The Ionization Potential and the Polarizability of Molecules

Reed, T. M.

doi:10.1021/j150527a012

Cited by 34 publications

(26 citation statements)

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“…Further evidence in support of the IET based polarizability analysis (for O 2 and CO) come from the work of Reed [48] and Bogaard et al [49] The molecular polarizability for O is given by 1.75 10 À40 Cm 2 V À1 [we converted the unit from cm 3 (Gaussian) to SI]. [48] The molecular polarizability [49] for CO is 2.031 10 À40 Cm 2 V…”

mentioning

confidence: 72%

Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

et al. 2010

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Despite many important applications of α-Fe(2)O(3) and Fe doped SnO(2) in semiconductors, catalysis, sensors, clinical diagnosis and treatments, one fundamental issue that is crucial to these applications remains theoretically equivocal--the reversible carrier-type transition between n- and p-type conductivities during gas-sensing operations. Herein, we present an unambiguous and rigorous theoretical analysis in order to explain why and how the oxygen vacancies affect the n-type semiconductors α-Fe(2)O(3) and Fe-doped SnO(2), in which they are both electronically and chemically transformed into a p-type semiconductor. Furthermore, this reversible transition also occurs on the oxide surfaces during gas-sensing operation due to physisorbed gas molecules (without any chemical reaction). We make use of the ionization energy theory and its renormalized ionic displacement polarizability functional to reclassify, generalize and explain the concept of carrier-type transition in solids, and during gas-sensing operation. The origin of such a transition is associated with the change in ionic polarizability and the valence states of cations in the presence of oxygen vacancies and physisorped gas molecules.

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confidence: 72%

Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

et al. 2010

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“…When the electron energy exceeds the ionization potential, dissociative ionization will produce various fragments and species. Although tetrafluoromethane possesses a relatively high ionization potential (17.8 eV), it was selected as a process gas due to its fluorine/carbon (F/C) ratio, which corresponds with the ability to produce an overabundance of excited fluorine species in the plasma state (Kiser and Hobrock 1965;Reed 1955). Surfeit fluorine radicals can bind onto the surface of saturated and unsaturated hydrocarbons through hydrogen abstraction and double bond addition pathways, respectively (Fig.…”

Section: Tetrafluoromethane Plasma Treatment Of Polyethersulfone and mentioning

confidence: 99%

Plasma modification of microporous polymer membranes for application in biomimetic dissolution studies

Puppolo

Hughey²,

Weber³

et al. 2017

AAPS Open

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Biorelevant dissolution is an indispensable tool utilized during formulation development and optimization for the prediction of in vivo bioavailability of pharmaceutical agents. Within that framework, membrane-permeation dissolution methodologies are widely used to model drug absorption. The current work evaluates polymer membrane surface modifications for production of biomimetic membranes to be employed in biorelevant dissolution studies. Biomimetic membranes exhibit hydrophilic and hydrophobic properties to simulate the intestinal membrane environment. Low temperature plasma treatment of microporous polyethersulfone (PES), nylon and polypropylene (PP) polymer membranes was applied to produce low energy surface layers with permanent hydrophobic and hydrophilic functionalities. Surface modifications on microporous polymer membranes were achieved by plasma treatments using tetrafluoromethane (CF 4 ), perfluorohexane (C 6 F 14 ), dichloromethane (DCM) and water (H 2 O). Surface characterization of treated membranes was evaluated using scanning electron microscopy energy dispersive x-ray spectroscopy (SEM-EDS), water contact angle (CA) and x-ray photoelectron spectroscopy (XPS) techniques. SEM-EDS analysis of polymer membranes treated with fluorinated and chlorinated solvents/gases depicts altered surface morphologies with enriched porosity. SEM-EDS and XPS analyses demonstrate the chemical modification at the surface of treated membranes is strongly influenced by the type of treatment gas or solvent. Results show fluorination as a more effective and less destructive treatment technique. XPS confirmed the presence of elemental fluorine functional groups at the surface of the PES and nylon membranes. Evaluating elemental changes (F/C ratio) from multiple techniques confirms fluorinated plasma treatments are localized to the surface of the membrane and do not significantly affect the bulk properties. In a supplemental study, a detailed comparison of the plasma treated polymer membranes and porcine intestines revealed the biomimetic nature of the modified membranes.

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“…Notionally, averaged molecular polarisabilities are obtained as the sum of averaged bond polarisabilities of each of the bonds in the molecule [3], so that the total dispersion interaction will be a sum of such terms. For isotropic molecules, the expression reduces to equation (1). A simple combining rule would not be directly obtainable from the Hudson-McCoubrey method, since an extra equation would be required to solve for both components of the polarisability.…”

Section: Large Non-polar Moleculesmentioning

confidence: 99%

“…Over fifty years ago Reed [1] showed that the usual form for the combining rule for intermolecular attractive forces in unlike binary interactions, known as the Berthelot, or geometric-mean rule (given as equation (9) in this paper), is improved by the inclusion of ionisation potentials and molecular size. This results from consideration of the London theory of dispersion interactions [2], which is frequently described (e.g.…”

Section: Introductionmentioning

confidence: 96%