N2 Vapor Research Articles

Surface reflectivity of TiN thin films measured by spectral ellipsometry

Optical properties of TiN thin films have been measured by spectroscopic ellipsometry in the UV-visible range. TiN is a transition metal nitride showing some singular properties such as hardness, wear resistance and golden color, which are very useful in metallurgical and optical coatings. TiN thin films were prepared by plasma enhanced chemical vapor deposition from a gas mixture of N2, H2 and TiCl4 vapor. The properties of TiN thin films mainly depend on deposition conditions and film stoichiometry. In particular, optical properties of TiN thin films can be strongly modulated by technological parameters such as substrate temperature. dilution of gases and RF-power. The reflectivity spectra of TiN films were calculated from ellipsometric measurements and were compared to the evaporated and crystalline gold reflectivity spectra. The reflectivity spectra of TiN films show a shape similar to that of gold, with an edge in the visible region, although the TiN films present lower reflectivity than the gold film.

Synthesis of biomolecules from N2, CO, and H2O by electric discharge

A model primitive gas containing a mixture of N2, CO and water vapor over a water pool (300 mL, ∼ 37 °C) was subjected to electric discharges. The discharge vessel (7 L in volume) was equipped with a CO2 absorber (The CO2 being formed during the discharge), thus simulating possible absorption of CO2 in the primitive ocean. The vessel also has a cold trap (∼ −15 °C), which protects the primary products against the further decomposition in the discharge phase by enabling these products to adhere to the trap. Since the partial pressures of CO and N2 decreased at rates of 1.5–1.7 cmHg day−1 and 0.1–0.2 cmHg day−1, respectively, the gases were added at regular intervals. The solution was analyzed at regular intervals for HCN, HCHO and urea, and maximum concentrations of about 50, 2, and 140 mM were observed. The discharge phase was continued for 6 months. In the solution, glycine (5.6% yield based on the carbon), glycylglycine (0.64%), orotic acid (0.004%) and small amounts of the other amino acids were found.

Excitation of the HgBr B^2Σ1/2+←X^2Σ1/2+ band in the ultraviolet

The buildup and decay of the HgBr X2Σ1/2+ species during a pulsed discharge in Ne, N2, and HgBr2 vapor and in its afterglow have been examined by monitoring B2Σ1/2+←X2Σ1/2+ absorption by the discharge at 351 nm. Also, the UV-to-green conversion efficiency for the 350-nm pumped HgBr laser is shown to be sensitive to the 502-nm fluence circulating in the cavity when the XeF laser pump pulse arrives. The maximum observed efficiency (η) of 22% is obtained for intracavity intensities of 1 to 2 MW/cm2, but η falls to ~10% for I ≃ 1 kW/cm2.

Excited state, charge transfer absorption spectrum of HgBr in the blue (λ∼447 nm)

Absorption from the lowest-lying ion pair state of HgBr (i.e., Hg+–Br−: B 2∑+1/2 ) has been observed by transient absorption spectroscopy in a pulsed, transverse discharge containing a mixture of Ne, N2, and HgBr2 vapor. A highly structured band peaking at ∼447 nm is shown to be associated with charge–transfer transitions from the B 2∑+1/2 state to a higher-lying, covalently bonded (Hg*–Br) state. By pumping the 447 nm transition with a pulsed dye laser while simultaneously monitoring gain on the HgBr (B 2∑+1/2 →X 2∑+1/2 ) band at 502 nm, the absorption cross section for the blue band was measured to be (3.0±1.5)×10−17 cm2 and the saturation intensity for the transition at 447 nm was determined to be 710±50 kW cm−2.

The effects of incorporating water into vacuum-deposited amorphous silicon films

This paper describes the effects on some of the electrical and optical properties of a-Si: C films prepared by vacuum deposition in controlled ambient gases of N2, O2, H2, and water vapour. This stidy was initiated in an attempt to determine the role of a low-energy electron beam irradiating the substrate and film as the layer grows. We find that depositing an a-Si:C film in a water-vapour environment, at a partial pressure of only 4 × 10−8 Torr, will result in the film having a room-temperature resistivity two thousand times higher than that for "clean" films deposited in a good vacuum with a partial pressure of water vapour near 4 × 10−9 Torr (1 Torr = 133.3 Pa). If the partial pressure of the water vapour is increased, the film resistivity increases and it becomes photoconducting. By comparison, the other gases tested had no measurable effect on the properties of the films, with the exception of oxygen which increases the film resistance. None of these latter films were photoconducting. We conclude that the improvement observed in the film properties when samples are irradiated with low-energy electrons results more from the effects of water vapour and (or) oxygen which can be freed from cold surfaces near the substrate than from a possible restructuring of the film as postulated earlier (1).

Investigation of the Gassing Properties of Dielectric Liquids

The gassing properties of some dielectric liquids in the presence of different gases (H2, CO, CO2, N2, O2, CH4, and H2O vapor) have been investigated by means of the experimental apparatus described in IEC 628 specification which measures the oil tendency to emit or absorb gases when it is sub jected to an ionizing electric field. Such tests have been carried out at different temperatures and for different durations. At the end of each test the volume variation of the gas phase has been measured and its composition has been analyzed. Such analyses provided a relevant contribution to the interpretation of the different test results. Further investigation using mass spectroscopy has been started in order to clarify the nature of the products which are found in the oil phase after the test completion; although such a research is still in a preliminary stage, some very stimulating results have already been obtained.

Thermally Stimulated Exoelectron Emission (TSEE) and ESCA Study of Au and Ni Exposed to Ar, O2, N2 and C2H5OH Vapor Plasmas

The interactions of Au with Ar and O2 plasmas, and of Ni with O2, N2 and C2H5OH vapor plasmas have been studied by TSEE and XPS. The TSEE was strongly influenced by the amount of oxygen incorporated at metal surfaces due to the effects of the plasmas, and was suppressed by the oxygen incorporated in excess. With Au samples, Ar plasma produced a TSEE peak at about 170°C and O2 plasma two peaks at about 180–190°C and 120°C; O2 plasma gave a much weaker emission than the Ar plasma. Au samples exposed to the plasmas gave XPS spectra of Au, C, O, Al and Si. The incorporation of Si and Al may be attributable to the plasma reactor. The TSEE was closely correlated with the composition ratio of O/Si, resulting in a maximum at the value of O/Si=0.4. With Ni samples, a TSEE peak appeared at about 177°C independently of the plasma atmospheres. The peak intensity was satisfactorily correlated with the ratios of O/Ni and O/C, giving a maximum at the values of O/Ni=8 and O/C=1.

Skin gas tensions and resistances measured by mass spectrometry in adults.

We used a dual-sampling chamber 2.5 cm in diameter, controlled by an Apple II microcomputer, to measure gas tensions in the skin of adults by mass spectrometry. The tensions of O2, CO2, N2, and water vapor and the resistances to the flows of gases through the skin were calculated from the voltages for the different gases passing through two separate membranes of different permeability. We compared the skin O2 and CO2 tensions with arterial values in 13 patients with lung disease during a standardized exercise test. The skin values followed changes in the arterial values. The regression line relating skin to arterial O2 tension had a slope of 1.05 and that for CO2 a slope of 1.51. We conclude that mass spectrometry is capable of providing measurements of gas tension from the heated skin that are similar to those found using electrochemical methods in adults.

Influence of cooling rates and extenders upon post-thaw viability of bovine spermatozoa packaged in .25- and .5-ml French straws.

Post-thaw survival of bovine spermatozoa was compared for semen packaged in either .25- or .5-ml French straws and frozen at three different cooling rates in moving N2 vapor. Using a split ejaculate technique, nine ejaculates were extended in heated skim milk, egg yolk-citrate and egg yolk-Tris and packaged in .25- and .5-ml French straws. Semen packaged in the .25- and .5-ml straws was frozen simultaneously at initial N2 vapor temperatures of -140, -110 or -80 C. Semen was thawed in a water bath at 35 C for 1 min. Recovery of spermatozoa was evaluated immediately post-thaw (0 h) and again after 3 h of incubation at 37 C. Motility estimates and motility counts were made using phase contrast microscopy; percentage of spermatozoa possessing intact acrosomes was quantitated using differential interference contrast microscopy. There was a packaging unit X cooling rate interaction (P less than .05) for all three viability measures. However, there was no consistent trend with regard to cooling rate or packaging unit among the three extenders examined. Post-thaw viability for each characteristic varied (P less than .01) among extenders, but not for cooling rate or packaging unit (P greater than .05). Spermatozoa extended and frozen in egg yolk-Tris had greater (P less than .05) post-thaw viability than those extended in skim milk or egg yolk-citrate regardless of cooling rate or volume of the seminal package.

Enhanced HgBr(B2Σ+→X 2Σ+) emission at low pressures

Additives of N2 and I2 vapor in diffuse HgBr2 discharges have been observed to produce a large enhancement of radiated power due to B2Σ+→X2Σ+ transitions at low pressures. The integrated power in the spectral range between 374 and 543 nm was recorded by means of an optical multichannel analyzer system. Optimization of the B→X radiation was investigated, and absolute efficiency was determined over a range of ‖E‖/N.

Sintering of Ultrafine Metal Powders. II. Neck Growth Stage of Au, Ag, Al and Cu

The neck growth stage in the sintering of ultrafine powders of Au, Ag, Al and Cu has been studied by electrical resistance measurement and electron microscopy. A formula for the electrical resistance at the necks of ultrafine metal powders is proposed. The decrease in the resistance of powders isothermally annealed at room temperature without compacting is explained as the neck growth among powders due to surface diffusion. The activation energy for the surface diffusion of Au is found to be 0.88±0.02 eV from resistance measurements. Obstruction of the neck growth is clearly detected in an atmosphere of O2 in all the materials examined, whereas obstruction by N2, Ar and aqueous vapour is found to be negligible compared with that of O2.

Model experiments on nitrite and nitrate in simulated primeval conditions.

In experiments on the prebiotic formation of nitric oxides, anoxic mixtures of N2 and water vapour were sparked in contact with phosphate buffer solutions at various pH values. Nitrite was found in the aqueous phase, and nitrate grew from it, presumably by reaction with H2O2. In acid solutions, these anions were reduced and destroyed by Fe2+, and the same was true of nitrite in solutions kept at a pH value similar to that of the contemporary ocean (8.2) with HEPES buffer. Nitrate was not destroyed in short-term experiments, but as in sparking nitrate is formed only vianitrite, neither anion could accumulate. In further sparking experiments with alkaline sulphide, both nitrite and nitrate were reduced entirely. It is concluded that it is unlikely that the primeval ocean contained appreciable concentrations of nitrite or nitrate either at the reducing or at the redox-neutral stage.

Intense laser emission from electron-beam-pumped ternary mixtures of Ar, N2, and POPOP vapor

Powerful laser output was observed at 381 nm from electron-beam-pumped ternary mixtures of argon-nitrogen and 2,2′-p-phenylinebis(5-phenyloxazole) (POPOP) dye vapor. The injection of the subthreshold 380.5-nm N2 line into the electrically excited gain profile of POPOP vapor has been identified as a pumping mechanism.

Pore Structure of Calcium Silicate Hydrate in Hydrated Tricalcium Silicate

Adsorption of N2 and water vapor was studied in completely hydrated tricalcium silicate and in fully hydrated tricalcium silicate from which Ca(OH)2 had been extracted. Compared with results obtained using N2, water vapor adsorption led to increased values for small‐pore volume, peak shifts to smaller sizes, and decreased values for large‐pore volume. Marked hysteresis was observed in the case of water vapor adsorption; the resorption branch apparently represents the true pore structure. Extraction of Ca(OH)2 from the paste increased the calculated volume of small pores strikingly, suggesting that adsorption is hindered by Ca(OH)2; this tendency is more obvious in water vapor adsorption. The adsorption measurements indicate the existence of two kinds of pores, i.e. a wider intergel‐particle pore and a smaller pore existing within the gel particle. The latter pore was further classified into intercrystallite and intracrystallite pores.

Gas embolism due to intravenous FC 80 liquid fluorocarbon.

Lethal gas embolism always occurs after FC 80 liquid fluorocarbon is injected intravenously (0.1 ml/kg body mass) in dogs breathing room air but not in dogs breathing oxygenated FC 80 liquid fluorocarbon. Gas embolism is not prevented in dogs that have been injected intravenously with FC 80 when they are exposed to 2 ATA (atmospheres absolute) 20% 02-80% N2, 9 ATA 5% O2-95% He, or 1 ATA 100%, O2. In dogs that die of FC 80-induced gas embolism, free gas in the right atrium contains approximately 0.5 g FC 80/liter, and Po2 and Pco2 in the gas are in equilibrium with their corresponding tensions in right atrial blood. These observations are consistent with the hypothesis that PFC 80 in alveolar gas does not equilibrate with PFC 80 (55 mmHg) in blood. The total gas tension in pulmonary capillary blood containing FC 80 and its vapor thus exceeds the total tension of alveolar gases (atmospheric pressure). Bubbles of O2, CO2, N2, FC 80, and water vapor form in the regions of the pulmonary capillary bed where the total tension of gases dissolved in blood exceeds the absolute blood pressure.

Changes in the Physical Properties of Soil Clays Due to Precipitated Aluminum and Iron Hydroxides: I. Swelling and Aggregate Stability After Drying

AbstractCompressed discs of an illite, a kaolinite, and a mixture of the two were formed from freeze‐dried dispersed suspensions of the clays, into which one level of Fe(OH)3 and two levels of Al(OH)3 had been precipitated. The precipitated Fe was found to consist of particles about 40Å in diameter and amorphous to X‐ray, rather than the acicular goethite that precipitates under similar conditions in the absence of clay. It was deduced from N2 and water vapor sorption measurements that the precipitated Al was present as very thin layers on the surface of the clay particles, which in the case of the illite could bridge some of the particles. Their form was generally indeterminate, in contrast to the well‐crystallized bayerite formed in the absence of clay.All three hydroxy treatments inhibited the double‐layer swelling of the Na‐illite and Na‐kaolinite/illite mixture in dilute NaCl solutions. Both on weight percent and on an equimolar basis, Al was more effective than Fe in reducing the slaking of dry clay discs and in increasing the resistance of clay to dispersion in pyrophosphate solutions. Possible bonding mechanisms between the precipitate and the clays are discussed.

Exchange of SO2 between the Atmosphere and Natural Waters

LITTLE is known about the rate of exchange of gas between the atmosphere and natural waters (such as oceans, rivers, lakes and airborne water droplets), and most work so far has concentrated on the more common atmospheric constituents, N2, O2, CO2 and water vapour. The transfer of trace components, such as oxides of sulphur and nitrogen, has received almost no attention. This article is an attempt to predict the principal factors controlling the exchange of SO2 across air–water interfaces in the natural environment.

The reduction of barytes with hydrogen. I. Kinetic studies in a differential reactor

AbstractThe reduction of barytes by H2 has been studied at 800°, 900°, 1000° and 1100° in a differential reactor. The reaction rate is markedly temperature‐dependent; it is accelerated by the presence of iron and siliceous impurities in the barytes, but is relatively insensitive to variations in the partial pressure of H2 due to the presence of N2 or water vapour. The available evidence suggests that the rate of reduction is chemically controlled and that the reaction occurring at the BaSO4‐BaS interface depends upon the presence of defects in the BaSO4 lattice. An empirical equation is developed for the experimental rate data at 1100°, use of which may be of value in design work.