bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen in Silicon
Authors: Kaiser W. , Thurmond C. D. 
Published: April 2005

Liquid silicon has been exposed to gaseous ambients containing varying concentrations of N2 or NH3. Under certain conditions, Si3N4 needles may be grown on the surface and into the body of the melt. The molten zone of silicon was supported between two rods of solid silicon. We have found that the concentration of nitrogen in molten silicon which is saturated with respect to silicon nitride at a temperature near the melting point of silicon is around 1019 atoms per cm3. During the freezing of the melt, Si3N4 precipitates from the supersaturated liquid phase.
The concentration of electrically active impurity states in silicon grown from melts containing around 1019 atoms per cm3 of nitrogen is less than 1012 atoms per cm3.
Structure of Quenched and Irradiated Metals
Authors: Smallman R. E. , Westmacott K. H. 
Published: April 2005

The effect of introducing point defects into pure metals by (a) quenching and (b) irradiation has been studied using the small-angle x-ray scatter technique. Scattering was obtained from both quenched copper and aluminum after appropriate ageing treatments, from α-irradiated copper after annealing, and from neutron-irradiated copper. The source of scattering has been considered in each case.
Direct observation of the scattering defects has been obtained for the quenched, neutron-, and α-irradiated metals using thin film electron transmission microscopy. The quenched copper and aluminum contain dislocation loops of the order of a few hundred angstroms diameter formed by the condensation of vacancies, while the α-irradiated metal contains small cavities. Some additional electron microscopic studies of quenched silver and gold are also mentioned and the results discussed in relation to the mechanical and physical properties of quenched metals. No direct evidence has yet been found in neutron-irradiated copper (because of the difficulties in electropolishing), but the small-angle scattering when considered with mechanical property measurements strongly suggests the existence of small ``regions'' ∼100 A diameter. Direct observation of ``damage'' in neutron-irradiated aluminium is observed, however, and shows the existence of dislocation loops, ``jogged'' dislocations, and ``spiral'' dislocations in agreement with theoretical predictions.
Experimental Verification of Theoretical Relations between Total Gas Absorptivities and Total Gas Emissivities for CO
Authors: Oppenheim U. P. 
Published: April 2005

An experimental study has been carried out for the purpose of verifying theoretical predictions concerning the relations between total absorptivities and total emissivities for transparent gases. The experimental conditions have been designed in such a way as to permit a direct check of theoretical relations derived for (a) nonoverlapping dispersion lines and (b) spectral lines with sufficient pressure broadening to permit neglect of the rotational fine structure. A comparison between the emissivities derived from absorptivity measurements and emissivities calculated from the spectroscopic constants of CO shows a good agreement (within 20% for most of the temperature range).
The apparatus for the measurement of total gas absorptivities is described. Results for total absorptivities of carbon monoxide measured at temperatures between 300 and 500°K are given and total emissivities have been calculated in the temperature range of 300 to 1600°K. The range of total gas pressure is 0 to 515 psia.
Magnetic and Electrical Properties of Reactor-Irradiated Silicon
Authors: Sonder E. 
Published: April 2005

Magnetic susceptibility measurements above 3°K and Hall effect and resistivity determinations between 50 and 300°K are reported for n-type silicon samples irradiated with increasingly higher doses of fission neutrons. The paramagnetism due to electronic states in the forbidden gap shows an initial decrease after short irradiation but a reversal, increase, and final saturation at a value less than that originally contributed to the paramagnetism by the filled donors after longer irradiation.
The Hall coefficient shows evidence of a distribution of irradiation-produced energy levels in the neighborhood of 0.3 ev below the conduction band. The mobility goes through an initial sharp decrease with irradiation but recovers partially after longer irradiations. The results are discussed in terms of several models of radiation damage. It is concluded that a simple model based on uniformly dispersed interstitials and vacancies is not adequate to explain the results and that interactions between centers, and nonuniform distribution of damage will probably have to be taken into consideration.
Harmonic Current Growth in Velocity-Modulated Electron Beams
Authors: Mihran T. G. 
Published: April 2005

Harmonic currents accompanying a fundamental space charge wave of current in a velocity modulated electron beam are found to grow with distance even though the peak amplitude of the fundamental current remains relatively constant.
This effect was first noted in studying the results of a series of disk-electron calculations. Subsequently, second harmonic growth was found experimentally using a sliding cavity setup. A physical explanation of this phenomenon is given.
The harmonic growth can be interpreted as parametric amplification in which the finite electron beam acts as the nonlinear element, with the fundamental current providing the pump power.
Nuclear Magnetic Resonance Studies of Dislocations in NaI and KI
Authors: Hon J. F. , Bray P. J. 
Published: April 2005

Intensity anomalies have been found in the nuclear magnetic resonance of I127 in NaI and KI single crystals when the magnetic field is along a [1,0,0] type direction. The intensity enhancement in these cases indicates a collapse of the satellite transitions (m → m − 1, m ≠ ½) into the central transition (m = ½ → m = −½). It is concluded that the crystals contain edge and/or screw dislocations which are preferentially oriented along [1,1,0] and [1,0,0] type directions, respectively. The degree of orientation is greater in NaI than in KI.
These studies afford an explanation of anomalous resonance line widths reported for NaI by other observers.
Vapor Phase Growth and Properties of Zinc Sulfide Single Crystals
Authors: Samelson Harold 
Published: April 2005

The growth of zinc sulfide single crystals by a sealed tube vapor phase method is described. In this system the parameters that are studied are the evaporation temperature, the temperature schedule during a run, the temperature gradient along the length of the tube, and, finally, the ambient pressure of H2S in the tube. The resulting crystals are of a rodlike, distorted rodlike, or platelike habit, and the dominant habit, in any given run, is responsive to variations in the experimental parameters. An altogether different habit is observed in runs performed in a vacuum. The structure of the crystals varies from pure hexagonal to reversed cubic; most of the crystals exhibit stacking faults to various degrees. The structure is a function of the growth temperature.
For crystals grown in an H2S ambient, the mechanism proposed is an initial growth of a fine rod followed by a thickening of the rod and its possible subsequent development into a plate. The whisker growth is probably not a nucleation process and may proceed by a screw dislocation or stepped plane mechanism. The subsequent steps, as well as the growth of crystals in a vacuum are consistent with a surface nucleation mechanism.
Shock-Wave Compression of Iron and Bismuth
Authors: Hughes D. S. , Gourley L. E. , Gourley Mary F. 
Published: April 2005

A helium gun was used to propel metal projectiles against targets of the same materials. Pressures produced by impact were varied by varying projectile velocities. The method produced pressures up to somewhat over 100 kbar, thus overlapping the lower part of the range of pressures which can be produced by detonation of high explosives. Of particular interest was the range of pressures intermediate between the highest which can be produced statically and the lowest which can be produced by explosives.
A condenser micrometer was used to detect motion of the free surface of the target. This method permitted examination of the motion in greater detail than could reasonably be accomplished by other methods which have been used. Elastic and plastic waves were observed in iron and in bismuth. Assuming the Rankine-Hugoniot shock conditions, pressures and compressions were computed. Pressure-compression data for iron were obtained for intermediate pressures not previously investigated. Phase transitions in bismuth were observed for pressures up to about 40 kbar.
Spectroscopic Studies of Rotational Isomerism in Fluorinated Ethanes. II. 1,2-Dibromo-1,1,2,2-Tetrafluoroethane
Authors: Kagarise R. E. , Daasch L. W. 
Published: April 2005

The Raman spectrum of liquid CF2Br–CF2Br has been investigated, and the observed frequency shifts (Δν cm—1), relative intensities and depolarization factors are presented. The infrared absorption spectrum of the liquid in the 2—34μ region, and of the solid and vapor in the 2—22μ region have also been studied.
On the basis of observations of the Raman spectrum of the liquid and the infrared spectrum of the vapor, liquid, and solid it is concluded that CF2Br–CF2Br exists as two isomeric species. Of these, the trans-form (C2H) is the more stable, while the gauche-(C2) is probably the higher energy form. The value of ΔH° for the reaction trans-(C2H) ← gauche-(C2) was found to be 925±50 calories/mole in the liquid and 945±50 calories/mole in the vapor state.
Electrochemical Polarization in Isopropyl Ether
Authors: Rider John A. 
Published: April 2005

Measurements have been made of the polarization effects in electrical conduction through isopropyl ether. This liquid was chosen because its conductivity is intermediate between that of dielectric liquids and water. Correlation of experimental results in this range with the Jaffé theory had not heretofore been checked. The present results provide a bridge across the gap which formerly existed in polarization measurements between conductivities of 10—6 ohm—1 cm—1 and 10—18 ohm—1 cm—1.
Observations were made of the time dependence of current following the application of various voltages to the electrodes of a cell containing the liquid.
Measurements in the present range broaden the pattern of agreement of the Jaffé theory with experiment. Such agreement now extends from semiconductors and aqueous solutions to dielectric liquids. In all cases good quantitative agreement is obtained provided part of the conductance is attributed to carriers of considerably lower mobility than the ordinary conductivity carriers.
Transformation of Adsorbed Water on Solid Surfaces and its Dielectric Losses and Conductivities
Authors: Kurosaki Shigehiko , Saitō Shōgo , Satō Genju 
Published: April 2005

The adsorption isotherm of water vapor on nonalkali glass cloth was obtained at 25°C, and its dielectric power factor was measured also in the frequency range of 80 kc/sec∼11 mc/sec.
The power factor of glass cloth and surface dc conductivities of nonalkali glass, soda glass, fused silica, Teflon, and polymethylmethacrylate plates increased rapidly to maximum peaks, when they were exposed to water vapor, and then gradually decreased to certain constant values.
These phenomena may be interpreted as physical picture of phase changes in the adsorbed water phase from the amorphous state to the crystalline state, as well as the deposit films of evaporated metals on solid surfaces. But the surface conductivity of polycapramide increases as the moisture content increases with time, suggesting a rapid absorption of water molecules into the solid. An analysis of this process of phase change of adsorbed water is outlined.
Effects of Oxygen on PbS Films
Authors: Minden Henry T. 
Published: April 2005

The effect of oxygen on the conductivity of vacuum evaporated PbS films has been experimentally investigated. When outgassed these films are n-type semiconductors. If they are exposed to oxygen at temperatures below about 200°C, the conductivity decreases with increasing pressure and then increases again. The thermoelectric power changes from negative to positive, but less than 10—3 moleO2/molePbS is sorbed by the film.
Above 200°C the conductivity merely decreases when oxygen is admitted, and the thermoelectric power becomes small. The film gradually absorbs all the oxygen in the vacuum system and evolves a good deal of SO2. When the reaction is complete, the conductivity returns to its initial value, and the thermoelectric power is once again negative. The film can repeatedly absorb large amounts of oxygen without there being any permanent change in electrical properties.
It is concluded that these films are composed of two layers. Next to the substrate there is a conducting layer that chemisorbs oxygen but does not react with it. The chemisorbed oxygen acceptors are responsible for the observed changes in conductivity. The upper layer of the film is nonconducting and reacts to completion with oxygen, possibly forming PbSO3:PbO, and evolving SO2.
π-Electronic Structure of the HCN Molecule
Authors: Iguchi Kaoru 
Published: April 2005

The HCN molecule is treated as a system of four π electrons moving in a suitable potential field. Its lower excited states are calculated, using both the molecular orbital method with configuration interaction and the Heitler-London method including ionic-homopolar resonance.
Slater atomic orbitals with effective charges 2δ=3.18 for the C atom and 3.85 for the N atom are employed.
The calculated energy levels with the 1Σ+ ground state as zero are 3.53 ev (3Σ+), 5.60 ev (1Σ—), 7.71 ev (3Δ), etc. The effect of configuration interaction is remarkable, amounting to several electron volts, and ionic terms have almost the same weight as homopolar terms.
Pyrolysis of Acetone and the Heat of Formation of Acetyl Radicals
Authors: Szwarc M. , Taylor J. Watson 
Published: April 2005

Pyrolysis of acetone in the presence of an excess of toluene has been studied. The rate of the decomposition has been followed by the rate of formation of CO, the following sequence of reactions being assumed: CH3·CO·CH3→CH3+CO·CH3  slowCH3·CO→CH3+CO  fastThe reactions seem to be first order and unimolecular, the rate constant of the first step being determined as k=2.4·1014 exp (—72 000/RT) sec—1. It is assumed that the observed activation energy may be identified with CH3·CO–CH3 bond dissociation energy and on this basis the heat of formation of acetyl radical is calculated at — 10.8 kcal/mole.
The last result is compared with the findings resulting from investigation of the pyrolyses of diacetyl and of benzyl methyl ketone.
The validity of the toluene carrier technique is reviewed.
Experiments on the Carnauba Wax Electret
Authors: Gerson Robert , Rohrbaugh J. H. 
Published: April 2005

The strength of the applied electric field, the thickness of the slab being electrified, the time of electrification and the low temperature holding time before removing the field were varied for carnauba wax electrets. After approximately one hour the discharge current varied inversely as a power of the time since turning off the forming field, the power being close to one. The magnitude of this current depended on both the forming field strength and on the thickness of the electret. A very large discharge was obtained when the wax was electrified and discharged while not completely solid.
Dielectric constant measurements were made at temperatures between 27°C and 86°C, frequencies between 50 cps and 13 kc, and with superposed dc field strengths in the wax of zero, 3700 and 8100 volts per cm. The application of dc field was found to raise the dielectric constant at the higher temperatures.
The case for permanent dipole orientation and that for ionic space charges as the cause of the stored charge of the electret is examined, and it is shown that there are objections to each mechanism. An alternate explanation is suggested.
Relative Diameter of Oxygen and Hydrogen Molecules, using Negative Pressure as an Indicator
Authors: Briggs Lyman J. 
Published: April 2005

A vertical glass tube (1 cm bore and about 100 cm long) carries at its closed upper end two opposed spherical platinum electrodes, approximately 1 and 2 mm in diameter. The lower end of the tube is bent upward in the form of a J, to which is attached a cylindrical reservoir. After introducing sufficient electrolyte (1NH2SO4) to more than fill the long tube, the system is evacuated and sealed off.
On rotating the long tube from an inverted to a vertical position, the column of liquid remains hanging from the top of the tube, under a negative pressure (at the top), equal to the length of the column down to the meniscus, times its density, less the vapor pressure in the reservoir. The minimum electric charge required to drop the column is determined by successive trials, using a mica capacitor (adjustable in steps of 0.001 μf), which is first charged to a known potential and then connected to the electrodes through a quick-acting switch. After each drop of the column, the polarity is reversed. Hydrogen is deposited as an incomplete monomolecular film when the smaller test electrode is the cathode; oxygen, when it is the anode.
The critical anodic charge was divided by 2, oxygen being bivalent. The ratio of the critical charges gives the relative number of molecules involved; and its reciprocal, the ratio of the projected areas. The mean of 9 series of measurements gave 1.022±0.006 as the ratio of the diameter of the oxygen to the hydrogen molecule. Measurements by other methods range from 1.54 to 0.89.
A Theory of Thermal Diffusion in Liquids
Authors: Dougherty E. L. , Drickamer H. G. 
Published: April 2005

A theory of thermal diffusion in liquids has been developed based on Denbigh's interpretation of the ``net heat of transport'' which arises in the thermodynamics of irreversible processes. The thermal diffusion ratio α is expressed in terms of the energies of vaporization of the pure components, the excess energy, entropy and volume of mixing, and the concentration dependence of ΔUc. The efficiency with which the two species pack together is also introduced. The Hildebrand-Scatchard solution theory is applied to these results and α is expressed in terms of solubility parameters, molal volumes and packing efficiencies.
The equations are compared with previously published experimental results, and reasonably explainable packing efficiencies are obtained.
In the appendices the effects of nonrandomness of mixing are considered and the theory is extended to ternary mixtures.
Energy Calculations for the Linear H3+ Ion System*
Authors: Barker Roland S. , Giddings J. Calvin , Eyring Henry 
Published: April 2005

A study of the dependence of the energy calculations for the linear triatomic hydrogen ion system H3, on a single polarization (electron cloud displacement) parameter g, and on two effective orbital charge parameters Z0 and Zm is presented. The studies, with separate screening parameters for the central and outer atomic orbitals, used normalized approximate integrals. The individual variation of Z0, the charge associated with the outer orbitals, and of Zm, the charge associated with the central orbital, gave little improvement of the energy calculation. From these results with approximate integrals, calculations, at this time, using the exact integrals appear unprofitable.
Only exact integrals are used in the study dealing with the off-center electron cloud parameter, g. These exact integral calculations led to an energy of — 158.07 kcal/mole which is 2.74 kcal/mole better than the best previously obtained value for this linear system.
Cl35 Pure Quadrupole Resonances in Acid Chlorides and Chlorates
Authors: Bray P. J. 
Published: April 2005

The pure quadrupole resonances of Cl35 in acid chlorides of some aliphatic dicarboxylic acids have been observed. No resonances have been found in acid chlorides of aliphatic monocarboxylic acids which retain the unsubstituted CH3 configuration at the chain end not occupied by the COCl group. This absence of resonances is attributed to possible randomness in the crystal structure or thermally activated low-frequency reorientations of groups within the molecule.
Resonances have also been measured in several chlorates, sulfuryl chloride, iodine monochloride, iodine trichloride, and selenium tetrachloride. Structural and bonding discussions are given for the latter two compounds.
Method of Calculating Cross Sections for Molecular Collisions
Authors: Bauer Ernest 
Published: April 2005

The calculation of cross sections for slow inelastic collisions of molecules, such as occur in chemical reactions, shows an interesting combination of classical and quantum-mechanical features. The de Broglie wavelength is small compared with the range of the intermolecular potential so that there exists a relatively well-defined quasi-classical orbit; but in some cases the coupling constant is small compared with unity, and this gives the problem certain quantum-mechanical characteristics. On account of the condition relating to the de Broglie wavelength, a calculation of the total collision cross section requires the knowledge of the partial waves for a large number of values of the angular momentum lh/.
A method is devised to suit these different features. The WKB method lends itself well to this application, with a quasi-classical amplitude and a quantum-mechanical phase for the wave function. We also use the concept of an impact parameter b rather than the orbital quantum number l: this is well suited to describing a quasi-classical orbit, and hence for calculating the total cross section in a case like the present one. As an example of the method, the cross section for excitation of the first vibrational state of a hydrogen molecule resulting from collision with another hydrogen molecule is calculated.
Collision Excitation of Molecular Vibrations in Halogen-Substituted Methanes
Authors: Rossing Thomas D. , Legvold Sam 
Published: April 2005

Departures from the equilibrium between vibrational and translational energies in gases are characterized by relaxation times which depend upon the ease with which vibrations may be excited or de-excited by collisions. The de-excitation process has been discussed by various authors on the basis of the relative velocity of approach of two colliding molecules and on the basis of the relative energy of approach.
The dispersion of ultrasound has been measured in fourteen halogen-substituted methanes and compared with existing data. Binary collisions were found to be responsible for the excitation of vibrations, and all the gases were found to have a single relaxation time indicating a strong intermodal coupling. The probability, in a collision, of exciting or de-exciting molecular vibrations was found to depend upon the relative energy of approach of the molecules. Molecules with the same number of halogen substitutions resemble each other in this respect. The data suggest that the colliding molecules might form a complex molecule with a short lifetime during which energy exchange takes place readily.