Norman Gee

Densities against temperature of 17 organic liquids and of solid 2,2-dimethylpropane

Abstract Densities against temperature of liquids under their equilibrium vapor pressures are reported for three fluoromethanes, three aromatic hydrocarbons, four olefins, bicyclo[2,2,2]octane. 2-methyltetrahydrofuran, and {0.786(1,4- c -C 6 H 8 ) + 0.214C 6 H 6 }. The volume change on melting 2,2-dimethylpropane at the triple-point temperature is 9.6 per cent. A density parameter for n -pentane by Das and coworkers ( J. Chem. Eng. Data 1977 , 22, 3) has been corrected.

Ion and electron mobilities in cryogenic liquids: Argon, nitrogen, methane, and ethane

Ion mobilities at low fields have been measured over the entire liquid range in argon, nitrogen, and methane. Gas‐phase values for argon and nitrogen are also given. Comparison of the ratio of electron to ion mobilities confirmed that the electron remains nearly free in argon and methane liquids but is an anion in liquid nitrogen. At T≲116 K, the product of viscosity and either cation or anion mobility is constant in liquid nitrogen under its vapor pressure. At T>118 K, an abrupt destabilization of the anion in the low density liquid occurs; the breakdown strength of nitrogen should sharply decrease. The utility of breakdown studies in liquid ethane and propane in bridging studies of cryogenic inorganic liquids to studies of normal liquid hydrocarbons is discussed.

Effects of molecular properties on electron transport in hydrocarbon fluids

The electron momentum transfer cross sections σm of each of the hydrocarbon gases possess a minimum at the energy e(eV) noted: propene (0.16), cyclopropane (0.10), propane (0.13), n‐butane (0.14), and i‐butane (0.19). The minimum is much shallower for cyclopropane than for the other molecules. When σm∝e−p with p≳0.5 over the energy distribution of the electrons in the sample, the electron mobility μ increases with increasing gas temperature T, and with increasing applied electric field strength above the threshold (E/n)th. However, upon increasing the gas density n to where an electron can interact with more than one molecule at a time, and at temperatures near the coexistence curve, the temperature dependence of μ increases and the field dependence decreases; these are symptoms of quasilocalization of electrons by density fluctuations in the fluid. The Arrhenius temperature coefficient of mobility Eμ in the constant density vapors, over the range 0.1

Electron transport in low density alkane gases: Effects of chain length and flexibility

The Ramsauer–Townsend (RT) minimum in the electron momentum transfer cross section (σm) occurs at the same energy (ξRT=0.12±0.01 eV) in all n‐alkanes from C2H6 to n‐C10H22. The lack of dependence on chain length indicates that the electron being scattered interacts with a chain segment that contains only two or three carbon atoms. The value of ξRT increases with increasing sphericity of the molecules, being 0.17 eV for i‐butane, 0.22 eV neo‐pentane, and 0.25 eV for methane. At high fields the electron drift velocity attains a ‘‘saturation’’ value (vsat) in the C1 to C5 hydrocarbons: 100 km/s in CH4, 54 km/s in C2H6, 51 km/s in C3H8, 49 km/s in n‐C4H10, and 43 km/s in n‐C5H12. Increasing the molecular sphericity increases vsat: 55 km/s in i‐C4H10 and 57 km/s in neo‐C5H12, to be compared with the values 49 and 43 in the n‐isomers, and 100 km/s in CH4. The value of σm averaged over the thermal velocity distribution, σav, is an order of magnitude smaller than that expected from the simple polarization interac...

Comparison of transition from low to high density transport behavior for ions and neutral molecules in simple fluids

For cation mobility μ in several simple fluids, the transition from normal gas to liquid type behavior occurs in the density region 0.5≲n/nc≲1.9, which corresponds to the viscosity region 0.6≲η/ηc≲2.5. The subscript c refers to the critical fluids and the other fluids are the coexistence vapor and liquid. The fluids range from monatomic to polyatomic molecules: Ar, Xe, N2, CH4. The semihydrodynamic equation provides a reasonable interpretation of the variation of ημ, or the equivalent ηDe/kT for neutral molecules, with η only in the normal gas regime, where n/nc<0.4 and η/ηc<0.5. Under these circumstances, nμ or nDe/kT is nearly constant. In calculating the polarization interaction contribution to the ion scattering cross section, the largest axis of polarizability of the molecule should be used. As n (or η) increases in the region 0.6<n/nc<1.6 (or 0.7<η/ηc<1.9) the value of nμ (or ημ) increases by ∼60%, whereas nDe/kT (or ηDe/kT) for neutral molecules decreases by ∼20%. The ratio (De/kTμ)n has values 5–6...

Electron and ion mobility in carbon disulfide liquid from 163 to 501 K

Electron mobility μe and cation mobility μ+ were measured in liquid carbon disulfide at 163 ≤ T/K ≤ 501. The cations diffuse about half as fast as neutral molecules. Values of μ+ were correlated using a free volume model. The electron mobility increased with increasing T up to ∼460 K and then tended to level off. Unlike in ethers or hydrocarbons, μe /μ+ =6–10 over a very large temperature range, ΔT=338 K. Electron migration by hopping from one group of molecules to the next, as in hexafluorobenzene, is suggested. Empirical correlations of the yields and lifetimes of ortho‐positronium (o‐Ps) with the values of μe in liquids were tested. Values of the static dielectric constant of CS2 were measured at 163–501 K: e=3.4166−1.9826×10−3 T−6.5630×10−6 T 2 +2.2367×10−8 T 3 −2.4997 ×10−11 T 4 .

Electron mobility, free ion yields, and electron thermalization distances in n‐alkane liquids: Effect of chain length

The electron mobility μo was measured as a function of temperature in liquid n‐hexane, n‐heptane, n‐octane, n‐nonane, and n‐undecane, and at 295 K in n‐pentane. Combination of these with earlier measurements of ours showed that μ0 at 295 K decreased monotonically with increasing carbon chain length in n‐alkane liquids from ethane to n‐tetradecane. There was no significant difference between odd and even carbon number compounds. The results were in accord with two‐state interpretations of electron transport. Free ion yields were measured in liquid n‐Cx H2x+2 (4≤x≤14, except 13) and electron thermalization ranges bGP were estimated using the extended Onsager model. The zero field free ion yield G0fi at 295 K decreased with increasing chain length. The density‐normalized thermalization range of electrons was bGPd=(41±1)×10−7 kg/m2 in all n‐alkanes from C4 to C14 under the conditions of this study.

Electron mobilities, free ion yields, and electron thermalization distances in liquid long‐chain hydrocarbons

At 296 K the electron mobility decreased in the liquids n‐hexane>n‐decane>n‐dodecane >n‐tetradecane in accord with the two state model of electron transport (e−il⇄e−qf); the percolation model was inadequate. The temperature dependences were determined for n‐decane, n‐dodecane, n‐tetradecane to T>450 K. Free ion yields were also measured. At a given temperature Gofi was the same in all these liquids to within ±4%. The density‐normalized thermalization ranges of secondary electrons, estimated from the extended Onsager model, were bGPd =(49±1)10−6 kg/m2 under all conditions.

Dielectric constant against temperature for 43 liquids

Abstract Static dielectric constants against temperature are reported for 40 pure compounds and three mixtures. The liquids include carbonyl sulfide, isobutane, neopentane, five alkenes, eight dienes, one triene, three alkynes, two cycloalkanes, six cycloalkenes, six ethers, six aromatic compouds, and { x 1,4- c -C 6 H 8 + (1 − x )C 6 H 6 }.

Electron transport in gaseous ethene and cyclopropane: Temperature and electric field effects

To check whether ethene and cyclopropane display a Ramsauer–Townsend minimum in their electron momentum transfer cross sections, electron drift velocities were measured over much larger temperature ranges than previously. Ethene: 130≤T(K)≤647, 0.25≲n(1025 molecule/m3)≲3.0. Cyclopropane: 185≤T(K)≤644, 0.13≲n(1025 molecule/m3)≲18. At 294 K vd at a given E/n was independent of n up to the highest n used. In both gases vd increases linearly with E/n up to ∼0.3 Td, then tends towards saturation at ∼4 Td. In ethene vsat is ∼17 km/s, and is ∼35 km/s in cyclopropane. The value of vsat in alkanes correlates with the inverse polarizability. Ethene has a Ramsauer–Townsend minimum in its momentum transfer cross section at 0.08 eV, and cyclopropane has one at 0.07 eV.