Radiolysis Free Ion Yields and Electron Ranges in Polar and Nonpolar Liquids: Fluoromethanes

1973 ◽  
Vol 51 (7) ◽  
pp. 1010-1015 ◽  
Author(s):  
Maurice G. Robinson ◽  
Gordon R. Freeman
Keyword(s):  
Electric Field ◽  
Model Equation ◽  
Secondary Electrons ◽  
Applied Electric Field Strength ◽  
Electric Field Dependence ◽  
Free Ion ◽  
Nonpolar Liquids ◽  
Molecular Complexity ◽  
Ion Yields ◽  
Nonpolar Molecules

The free ion yields at zero applied electric field strength in the liquid fluoromethanes are Gfi0 in CH3F, 1.9 in CH2F2 and 1.1 in CHF3, all at 183 °K, and 0.07 in CF4 at 143 °K. Median ranges ymcd of the secondary electrons were estimated by fitting the electric field dependence of Gfi to a model equation: ymcd = 41 Å in CH3F, 39 Å in CH2F2 and CHF3, and 132 Å in CF4, at the above-mentioned temperatures. The average number of collisions, n, required to thermalize a secondary electron is about 64 000 in liquid Ar, 7 700 in CH4, 660 in C(CH3)4, 360 in CF4, 110 in C3H8, 44 in CH3F, 39 in CH2F2, 35 in CHF3, 17 in H2O, and 12 in CH3OH. The value of n with nonpolar molecules (up to neopentane in size) tends to decrease with increasing molecular complexity and with decreasing sphericity. Presence of a large dipole moment in the molecule decreases n further, and hydrogen bonds reduce n still more. Energy transfer between the electrons and rotational modes of the molecules appears to be important.

X-Radiolysis Ion Yields and Electron Ranges in Liquid Xenon, Krypton, and Argon: Effect of Electric Field Strength

1973 ◽  
Vol 51 (5) ◽  
pp. 641-649 ◽  
Author(s):  
Maurice G. Robinson ◽  
Gordon R. Freeman
Keyword(s):  
Field Strength ◽  
Gas Phase ◽  
Electric Fields ◽  
Zero Field ◽  
Energy Effect ◽  
Secondary Electrons ◽  
Total Ionization ◽  
Field Dependent ◽  
Free Ion ◽  
Ion Yields

X-Radiolysis ion yields were measured at electric fields between 1 and 60 kV/cm in argon at 87 °K, krypton at 148 °K, and xenon at 183 °K. The results were analyzed according to a theoretical model to obtain the total ion yields Gtot,the free ion yields at zero field strength Gfi0 and the most probable penetration ranges b of the secondary electrons in the liquids. The respective values were: Ar, 7.3, 2.9, 1330 Å; Kr, 13.0, 5.8, 880 Å; Xe, 13.7, 7.0, 720 Å. The total ionization yields in these substances are greater in the liquid than in the gas phase, probably due to smaller ionization potentials in the condensed phase (polarization energy effect). Field dependent electron mobilities are also reported.

Electron energy loss in fluids: Thermalization distances in liquid and gaseous sulfur hexafluoride

1990 ◽  
Vol 68 (9) ◽  
pp. 925-929 ◽  
Author(s):  
G. Ramanan ◽  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Sulfur Hexafluoride ◽  
Electron Pair ◽  
Electron Attachment ◽  
Distance Distribution Function ◽  
Electric Field Dependence ◽  
Free Ion ◽  
Gaseous Sulfur ◽  
Ion Yields ◽  
Electron Energy Loss ◽  
Radiation Passing

Ionizing radiation passing through a fluid produces an ion–electron pair by knocking an electron off a molecule. The electron possesses excess energy, which it loses in collisions with molecules as it moves away from the ion. These are stochastic processes. The distance travelled during thermalization determines the probability that the electron ultimately escapes the Coulombic field of the ion to form freely diffusing ions. Free-ion yields were measured in X-irradiated sulfur hexafluoride at 5.7 ≤ d(kg m−3) ≤ 1860, corresponding to the vapor and liquid at 202.8 ≤ T(K) ≤ 324.1. (The critical fluid has dc = 730 kg m−3 and Tc = 318.7 K). The electric field dependence of the yield was best fitted using an electron thermalization distance distribution function F(y) that was Gaussian with a power tail. The most probable thermalization distance bGP was estimated at each density. The density-normalized electron-thermalizing ability of the fluid decreased with increasing gas density and was independent of density in the liquid phase. The dependence is different from those observed in hydrocarbons and might reflect a density effect on the energy dependence of the electron-attachment reaction.

Ionization of Liquid Tetramethyl Germanium by 60Co-γ-Radiation

1990 ◽  
Vol 45 (6) ◽  
pp. 832-834 ◽  
Author(s):  
I. Lopes ◽  
W. F. Schmidt
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Applied Electric Field ◽  
Ionization Chamber ◽  
Parallel Plate ◽  
Ion Pairs ◽  
Guard Ring ◽  
Applied Electric Field Strength ◽  
Γ Radiation ◽  
Free Ion

AbstractThe ionization current produced in liquid tetramethyl germanium by 60Co-γ-radiation was measured with a guard ring type, parallel plate ionization chamber. The yield of ion pairs as a function of the applied electric field strength was determined and the free ion yield without applied electric field was obtained to be Gfi (0) = 0.68 ±0.10.

Electron Mobilities and Ranges in Liquid C1–C3 Hydrocarbons and in Xenon: Effects of Temperature and Field Strength

1974 ◽  
Vol 52 (3) ◽  
pp. 440-446 ◽  
Author(s):  
Maurice G. Robinson ◽  
Gordon R. Freeman
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Temperature Coefficient ◽  
Applied Electric Field ◽  
Effect Of Temperature ◽  
Secondary Electrons ◽  
Applied Electric Field Strength ◽  
Effects Of Temperature ◽  
Arrhenius Temperature

Electron mobilities were measured in ethane, ethylene, propane, cyclopropane, and propylene to complete the studies of the lower hydrocarbons. The effect of temperature on the mobilities in these liquids and in methane, n-butane, and xenon were also measured. Examples of the data are given in the order mobility (cm2/Vs), temperature (K), Arrhenius temperature coefficient (kcal/mol): methane, 430, 140, −0.16; ethane, 0.97, 200, ∼3; ethylene, 0.0030, 170, —; propane, 0.55, 238, ∼3; n-butane, 0.073, 250, ∼4; cyclopropane, 0.0043, 234, ∼4; propylene, 0.008, 234, ∼4; xenon, ∼1200 at 40 V/cm, 198, 0. The mobilities in the C2–C4 hydrocarbons are independent of applied electric field strength E up to 20 kV/cm; that in methane is independent of E up to 2 kV/cm; that in xenon decreases as E−1/2 between 33 and 300 V/cm and decreases slightly more rapidly at higher field strengths. The density-normalized ranges of the secondary electrons in each of the liquids is independent of temperature. The correlation between the ranges of the secondary electrons and the mobilities of thermal electrons observed in other liquids (ref. 2) persists for the simple hydrocarbons.

Electron thermalization-distance distributions in electron-attaching fluids

1990 ◽  
Vol 68 (9) ◽  
pp. 930-934 ◽  
Author(s):  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Carbon Monoxide ◽  
Field Strength ◽  
Electric Field ◽  
Carbon Disulfide ◽  
Sharp Decrease ◽  
Liquid Carbon ◽  
Distance Distributions ◽  
Free Ion ◽  
Ion Yields ◽  
Liquid Carbon Disulfide

The electron ejected from a molecule by an energetic impact moves away from the resultant ion and loses energy to the molecules with which it collides. The distance such electrons travel away from their ions during thermalization can be estimated by measuring the free-ion yields as a function of electric-field strength. This was done in gaseous and liquid carbon disulfide and hexafluorobenzene over wide ranges of densities. The electron thermalization-distance distribution in C6F6 was the same as that in most other liquids; it was a Gaussian distribution with a power tail. However in liquid CS2 the distribution was different, an exponential with a power tail, as in liquid nitrogen and liquid carbon monoxide. The different distributions reflect differences in the thermalization processes. The thermalizing ability of both CS2 and C6F6 is less in the liquid than in the gas. There is an especially sharp decrease in the thermalizing ability of CS2 at the highest densities.

Free ion yields for nonpolar liquids exposed to 1.6–3.5 keV X-rays

1998 ◽  
Vol 51 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Richard A. Holroyd ◽  
T.K. Sham
Keyword(s):  
X Rays ◽  
Free Ion ◽  
Nonpolar Liquids ◽  
Ion Yields

Transient Electric Field Analysis in Consideration of the Electric Field Dependence of Resistivity in the Converter Transformer

2015 ◽  
Vol 135 (12) ◽  
pp. 731-736
Author(s):  
Takuma Terakura ◽  
Kei Takano ◽  
Takanori Yasuoka ◽  
Shigekazu Mori ◽  
Osamu Hosokawa ◽  
...  
Keyword(s):  
Electric Field ◽  
Field Dependence ◽  
Field Analysis ◽  
Electric Field Dependence ◽  
Electric Field Analysis ◽  
Transient Electric Field

Effects of Space Charge on ESEM Gas Amplification

1997 ◽  
Vol 3 (S2) ◽  
pp. 609-610 ◽  
Author(s):  
B.L. Thiel ◽  
M.R. Hussein-Ismail ◽  
A.M. Donald
Keyword(s):  
Electric Field ◽  
Electrostatic Field ◽  
Secondary Electron ◽  
Sample Surface ◽  
Cascade Process ◽  
Secondary Electrons ◽  
Positive Ions ◽  
Space Charges ◽  
Cascade Amplification ◽  
Environmental Sem

We have performed a theoretical investigation of the effects of space charges in the Environmental SEM (ESEM). The ElectroScan ESEM uses an electrostatic field to cause gas cascade amplification of secondary electron signals. Previous theoretical descriptions of the gas cascade process in the ESEM have assumed that distortion of the electric field due to space charges can be neglected. This assumption has now been tested and shown to be valid.In the ElectroScan ESEM, a positively biased detector is located above the sample, creating an electric field on the order of 105 V/m between the detector and sample surface. Secondary electrons leaving the sample are cascaded though the gas, amplifying the signal and creating positive ions. Because the electrons move very quickly through the gas, they do not accumulate in the specimen-to-detector gap. However, the velocity of the positive ions is limited by diffusion.

scholarly journals Electric Field Dependence of the Fluorescence Intensity of Solute Molecules and Fourth Order Effects

1985 ◽  
Vol 40 (9) ◽  
pp. 874-876
Author(s):  
Hilmar Bischof ◽  
Wolfram Baumann
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Field Dependence ◽  
Fourth Order ◽  
Fluorescence Intensity ◽  
Room Temperature ◽  
Order Effects ◽  
Electric Field Dependence ◽  
Total Fluorescence

Abstract The effect of an external electric field on the total fluorescence of solute molecules is studied up to fourth order theoretically, and is checked experimentally with 4´-N,N-dimethylamino- 4-nitrostilbene in dioxane at room temperature.

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