The pressure dependence of refractivity of polar gases

1960 ◽  
Vol 255 (1282) ◽  
pp. 427-433 ◽  
Keyword(s):  
Pressure Dependence ◽  
Sulphur Dioxide ◽  
Experimental Error ◽  
Methyl Chloride ◽  
Molecular Polarizability ◽  
Refractive Indices ◽  
Methyl Fluoride ◽  
Carbon Tetrafluoride ◽  
First Order

The refractive indices of several gases have been measured at varying pressures in the range 0 to 50 cm. For carbon tetrafluoride, methyl fluoride and methyl chloride the refractivity varies directly with the density within the limits of experimental error. For ammonia and sulphur dioxide the increase of refractivity with pressure is less than would correspond to the increase in density. This may be interpreted in terms of a negative ‘first-order hyperpolarizability' for the polar vapours, whose molecular polarizability is being decreased by the influence of the field due to neighbouring molecular dipoles.

Temperature dependence of vibrational relaxation times in gases

1958 ◽  
Vol 244 (1237) ◽  
pp. 212-219 ◽  
Keyword(s):  
Energy Transfer ◽  
Methyl Bromide ◽  
Sulphur Dioxide ◽  
Vibrational Relaxation ◽  
Transition Probability ◽  
Relaxation Times ◽  
Methyl Chloride ◽  
Collision Theory ◽  
Ultrasonic Dispersion ◽  
Carbon Tetrafluoride

Ultrasonic dispersion measurements at varying temperatures, extending over the range 290 to 580° K, have been made on gaseous ethylene, cyclo propane, carbon tetrafluoride, methyl chloride and methyl bromide. The results are correlated with previous measurements on methyl fluoride and sulphur dioxide. The non-polar gases show a steady rise in the probability of energy transfer between translation and vibration with rise in temperature. The transition probability, P 10 , is found to vary with exp — T -½ in accordance with current collision theory, but the quantitative dependence cannot be predicted from molecular properties. The polar gases behave in a similar way at higher temperatures, but at lower temperatures the transition probability increases with falling temperature. This is interpreted as due to increasing predominance of oriented collisions, which are specially favourable for energy transfer, between polar molecules at lower temperatures.

scholarly journals Kinetics of thiamin cleavage by sulphite

1969 ◽  
Vol 113 (4) ◽  
pp. 611-615 ◽  
Author(s):  
J. Leichter ◽  
M. A. Joslyn
Keyword(s):  
Aqueous Solutions ◽  
Rate Constant ◽  
Sulphur Dioxide ◽  
First Order ◽  
Ph Values ◽  
Rate Of Reaction ◽  
Kinetics Of

Results are presented on the rate of thiamin cleavage by sulphite in aqueous solutions as affected by temperature (20–70°), pH(2·5–7·0), and variation of the concentration of either thiamin (1–20μm) or sulphite (10–5000μm as sulphur dioxide). Plots of the logarithm of percentage of residual thiamin against time were found to be linear and cleavage thus was first-order with respect to thiamin. At pH5 the rate was also found to be proportional to the sulphite concentration. In the pH region 2·5–7·0 at 25° the rate constant was 50m−1hr.−1 at pH5·5–6·0, and decreased at higher or lower pH values. The rate of reaction increased between 20° and 70°, indicating a heat of activation of 13·6kcal./mole.

OPTICAL PARAMETRIC INTERACTION IN INFRARED REGION CRYSTALS

2013 ◽  
Vol 22 (03) ◽  
pp. 1350033
Author(s):  
RENA J. KASUMOVA
Keyword(s):  
Dispersion Coefficient ◽  
Infrared Region ◽  
Parametric Interaction ◽  
Signal Wave ◽  
Refractive Indices ◽  
Phase Matching ◽  
Angular Dispersion ◽  
First Order ◽  
Optical Parametric ◽  
Pump Signal

In this work, parametric interaction is investigated with the account for phase change of interacting pump, signal and idler waves in the materials of infrared (IR) range of spectrum in case of Zn 1-x Mg x Se crystal. We give an analysis of the threshold intensity of pumping for Zn 0.75 Mg 0.25 Se crystal under conditions of the existing experiment, as well as the analytical expression for obtaining the optimum value of phase mismatch Δopt, at which maximum of signal wave reinforcement is reached. The values of refractive indices, angle of phase matching and angular dispersion coefficient of the first-order for Zn 0.52 Mg 0.48 Se have been calculated.

AN APPARATUS FOR THE MEASUREMENT OF DIELECTRIC CONSTANTS OF ADSORBED GASES AT FREQUENCIES UP TO 100 Mc./Sec.

1955 ◽  
Vol 33 (2) ◽  
pp. 268-278 ◽  
Author(s):  
M. H. Waldman ◽  
R. McIntosh
Keyword(s):  
Sulphur Dioxide ◽  
Experimental Error ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Frequency Range

The design of an apparatus suitable for the measurement of dielectric constants at frequencies up to 106 Mc./sec. is shown. The apparatus was used to measure changes in capacitance with volume adsorbed for the system sulphur dioxide – rutile at about 3.5 °C. and for frequencies of 13, 36, and 106 Mc./sec. The results failed to reveal any dispersion due to the adsorbed matter in this frequency range. The dielectric behavior observed is the same, within experimental error of a few per cent, as that found by Channen and McIntosh for the same system at 3.7 Mc./sec.

Pressure Dependence of the de Haas – van Alphen Effect in Ytterbium

1974 ◽  
Vol 52 (17) ◽  
pp. 1622-1627 ◽  
Author(s):  
A. J. Slavin ◽  
W. R. Datars
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Transformation ◽  
Pressure Dependence ◽  
Experimental Error ◽  
Solid Helium ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Pressure Medium ◽  
The Magnetic Field

The de Haas–van Alphen effect and the h.c.p.–f.c.c. phase transformation of ytterbium were studied with the magnetic field along the [0001] direction in the h.c.p. phase, using pressures up to 4 kbar. Solid helium was used as the pressure medium. The pressure dependence of the three dHvA frequencies in the h.c.p. phase for the [0001] magnetic field direction was linear within experimental error with dF/dP = −1.2 ± 0.2 T/kbar for F(P = 0) of 35.4 T, dF/dP = 0.30 ± 0.03 T/kbar for F(P = 0) of 142.5 T, and dF/dP = −0.78 ± 0.10 T/kbar for F(P = 0) of 156.4 T. The dHvA amplitude in the h.c.p. phase was independent of pressure up to the phase transition and no dHvA effect was observed in the f.c.c. phase. The pressure of the phase transformation at 1.2 K was determined to be 2.15 ± 0.05 kbar.

The refractive indices and Verdet constants of the inert gases

1960 ◽  
Vol 259 (1298) ◽  
pp. 424-431 ◽  
Keyword(s):  
Experimental Data ◽  
Refractive Index ◽  
Atomic Hydrogen ◽  
Experimental Error ◽  
Atomic System ◽  
Inert Gases ◽  
Refractive Indices ◽  
Verdet Constant

A method is suggested by which the refractive index and Verdet constant of an atomic system may be derived theoretically. It is applied to atomic hydrogen and to the inert gases and a comparison is made with experimental data. The Verdet constant of neon is not anomalous. The origin of the suggestion appears to be an underestimate of the experimental error. The analysis yields values of th e polarizabilities of th e inert gases which are respectively He, 1-384; Ne, 2-663; Ar, 11-080; K r, 16-734; X e, 27-292 in units of α 3 0

AbinitioMO calculation of the anharmonic force field of methyl fluoride and methyl chloride

1984 ◽  
Vol 81 (4) ◽  
pp. 1951-1959 ◽  
Author(s):  
Shigeo Kondo ◽  
Yoshinori Koga ◽  
Taisuke Nakanaga
Keyword(s):  
Force Field ◽  
Methyl Chloride ◽  
Methyl Fluoride ◽  
Anharmonic Force

Pyrolysis of Trifluoroacetaldehyde

1973 ◽  
Vol 51 (14) ◽  
pp. 2292-2296 ◽  
Author(s):  
Michael T. H. Liu ◽  
Leon F. Loucks ◽  
Robert C. Michaelson
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Free Radicals ◽  
Rate Equation ◽  
Pressure Dependence ◽  
Inert Gas ◽  
Order Process ◽  
First Order ◽  
Pressure Region ◽  
High Pressure Region

The thermal decomposition of trifluoroacetaldehyde has been studied over the 460–520 °C temperature range, and at pressures from 4 to 400 mm Hg. The experimental rate equation in the high-pressure region is of the form: Rate = k[CF3CHO]3/2 where[Formula: see text]The results are consistent with a mechanism initiated by a first order process and terminated by a second order recombination of two CF3 free radicals. At lower pressures (40 mm Hg), the ratio of kinit/kterm is pressure dependent and the overall order increases. The effects of added inert gas confirm this pressure dependence.

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