Polarizability α (ω, <i>T</i>, ρ) of Small Molecules in the Gas Phase

Kerl, K.; Hohm, Uwe; Varchmin, H.

doi:10.1002/bbpc.19920960517

Cited by 24 publications

(11 citation statements)

References 33 publications

(19 reference statements)

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“…The values for the relevant properties of EMI-BF 4 , air, and CO 2 used in our analysis at each of these temperatures are listed in Table 1, together with references to the literature from which they originate. In addition, the values α Air = 1.70 Å 3 (ref. 28) and α CO 2 = 2.60 Å 3 (ref.…”

Section: Resultsmentioning

confidence: 99%

Electrical mobilities of multiply charged ionic-liquid nanodrops in air and carbon dioxide over a wide temperature range: influence of ion-induced dipole interactions

Fernández‐García

Mora

2014

Phys. Chem. Chem. Phys.

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The electrical mobilities of hundreds of mass-selected, multiply charged nanodrops (2-6 nm in diameter) of the ionic liquid EMI-BF4 have been measured in air and CO2 at temperatures, T, ranging from 20 to 100 °C, extending previous studies, based on EMI-N(CN)2 nanodrops in air at 20 °C, to other temperatures and drift gases. The known compressibility of EMI-BF4 removes prior slight ambiguities in the mass-based determination of nanodrop diameters. We confirm the previous finding that the collision cross-sections Ω of these nanodrops, inferred from their electrical mobilities, are related to their diameters d via a relation of the form Ω ≈ ξπ/4(d + d(g))(2) (1 + βε*) (1 + f(Kn))(-1), where ε* is the ratio between the polarization and thermal energies of the ion-gas molecule system at contact, f(Kn) is a continuum-correction that vanishes in the free-molecule limit, and the coefficients dg, β, and ξ are inferred experimentally as functions of temperature and drift gas. This expression for Ω(d,z) enables determining true (geometric) cross-sections of globular ions from their measured electrical mobilities in molecular gases. We also corroborate prior reports that the drag-enhancement factor ξ, which remains nearly constant with temperature and drift-gas, exceeds slightly the value ξm≈ 1.36 established by Millikan's oil drop measurements. Unexpectedly, the coefficient β shows a significant temperature dependence, suggesting that the ion-gas molecule scattering process is affected by T. The effective gas-molecule collision diameter dg is seen to decrease with T, and takes a value in excess of 0.45 nm in CO2 at 20 °C, considerably larger than in room-temperature air.

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Section: Resultsmentioning

confidence: 99%

Electrical mobilities of multiply charged ionic-liquid nanodrops in air and carbon dioxide over a wide temperature range: influence of ion-induced dipole interactions

Fernández‐García

Mora

2014

Phys. Chem. Chem. Phys.

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“…in the field of intermolecular forces [16,17], light scattering phenomena [18,19], physics of clusters [20,21], and other more [22], the description of the frequency dependence of a(w) in terms of so-called Cauchy moments S(-2k) (see (3) below) is also of great value since the S(-2k) are related to all oscillator strengthsf, and transition frequencies Woi of the atomic or molecular species, respectively. It has been also shown, that the S(-k) are useful for estimating static second hyperpolarizabilities 7(0; 0, 0, 0) [23].…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of the dispersion in the mean linear dipole polarizability α(ω) of small hydrocarbons and evaluation of Cauchy moments between 325 nm and 633 nm

Hohm

1993

Molecular Physics

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Print) 1362-3028 (Online) Journal homepage: http://www.tandfonline.com/loi/tmph20 Experimental determination of the dispersion in the mean linear dipole polarizability α(ω) of small hydrocarbons and evaluation of Cauchy moments between 325 nm and 633 nm Uwe Hohm To cite this article: Uwe Hohm (1993) Experimental determination of the dispersion in the mean linear dipole polarizability α(ω) of small hydrocarbons and evaluation of Cauchy moments between 325 nm and 633 nm, Molecular Physics, 78:4, 929-941,The frequency dependent linear mean dipole polarizability a(w) of the hydrocarbons CH4, C2H6, C3Hs, n-C4Hl0, C(CH3)4 (neopentane), C2H4, C3H 6, and cyclo-_C3H 6 has been determined by precise measurements of the refractive index in the frequency range between 0.07198116 a.u. (A = 632.990nm) and 0"1401389a.u. (A = 325-130nrn). This is the first experimental determination of a(w) in the UV frequency region of neopentane and cyclopropane. It will be shown, that the uncertainty in the relative dispersion Aa(w)/Aw of c~(w) is mostly determined by the uncertainty in the frequency of the radiation sources used. In addition, Cauchy moments S(-2), S(-4), S(-6), and S(-8) are calculated with an extended numerical procedure from the measured data sets, showing that a simple Gaussian least-squares fit of a(w) in w 2 is not sufficient to obtain S(-2k). In additon, some data of the relative dispersion of the second refractivity virial coefficient of some of these gases are presented.

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“…The full formulae have been evaluated in [1,33], but for the sake of clearness they are also given in Appendix Al. In detail, there is the well-known Kirkwood fluctuation contribution /I=/IW (7) and the influence of high intermolecular field-strengths due to a dispersion like interaction via the second hyperpolarizability y:…”

Section: Ar(co T) =mentioning

confidence: 99%

“…where b and c are only known for some gases and are taken from [7]. The very small 7-dependence of a 0 of the noble gases [5] is neglected.…”

Section: Modelling Of B R (Co T)mentioning

confidence: 99%

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Frequency-and Temperature-Dependence of Second Refractivity Virial Coefficients

Hohm

1993

Zeitschrift Für Naturforschung A

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A reasonable heuristic extrapolation of a theory given by Buckingham is used to estimate the frequency-and temperature-dependence of the second refractivity virial coefficient. The calculations are carried out for the atoms He, Ne, Ar, Kr, Xe and the small molecules H 2 , N 2 , 0 2 , HCl, C0 2 , N 2 0, NH 3 , CH 4 , C 2 H 4 , and SF 6 . In some cases the frequency-dependence of B R (co, T) is compared with experimental values, showing sometimes considerable deviations between experiment and the heuristic approach used in this work.

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Polarizability α (ω, T, ρ) of Small Molecules in the Gas Phase

Cited by 24 publications

References 33 publications

Electrical mobilities of multiply charged ionic-liquid nanodrops in air and carbon dioxide over a wide temperature range: influence of ion-induced dipole interactions

Electrical mobilities of multiply charged ionic-liquid nanodrops in air and carbon dioxide over a wide temperature range: influence of ion-induced dipole interactions

Experimental determination of the dispersion in the mean linear dipole polarizability α(ω) of small hydrocarbons and evaluation of Cauchy moments between 325 nm and 633 nm

Frequency-and Temperature-Dependence of Second Refractivity Virial Coefficients

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