstrated the feasibility of achieving high-quality spectrochemical analysis, including hydrogen analysis with laser-induced
helium gas breakdown spectroscopy.
PACS 52.38.Mf 相似文献
102.
Zener Sukra Lie Ali Khumaeni Tadashi Maruyama Ken-ichi Fukumoto Hideaki Niki Kiichiro Kagawa 《Applied Physics A: Materials Science & Processing》2010,101(3):555-558
When a Transversely Excited Atmospheric (TEA) CO2 laser (energy of 1.5 J, pulse duration of 200 ns) was focused on a metal sample surface containing hydrogen (H) in He gas
at 1 atm, a strong helium gas plasma was produced and only H atoms came out of the sample. The H atoms then moved into the
helium gas plasma to be excited through meta-stable helium atoms. Using this technique, an excellent linear calibration curve
with zero intercept was made using zircalloy-2 samples containing H (100–600 ppm), where the compensation method was made
using an emission intensity of O I 777.1 nm in order to subtract the H emission intensity coming from unwanted H2O. It should be emphasized that this technique has a possibility to realize highly sensitive analysis of H with a detection
limit of less than 1 ppm because of its selective detection. 相似文献
103.
W. Hardjoutomo H. Munechika H. Kurniawan I. Hattori T. Kobayashi K. Kagawa 《Optics & Laser Technology》1992,24(5)
A compact capacitor-transfer TEA CO2 laser of 180 mJ output energy and 50 ns pulse duration in half width was designed and constructed for field use. This laser is suitable for laser microprobe spectrochemical analysis on geological and mining samples. Experiments show that the use of helium as a surrounding gas suppresses the continuous emission spectrum of the plasma, thus increasing the S/N ratio. Using glass as standard samples, the minimum detectable concentrations are estimated with Zn neutral line and F ionic line to be 60 ppm and 500 ppm, respectively. 相似文献
104.
105.
A carrier protein mediating alanine transport was purified from the membranes of the thermophilic bacterium PS3, by ion exchange chromatography in the presence of both Triton X-100 and urea. The alanine carrier was recovered in the nonadsorbed fraction from either DEAE- or CM-cellulose columns, suggesting that its isoelectric point was in the neutral pH region. The final preparation contained virtually no electron transfer components, ATPase, or NADH dehydrogenase. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the final preparation consisted of two major protein components with molecular weights of 36,000 and 9,400. Active transport of alanine after incorporation of the alanine carrier into reconstituted proteoliposomes was driven not only by an artificial membrane potential generated by potassium ion diffusion via valinomycin but also by mitochondrial cytochrome oxidase incorporated into the same liposomes and supplemented with both cytochrome c and ascorbic acid. The membrane-integrated portion (TFo) of the ATPase complex uncoupled alanine transport by conducting protons across the membrane. 相似文献
106.
Khumaeni A Lie ZS Niki H Kurniawan KH Tjoeng E Lee YI Kurihara K Deguchi Y Kagawa K 《Analytical and bioanalytical chemistry》2011,400(10):3279-3287
A novel method for the direct and sensitive analysis of powder samples has been developed by utilizing the characteristics
of a transversely excited atmospheric (TEA) CO2 laser. In this study, a powder sample was placed in a container and covered by a metal mesh; the metal mesh functions to
control the blowing-off of the powder. The container was then perpendicularly attached on a metal surface. When a TEA CO2 laser (1.5 J, 200 ns) was focused on the metal surface, a large hemispherical gas plasma (radius of around 8 mm) with long
emission lifetime (several tens of microseconds) was produced without ablating the metal surface. The high-speed expansion
force of the gas plasma samples the powder covered by the metal mesh and fine powder particles are sent into the gas plasma
region to be dissociated and excited. Sensitive semi-quantitative analysis was made on organic powder samples such as powdered
rice, starch, seaweed (agar), and supplements. The detection limit of heavy metals of Cr in powdered mineral supplement was
approximately 0.55 mg/kg. 相似文献
107.
108.
109.
Kiichiro Kagawa Mineo Ohtani Sadahiro Yokoi Sadao Nakajima 《Spectrochimica Acta Part B: Atomic Spectroscopy》1984,39(4):525-536
Results are presented of a study on the characteristics of the plasma, namely, the spatial distribution of the emission intensity, the time behavior of the spatial displacement and the excitation temperature, under various conditions of the surrounding gas (pressure range between 0.02 and 6 torr in He, Ar, N2 and CO2). Most of the experimental results can be explained fairly well on the basis of a hypothetical model in which the shock wave plays an important role in forming the luminous plasma. It is found that argon would be most suitable as the surrounding gas when the plasma is used for practical spectrochemical analysis. 相似文献
110.
Shaoshun Li Masayuki Onda Hitoshi Kagawa Hiromi Kawase Mieko Iguchi Yoshihiro Harigaya 《Journal of heterocyclic chemistry》1990,27(7):2029-2035
Solvent effects on the stereochemistry in the sodium borohydride reduction of (±)-flavanonols have been examined. The effects observed for the (±)-flavanonols with 5-OMe in 2-propanol, dioxane and methanol are explainable by the differences between the steric interactions inherent in the product-like transition states A and B. It has been also found that 5-OAc peculiarly affects the stereochemistry in the reduction to produce the (±)-catechin-type compounds in a one-pot process. The solvent and temperature effects are examined using a model analogous to the above. 相似文献