Infrared Absorption Method Research Articles

A new direct infrared laser absorption method for state-to-state rotational energy transfer in crossed supersonic jets: Experimental results and quantum scattering analysis for Ar+CH4

A new method for measuring state-to-state rotational energy transfer in crossed supersonic beams is described. The method is based on direct absorption of tunable, high-resolution infrared laser light by target molecules collisionally excited into final rotational states. The direct IR absorption approach offers high sensitivity, full quantum state resolution, a Doppler probe of final velocity components, and is applicable to any target molecule that absorbs in the near IR. Preliminary results are presented for Ar+CH4 scattering in crossed supersonic beams at a mean center-of-mass collision energy of 41 meV. Because of the high spectral resolution, the method can readily distinguish rotational fine structure states of A, F, and E symmetry in the tetrahedral group, as well as the much more energetically separated final j states. The results are compared with full quantum close-coupling calculations on two different Ar+CH4 potential energy surfaces. The state-to-state scattering results provide a sensitive measure of the potential anisotropy, and in particular probe the relative magnitudes of the different anisotropic terms in the potential (V3 and V4).

A Study on Concentration Field of Unsteady Gaseous Fuel Jet. Axisymmetric Turbulent Free Methane Jet.

Fuel gas injection is used for gas diesel engines. It is very important to investigate the behaviour of the unsteady jet. In this study, the concentration field of a suddenly started cold methane gas jet into still air was nonintrusively measured by the infrared absorption method with a 3.39μm He-Ne laser. Furthermome, the equations of mass, momentum, energy, species (methane and air) and the k-ε turbulence model were solved numerically. The concentration field was obtained and compared with the experimental results. As a result, it was found that the global trends of the jet, that is to say, penetration and averaged concentration, are predicted well, though the unsteady concentration near the jet axis is not predicted because the turbulence model is based on the time-averaged one.

不活性ガス融解赤外線吸収法による高純度鉄中の極微量酸素定量

不活性ガス融解赤外線吸収法による高純度鉄中の極微量酸素定量

Phase Equilibrium in Y–Ba–O System

In order to make clear the phase equilibrium in the Y-Ba-O system, the samples were prepared using the raw materials of Y 2 O 3 and BaCO 3 or BaO 2 in natural air or in mixed gas of 21%O 2 +Ar, respectively. The phase relation was investigated using X-ray diffraction and EPMA methods. The carbon content was measured by means of oxygen combustion infrared absorption method. From the experimental results, the isobaric sections of the Y-Ba-O system were evaluated

Study of the thermal/oxidation degradation of the sodium-cellulose sulphate half-ester

The thermostability off a sodium-cellulose sulphate half-ester (NaCS) in dilute solution at 80°C has been investigated by means of electric conductance titrimetry, colloid titrimetry, viscosimetric methods and by the infra-red absorption method. From the dependence of relative viscosity upon time, the main parameters affecting the thermal degradation of NaCS aqueous solution were pH, added salt and antioxidant. It was found that (1) 500 ppm of added KI can effectively suppress the oxidative scission of the glucoside linkage and the retention (R %) of relative viscosity was more than 80% after 180 days' ageing at 80°C; (2) the quantity of −OSO 3 − groups remained unchanged during the long term of ageing. Derived kinetic data, which agreed with the experimental results, indicate that the thermal oxidation degradation of aqueous solution of NaCs at 80°C proceeds by random scission of the main chain. A degradation mechanism has been developed using these observations.

New method to determine the carbon concentration in silicon

Silicon samples subjected to a CF4 reactive ion etch exhibit the G-line luminescence known from photoluminescence studies of irradiation damage in Si. We investigate the mechanism of low-energy carbon implantation by CF4 plasma and find a linear dependence of the G-line luminescence intensity on the substitutional carbon concentration in the samples. By a standardized etching and photoluminescence procedure, we expect to determine carbon concentrations two orders of magnitude smaller than the ASTM infrared absorption method.

Linear oligopeptides. 99. An infrared absorption method to titrate quantitatively the extent of self-association in peptides

Linear oligopeptides. 99. An infrared absorption method to titrate quantitatively the extent of self-association in peptides

78 K infrared absorption method for measuring the oxygen content in silicon

A more accurate calibration curve at 78 K for measuring the oxygen content in silicon single crystals has been established by the infrared absorption difference method. The resulting formula is N O = 2.6 α ppmA, or N O = 1.3 × 10 17 α atoms/cm 3 where α represents the IR absorption coefficient.

Direct observation of the principal deep level (EL2) in undoped semi-insulating GaAs

A high spatial resolution, near infrared absorption method has been used to determine [EL2] concentrations in semi-insulating undoped Czochralski liquid encapsulated (LEC) GaAs. Fine structure superimposed on the well-known ‘‘W’’ distribution across 〈110〉 diameters of {001} wafers has been detected. Fine structure has also been directly observed in {110} sections of ingots grown along 〈001〉 using a CCTV vidicon system to observe transmitted infrared radiation. The structure consists of narrow bands of increased absorption which correspond with high densities of dislocations in the same specimens.

Infrared analysis of the grossular-hydrogrossular series.

The infrared absorption spectra of the grossular–hydrogrossular series have been recorded for hydrothermally synthesized materials. The compositions of the prepared materials are Ca3Al2(SiO4)3−x(O4H4)x (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0). Infrared absorption patterns of these garnets were given by the KBr method in the range of wave number from 4000 cm−1 to 250 cm−1 after drying in a vacuum desiccator with Mg(ClO4)2. The results showed a close relation between the spectrum patterns and the amounts of constitutional water in these garnets. The linear relation between the chemical composition and the ratio of logarithmic transmittancy, was observed for 14 pairs of absorption bands and/or transmission ones. This implies the possible use of the infrared absorption method in the determination of the amount of water in garnets of this series.

Self-association and solubility of peptides. An infrared absorption method for quantitative titration of the extent of self-association in poly(ethylene glycol)-bound peptides

The disruption of the sparingly soluble, self-associated species (β-structure) of the polymer-bound, N-protected peptides Boc-L-Ala-Gly-L-lle-(L-Ala)2-NHPEG and Boc-(L-Ala)2-Gly-L-lle-(L-Ala)2-NHPEG [PEG = poly(ethylene glycol)] in methylene chloride by increasing amounts of N,N-dimethylformamide or dimethyl sulphoxide has been monitored by following the disappearance of the intense amide I or A i.r. bands of the strongly intermolecularly hydrogen-bonded molecules; this suggests the use of this method for the quantitative titration of the extent of self-association in PEG-bound peptides.

Oxygen Precipitation Factors in Silicon

To clarify the oxygen precipitation factors in silicon crystals, the oxygen precipitation behavior according to heat‐treatments in a whole Czochralski‐grown silicon ingot, from the seed end to bottom end, is examined using the infrared absorption method and TEM. Comparison of results shows that oxygen precipitation (i) strongly depends on the initial oxygen concentration , (ii) rarely occurs in wafers with less than , (iii) proceeds most rapidly during the annealing at 1000°C, and (iv) is contingent on the specimen position in the crystal ingot. The results of (iii) and (iv) are supported by TEM observation, which reveals the densest dislocations in the specimen annealed at 1000°C and the difference in oxygen precipitates between the specimens with the same but taken from different positions in an ingot.

Defects in silicon crystals after the high temperature treatment

The defect formation process in dislocation free Czochralski silicon crystals after annealing at 1000 °C is studied by infrared absorption method, X-ray topography, and transmission electron microscopy. Crystals: as-grown, preliminary treated at 700 °C for 2 h or irradiated with fast pile neutrons (Φ ≈ 1019 neutrons/cm2) are used for investigations. Evidence is obtained concerning the generation and evolution of defects. Correlation between the defect concentration and the changing of interstitial oxygen content in silicon crystals is established. The oxygen precipitation process is shown to be accelerated essentially in fast pile neutrons irradiated crystals. [Russian Text Ignored]

Determination of oxygen with reactor neutrons

Oxygen in silicon was determined by the secondary nuclear reactions of6Li(n, α)T and16O(t, n)18F. Lithium fluoride was deposited in vacuum on fused quartz, covered with the sample and irradiated in a nuclear reactor. The depth profiles of18F in fused quartz and in silicon were observed, and enough depth to eliminate surface oxygen was estimated. On the basis of these results, oxygen was determined by the average cross-section method. Oxygen concentration in CZ silicon with various growing condition was 5–26 ppm and was consistent with those determined by the infrared absorption method. The detection limit of oxygen in silicon is 5 ppm.

Microdefects distribution in Czochralski-grown silicon crystals

Striated microdefect distribution (swirl defects) are formed by the heat treatment in Czochralski-grown silicon crystals. The striation observed by etching has two period components 1–2 mm and 300–500 μm along growth direction. The corresponding microdistribution of oxygen was examined by the scanning infrared absorption method with the collimated beam of 100 μm in diameter. The results show that the distribution with the period of 1–2 mm was only observed, but not the microdistribution with the period of 300–500 μm. It is proposed from the results that microdefects are originated at a high oxygen-concentration region from the nuclei which were introduced in a striated pattern with the period of 300–500 μm during crystal growth. The nucleus is not interstitial oxygen itself.

Observation of the Infrared Spectrum ofH3+

The infrared ${\ensuremath{\nu}}_{2}$ band of ${\mathrm{H}}_{3}^{+}$ has been observed. A direct infrared absorption method combining a liquid-nitrogen-cooled multiple-reflection discharge cell and a difference-frequency laser system has been used for the detection. Fifteen absorption lines have been measured in the region of 2950-2450 ${\mathrm{cm}}^{\ensuremath{-}1}$ and assigned. This is the first spectroscopic detection of this fundamental molecular ion in any spectral range.

Dielectric behaviour of nylon 6

Dielectric measurements over a frequency band from 0.2 to 10 MHz were first made on dry samples of nylon 6 of different particle size under vacuum at temperatures from 10 to 70 °C, and then on various humid samples at 25 °C.The dependence of the dielectric constant on particle size was related to the crystallinity degree of the sample, which was determined by the infrared absorption method. Two relaxation effects were detected in the dry state, the magnitudes of which increased with decrease of particle size thus indicating that they originated in the non-crystalline regions of the polymer.One relaxation process with a large distribution of relaxation times appeared below the glass transition temperature, and the other appeared above. The former was suggested to ne to a Maxwell-Wagner effect arising from the inhomogeneity of the sample together with some dipole relaxations (β) Motions of the dipoles CO and NH groups in the non-crystal- were possible. The latter relaxation (α) was attributed to co-operative motions in the main chains of these regions.As regards the effect of humidity on the dielectric behaviour of nylon 6, it was suggested that the water molecules were first involved in hygroden-bond formation, and finally a conduction network similar to that of ice was produced.

Determination of oil in waste water by infrared absorption method

Determination of oil in waste water by infrared absorption method

Infra-red heterodyne laser radar for remote sensing of air pollutants by range-resolved differential absorption

An infra-red heterodyne laser radar scheme incorporating range-resolved differential absorption using elastically backscattered, pulsed signal from distributed particles in the atmosphere is proposed and analysed. The basic requirements of the system arrangement and operating parameters involved in this scheme are discussed in detail. This method is shown to offer a remote and spatially-resolved measurement of various molecuar pollutants dispersed in the air for ranges up to several km and detection sensitivities to less than 0.1 ppm with laser pulses of 100 W average power. This power is 103 to 106 times smaller than that required with the conventional direct detection technique in the infra-red. The measuring accuracy and its limiting processes inherent to the infra-red range-resolved differential absorption method are also analysed.

The Determination of HF, HCl, SiF4, and HCF3 in WF6 Gas

An infrared absorption method in the 1- to 15-µ range has been developed for determining HF, HCl, HCF3, and SiF4 in WF6, gas. Because of the reactivity and corrosiveness of WF6, a special gas absorption cell and gas-sampling apparatus were designed and built. Calibration curves were generated for a 10-cm cell. Sensitivity values were 100 wppm for HF and HCl, and 10 wppm for HCF3 and SiF4.