Molecular structure effects on electron ranges and mobilities in liquid hydrocarbons: chain branching and olefin conjugation: mobility model

1976 ◽  
Vol 54 (5) ◽  
pp. 744-759 ◽  
Author(s):  
J.-P. Dodelet ◽  
K. Shinsaka ◽  
G. R. Freeman
Keyword(s):  
Molecular Structure ◽  
Energy Transfer ◽  
Liquid Phase ◽  
Electron Energy ◽  
Cross Sections ◽  
Mobility Model ◽  
Thermal Electron ◽  
Interaction Radius ◽  
In Series ◽  
Electron Migration

The effect of molecular structure on electron behavior in liquids was studied by measuring secondary electron penetration ranges bGP and thermal electron mobilities ue in substituted methanes and ethylenes. The penetration ranges are smaller (energy transfer cross sections are larger) when the alkane molecules are less rigid. It was confirmed that the epithermal electron energy transfer interaction radius in a liquid phase alkane molecule is limited to two C—C bonds in series. This modifies the earlier noted correlation between bGP and the degree of sphericity of the molecules. For example, the density normalized range bGPd in the relatively sphere-like tetraethylmethane (54 × 10−8 g/cm2) is more similar to that in the distinctly nonspherical diethylmethane (n-pentane, 43 × 10−8 g/cm2) than to that in the sphere-like tetramethylmethane (126 × 10−8 g/cm2). Tetraethylmethane is too large for the entire molecule to interact with an electron in the liquid phase, and the possibility of rotations about the C—C bonds in the ethyl groups makes the molecule less rigid. Electrons sense these relatively sphere-like molecules to be similar to those of a n-alkane. Connecting tert-butyl groups to olefinic or acetylenic carbons creates sphere-like quasi neopentyl groups which greatly enhance electron ranges in the unsaturated compounds. In conjugated olefins cis–trans effects are largely overshadowed by the general efficiency of these compounds as electron energy sinks. The earlier noted correlation between bGP and ue contains fine structure. For a given value of bGP, ue increases in the order n-alkane < cyclo or branched alkane < olefin. Electron mobilities are interpreted in terms of a model that contains a Gaussian distribution of solvated electron state energies, a conduction band, and thermally activated transitions between them. The model is a combination of our treatment of electrons in ethers and Schiller's treatment of electrons in hydrocarbons. The percolation model does not provide a sufficiently complete interpretation of electron migration in hydrocarbons.

scholarly journals New electron energy transfer and cooling rates by excitation of O2

1998 ◽  
Vol 16 (8) ◽  
pp. 1007-1013 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Energy Transfer ◽  
Electron Energy ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
Electron Cooling ◽  
Vibrationally Excited ◽  
Cooling Rates ◽  
Production Frequency ◽  
Electron Energy Loss ◽  
Analytical Expressions

Abstract. In this work I present the results of a study of the electron cooling rate, the production rates of vibrationally excited O2, and the production frequency of the O2 vibrational quanta arising from the collisions of electrons with O2 molecules as functions of the electron temperature. The electron energy transfer and cooling rates by vibrational excitation of O2 have been calculated and fitted to analytical expressions by use of the revised vibrationally excited O2 cross sections. These new analytical expressions are available to the researcher for quick reference and accurate computer modeling with a minimum of calculations. It is also shown that the currently accepted rate of electron energy loss associated with rotational transitions in O2 must be decreased by a factor of 13.

scholarly journals New electron energy transfer rates for vibrational excitation of N<sub>2</sub>

1998 ◽  
Vol 16 (2) ◽  
pp. 176-182 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Energy Transfer ◽  
Electron Energy ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
Atmospheric Composition ◽  
Vibrationally Excited ◽  
Transfer Rates ◽  
Composition And Structure ◽  
Production Frequency ◽  
Analytical Expressions

Abstract. In this paper we present the results of a study of the electron cooling rate, the production rates of vibrationally excited N2(v), and the production frequency of the N2 vibrational quanta arising from the collisions of electrons with unexcited N2(0) and vibrationally excited N2(1) molecules as functions of the electron temperature. The electron energy transfer rates for vibrational excitation of N2 have been calculated and fit to analytical expressions by use of the revised vibrationally excited N2 cross sections. These new analytical expressions are available to the researcher for quick reference and accurate computer modeling with a minimum of calculations.Key words. Atmospheric composition and structure · Thermosphere · Ionosphere · Modeling and forecasting

Mobilities and Ranges of Electrons in Liquids: Effect of Molecular Structure in C5–C12 Alkanes

1972 ◽  
Vol 50 (16) ◽  
pp. 2667-2679 ◽  
Author(s):  
Jean-Pol Dodelet ◽  
Gordon R. Freeman
Keyword(s):  
Inelastic Scattering ◽  
Cross Sections ◽  
Electron Mobility ◽  
Electron Interaction ◽  
Thermal Electron ◽  
Secondary Electrons ◽  
In Series ◽  
The Difference ◽  
Branched Chain ◽  
Ion Yields

X-radiolysis free ion yields and electron mobilities were measured in a series of branched chain hydrocarbons at several temperatures. The numbers listed after the following compounds are the temperature (K), Gfi, most probable penetration range of the secondary electrons (Å) and thermal electron mobility (cm2/V s): 2,2-dimethylpropane (neopentane), 294, 1.09, 213, 50; 2,2,3,3-tetramethylbutane, 379, 0.80, 130, –; 2,2,4,4-tetramethylpentane, 295, 0.83, 158, 24; 2,2,5,5-tetramethylhexane, 293, 0.67, 138, 12; 2,2,6,6-tetramethylheptane, 293, 0.47, 113, –; 2,2,7,7-tetramethyloctane, 383, 0.58, 100, –; 2,2,3,3-tetramethylpentane, 295, 0.42, 102, 5.2; cyclohexane, 294, 0.16, 67, 0.45. The difference between the activation energies of the reactions[Formula: see text]and[Formula: see text]is (E15–E14) ≈ (2 to 3)RT for twenty two different hydrocarbons, including olefins and benzene. The rate of energy loss by epithermal electrons in liquid hydrocarbons increases with increasing anisotropy of polarizability of the molecules or groups; the range of the electron interaction in a given molecule appears to be about two C—C bonds in series (groups up to neopentyl in size). There is a correlation between the mobilities of thermal electrons in liquids and the penetration ranges of the secondary electrons in the liquids. The electron mobility in a liquid alkane appears to be limited by inelastic scattering. The inelastic scattering cross sections for both thermal (< 0.1 eV) and epithermal (~ 1 eV) electrons in liquid alkanes are affected in similar ways by the anisotropy of polarizability of the molecules. In both instances the scattering apparently involves rotational (librational) excitation of the medium.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Antibiotic Distribution in a Bone Cement Spacer Model

2007 ◽  
Vol 17 (4) ◽  
pp. 218-223 ◽  
Author(s):  
K. Shiramizu ◽  
V. Lovric ◽  
A.M.D. Leung ◽  
W.R. Walsh
Keyword(s):  
Liquid Phase ◽  
Bone Cement ◽  
Cross Sections ◽  
High Dose ◽  
Cement Spacer ◽  
Traditional Technique ◽  
Low Viscosity ◽  
Significant Difference ◽  
Group A ◽  
Medium Viscosity

Purpose To mix high dose antibiotic powder to the bone cement more easily, Hanssen et al reported mixing the antibiotics with the cement during its liquid phase but made no comments about the relevance of cement viscosity and antibiotic distribution. The purpose of this study was to investigate the effect of the cement mixing technique and cement viscosity on the antibiotics distribution in a cement spacer model. Methods Thirty cylindrical models from three groups were examined. Group A was made by mixing the antibiotics with medium viscosity cement prior to adding the liquid monomer (traditional technique). Group B was made by mixing the antibiotics with medium viscosity cement during its liquid phase (Hanssen's technique). Group C was made by traditional technique with low viscosity cement. In all groups 2 g of tetracycline was used. Three 0.1 mm thick cross sections from each spacer model were examined under the fluorescent microscope. The fluorescent spots of tetracycline were calculated automatically in pixels. To evaluate the distribution of the antibiotics in the spacer model, we selected the cross section with the highest number of pixels and the one with the lowest number of pixels from each of the three cross sections and calculated the difference between them. The distribution disequilibrium was compared between group A and B, A and C. Results No significant difference was observed in either comparison. Conclusion The Hanssen's mixing technique can be used when using high dose antibiotics, and either medium or low viscosity cement could be used in terms of antibiotic distribution.

From photosensitizers to light harvesters adapting the molecular structure in all-BODIPY assemblies

2021 ◽  
Author(s):  
Edurne Avellanal Zaballa ◽  
Alejandro Prieto ◽  
Carolina Diaz Norambuena ◽  
Jorge Bañuelos ◽  
Antonia R Agarrabeitia ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Energy Transfer ◽  
Singlet Oxygen ◽  
Halogen Free

Herein we detail a protocol to design dyads and triads based solely on BODIPY dyes as halogen-free singlet oxygen photosensitizers or energy transfer molecular cassettes. The conducted photonic characterization reveals...

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