Cation mobility in gaseous, critical, and liquid deuterated methanes

1988 ◽  
Vol 66 (8) ◽  
pp. 1872-1876 ◽  
Author(s):  
M. Antonio Floriano ◽  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Ion Mobility ◽  
Critical Region ◽  
Coexistence Curve ◽  
Number Density ◽  
Experimental Conditions ◽  
Gas Density ◽  
Cation Mobility ◽  
Temperature Coefficients ◽  
Arrhenius Temperature ◽  
Field Strengths

Cation mobilities µ have been measured in the deuterated methanes CHxD4−x (x = 0–4) at field strengths E/n < 4 × 10−21 V m2/molecule, 92 ≤ T/K ≤ 598 and 0.025 ≤ n/1026 molecules m−3 ≤ 171. The mobility in the equilibrium fluids was the same at a given number density n for all five methanes. In the liquid the mobility decreased as the critical region was approached. Changes in nµ in the nonsaturated gases reflected changes in clustering, which was favored at lower T or higher n. The Arrhenius temperature coefficients of ion mobilities at constant gas density near the vapor/liquid coexistence curve nearly equalled those of electron mobilities at similar experimental conditions. The ion mobility in the saturated gas was determined mainly by density and in the liquid by the viscosity.

Cation mobilities in liquid and supercritical C1–C4 hydrocarbons

1980 ◽  
Vol 58 (14) ◽  
pp. 1490-1494 ◽  
Author(s):  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Free Path ◽  
Ion Mobility ◽  
Diffusion Coefficients ◽  
Critical Region ◽  
Mean Free Path ◽  
Liquid Viscosity ◽  
Boiling Points ◽  
Rough Approximation ◽  
The Relationship ◽  
Lower Liquid

The relationship between ion mobility and liquid viscosity is commonly expressed as μ [Formula: see text] η−m. In hydrocarbons the value of m tends to be near 1.0 at η > 5 mP, m > 1.0 at ~5 < η < 1 mP, and m < 1.0 at η < 0.5 mP. Thus there is a maximum in a plot of μη against η−1 and Walden's rule (m = 1.0) is only a rough approximation. The decrease of μη as the critical region is approached is accompanied by an increase in the ratio of diffusion coefficients Dmolec/Dion. Ion mobilities in the liquids well below their normal boiling points are chiefly controlled by the fluidity. At higher temperatures and concomitant lower liquid densities and viscosities μη first increases, due to an increasing ion mean free path, then decreases as the critical region is approached, due to the increasing liquid compressibility and consequent electrostriction about the ion.

Experimental Observation of Convection during Equiaxed Solidification of Transparent Alloys

2006 ◽  
Vol 508 ◽  
pp. 157-162 ◽  
Author(s):  
Sven Eck ◽  
J.P. Mogeritsch ◽  
Andreas Ludwig
Keyword(s):  
Particle Image Velocimetry ◽  
Size Distribution ◽  
Particle Tracking ◽  
Sedimentation Rate ◽  
Particle Image ◽  
Number Density ◽  
Experimental Conditions ◽  
Equiaxed Solidification ◽  
Image Velocimetry ◽  
Experimental Runs

3D samples of NH4Cl-H2O solutions were solidified under defined experimental conditions. The occurring melt convection was investigated by Particle Image Velocimetry (PIV). The occurrence of NH4Cl crystals was observed optically and first attempts were made to quantitatively measure its number density, size distribution and sedimentation rate by PIV and Particle Tracking (PT). In order to prove the reproducibility of the results several experimental runs with equal and slightly modified conditions were analyzed.

Concerning the spectra and solvation process of electrons in liquid butanols

1978 ◽  
Vol 56 (17) ◽  
pp. 2305-2312 ◽  
Author(s):  
Kiyoshi Okazaki ◽  
Gordon R. Freeman
Keyword(s):  
Absorption Band ◽  
Low Temperatures ◽  
Reaction Times ◽  
Optical Absorption Spectra ◽  
Isobutyl Alcohol ◽  
Temperature Coefficients ◽  
Spectral Changes ◽  
Electron Migration ◽  
Arrhenius Temperature ◽  
Short Times

The optical absorption spectra of electrons injected into the isomeric butanols settle into that of the equilibrium solvated state at rates that decrease in the order 1-butanol > isobutyl alcohol > 2-butanol at a given temperature. The relative rates reflect the dipolar reorientation times in the liquids. The Arrhenius temperature coefficients of the rates of spectral changes are ∼30 kJ/mol. The distribution of dipolar reorientation times overlaps that of geminate reaction times of the charges in an irradiated alcohol, so a significant fraction of the electrons undergoes geminate reaction before they are able to become fully solvated. At T < 200 K the fraction increases with decreasing temperature. The concurrence of the solvation process and geminate reaction implies that the former involves, at least in part, electron migration from shallower to deeper traps.There is an indication of structure in the absorption band at low temperatures and short times. The infrared peak converts to one with a maximum at ∼780 nm. The latter slides gradually into the shape of the spectrum of the equilibrium solvated state.For the spectra of the equilibrium solvated state, the energies at the absorption maxima are given by Eεmax (eV) = 3.10 − 0.0038T in isobutyl alcohol and 2.93 − 0.00447 in 2-butanol, between 170 and 300 K. The respective band widths at half heights are 1.53 ± 0.04 and 1.59 ± 0.04 eV, independent of temperature within an uncertainty of 1 meV/K.

Vapour-liquid coexistence curve of some alternative refrigerants in the critical region

1997 ◽  
Vol 29 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Junzo Yata ◽  
Masatomo Hori ◽  
Ken Kohno ◽  
Tatsuo Minamiyama
Keyword(s):  
Critical Region ◽  
Coexistence Curve ◽  
Alternative Refrigerants

ON THE LIQUID–VAPOR COEXISTENCE CURVE OF XENON IN THE REGION OF THE CRITICAL TEMPERATURE

1952 ◽  
Vol 30 (5) ◽  
pp. 422-437 ◽  
Author(s):  
M. A. Weinberger ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Critical Region ◽  
Van Der Waals ◽  
Coexistence Curve ◽  
Packing Materials ◽  
Critical Data ◽  
Van Der Waals Theory ◽  
Liquid Vapor

The liquid–vapor coexistence curves of very pure xenon have been determined in bombs of vertical lengths 1.2 cm. and 19 cm. The longer bomb yielded a flat-topped coexistence curve, the shorter a more rounded curve. The classical van der Waals theory is capable of explaining a large portion of the flat top if effects of gravity are taken into account. Details of the theoretical variation of the width of the flat top with vertical bomb lengths are given. The critical data obtained for xenon are ρc = 1.105 gm./cc., Tc = 16.590 ±.001 °C. The danger of contamination of gases in the critical region on contact with gasket or packing materials is stressed.

The Master Equation for the Dissociation of a Dilute Diatomic Gas. X. How Rotation Causes Low Arrhenius Temperature Coefficients

1973 ◽  
Vol 51 (18) ◽  
pp. 3152-3155 ◽  
Author(s):  
Huw O. Pritchard
Keyword(s):  
Low Temperature ◽  
Temperature Coefficient ◽  
Rate Constants ◽  
Recombination Rate ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Equilibrium Form ◽  
Temperature Coefficients ◽  
Recombination Rate Constant ◽  
Arrhenius Temperature

It is shown that previously calculated nonequilibrium rate constants for the dissociation of H2 and D2 appear to approach a rotationally averaged equilibrium expression at low temperature. This equilibrium form of the rate expression itself has an Arrhenius temperature coefficient for dissociation which is significantly less than the dissociation energy, and the corresponding recombination rate constant has a negative temperature coefficient. The reasons for this are explained.

scholarly journals On the Separation of Enantiomers by Drift Tube Ion Mobility Spectrometry

2021 ◽  
Author(s):  
Roberto Fernandez-Maestre ◽  
Markus Doerr
Keyword(s):  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Gas Flow ◽  
Drift Time ◽  
Chiral Selector ◽  
Buffer Gas ◽  
Chiral Drugs ◽  
Experimental Conditions ◽  
Chiral Selectors ◽  
Racemic Mixtures

<p><a>Racemic mixtures of twelve common </a>a-amino acids and three chiral drugs were tested for the separation of their enantiomers by ion mobility spectrometry (IMS)-quadrupole mass spectrometry (MS). Separations were tested by introducing chiral selectors in the mobility spectrometer buffer gas. (R)-α-(trifluoromethyl) benzyl alcohol, (R)-tetrahydrofuran-2-carbonitrile, (L)-ethyl lactate, methyl (S)-2-chloropropionate, and the R and S enantiomers of 2-butanol and 1-phenyl ethanol were evaluated as chiral selectors. Experimental conditions were varied during the tests including buffer gas temperature, concentration, and type of chiral selectors, analyte concentration, electrospray voltage, electrospray (ESI) solvent pH, and buffer gas flow. The individual enantiomers yielded different drift times for periods of up to 8 hours in a few experiments; such drift times were sufficiently different (~ 0.3 ms) to partially resolve the enantiomers in racemic mixtures, but these mixtures always yielded a single mobility peak at the experimental conditions tested with a drift time similar to that of one of the enantiomers. Energy calculations of the chiral selector –ion interactions showed that these separations are unlikely using 2-butanol as chiral selector but they might be feasible depending on the nature of chiral selectors and the type of enantiomers.</p>

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