Effect of density on the total ionization yields in X-irradiated argon, krypton, and xenon

1977 ◽  
Vol 55 (11) ◽  
pp. 1838-1846 ◽  
Author(s):  
Sam S.-S. Huang ◽  
Gordon R. Freeman
Keyword(s):  
Field Strength ◽  
Gas Phase ◽  
Excited States ◽  
Electric Fields ◽  
Energy Gap ◽  
Low Density ◽  
Infinite Field ◽  
Free Ions ◽  
Total Ionization ◽  
Higher Excited States

The amounts of ionization produced by absorption of X radiation in the liquids xenon, krypton, and argon are respectively 1.5, 1.4, and 1.2 times greater than those produced by the absorption of the same energy in the corresponding low density gases. The yields of free ions in the irradiated liquids were measured at applied electric fields 1–40 kV/cm and extrapolated to infinite field strength. The total number of ionizations per 100 eV absorbed was Gtot = 6.6 in xenon, 6.0 in krypton, and 4.5 in argon. The reason that the ionization yield is larger in the liquid than in the corresponding low density gas is partly that the energy gap Eg between the top of the valence band and the bottom of the conduction band in the liquid is smaller than the gas phase ionization potential IP. The ratio IP/Eg = 1.36 for xenon (Roberts and Wilson), 1.27 for krypton, and 1.17 for argon (from data of Jortner et al.). An extra source of ionization in the liquid might be reaction of the higher excited states, M* + M → [M2+ + e−].

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.

GAS-PHASE ELECTRONIC SPECTRA OF POLYACETYLENE CATIONS: RELEVANCE OF HIGHER EXCITED STATES

2010 ◽  
Vol 140 (1) ◽  
pp. 203-205 ◽  
Author(s):  
C. A. Rice ◽  
V. Rudnev ◽  
R. Dietsche ◽  
J. P. Maier
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Electronic Spectra ◽  
Higher Excited States

Investigation of Adsorption Effect of Carbon Monoxide on Coniine: A DFT Study

2021 ◽  
Vol 17 ◽  
Author(s):  
Siyamak Shahab ◽  
Masoome Sheikhi ◽  
Mehrnoosh Khaleghian ◽  
Marina Murashko ◽  
Mahin Ahmadianarog ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Adsorption Effect ◽  
Chemical Shift Tensors ◽  
Solvent Water ◽  
Donor And Acceptor ◽  
Before And After ◽  
Electron Donor And Acceptor

: For the first time in the present study, the non-bonded interaction of the Coniine (C8H17N) with carbon monoxide (CO) was investigated by density functional theory (DFT/M062X/6-311+G*) in the gas phase and solvent water. The adsorption of the CO over C8H17N was affected on the electronic properties such as EHOMO, ELUMO, the energy gap between LUMO and HOMO, global hardness. Furthermore, chemical shift tensors and natural charge of the C8H17N and complex C8H17N/CO were determined and discussed. According to the natural bond orbital (NBO) results, the molecule C8H17N and CO play as both electron donor and acceptor at the complex C8H17N/CO in the gas phase and solvent water. On the other hand, the charge transfer is occurred between the bonding, antibonding or nonbonding orbitals in two molecules C8H17N and CO. We have also investigated the charge distribution for the complex C8H17N/CO by molecular electrostatic potential (MEP) calculations using the M062X/6-311+G* level of theory. The electronic spectra of the C8H17N and complex C8H17N/CO were calculated by time dependent DFT (TD-DFT) for investigation of the maximum wavelength value of the C8H17N before and after the non-bonded interaction with the CO in the gas phase and solvent water. Therefore, C8H17N can be used as strong absorbers for air purification and reduce environmental pollution.

Zur Berechnung der chemischen Verschiebung unter besonderer Berücksichtigung des paramagnetischen Terms / Attempts to the Calculation of the Chemical Shift with Especial Consideration of the Paramagnetic Term

1977 ◽  
Vol 32 (12) ◽  
pp. 1541-1543
Author(s):  
H. Sterk ◽  
J. J. Suschnigg
Keyword(s):  
Chemical Shift ◽  
Excited States ◽  
Ground State ◽  
Energy Gap

Abstract Attempts to the Calculation of the Chemical Shift with Especial Consideration of the Paramagnetic Term The calculation of the paramagnetic term according to the Pople formalism of the chemical shift is expanded. The hitherto constant value of the energy gap between the ground state and the excited states is replaced by the value of the lowest lying excitation. This leads to a remarkably better differentiation of the paramagnetic terms of different compounds. The influence is shown on ethane, ethene and ethine.

Radiolysis of methylcyclopentane. III. Liquid phase mechanism and comparison of cycloalkanes

1968 ◽  
Vol 46 (20) ◽  
pp. 3235-3240 ◽  
Author(s):  
Gordon R. Freeman ◽  
E. Diane Stover
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Bond Cleavage ◽  
Open Chain ◽  
Methyl Substitution ◽  
Product Yields ◽  
Total Ionization ◽  
Gamma Radiolysis ◽  
G Value

The initial yields of the major products of the gamma radiolysis of liquid methylcyclopentane (MCP) at 25° are: G(H2) = 4.2, G(1-methylcyclopentene plus methylenecyclopentane) = 2.7, G(3- plus 4-methyl-cyclopentene) = 1.0, G(open chain hexene) = 1.0, and G(bimethylcyclopentyl) = 0.9. The effects of scavengers on the product yields are reported and the mechanism is discussed.The liquid phase radiolytic decompositions of cyclohexane (CH), methylcyclohexane (MCH), cyclopentane (CP), and MCP are compared. The net amount of C—C bond cleavage is much greater in the five-membered than in the six-membered rings. Methyl substitution on the ring reduces G(H2) by about one unit, mainly because of the formation of a type of ion (QH+) that does not yield hydrogen when neutralized by an electron. The QH+ type ions are formed in MCH and MCP, but not in CH and CP. In all the systems, another type of ion (N+) that does not yield hydrogen when neutralized by an electron is formed with a G value of about unity. The type of ion (PH+) that does yield hydrogen when neutralized by an electron has a G value of 3.4 in CH and CP, but only 2.0 in MCP. It is concluded that G(total ionization) is in the vicinity of 4.4 in the liquid compounds, virtually the same as the gas phase values.

scholarly journals Photoluminescence of CdSe/ZnS quantum dots in nematic liquid crystals in electric fields

2018 ◽  
Vol 9 ◽  
pp. 1544-1549 ◽  
Author(s):  
Margarita A Kurochkina ◽  
Elena A Konshina ◽  
Daria Khmelevskaia
Keyword(s):  
Quantum Dots ◽  
Liquid Crystals ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Dielectric Anisotropy ◽  
Vertical Position ◽  
Decay Times ◽  
Pl Intensity

We have experimentally investigated the effect of the reorientation of a nematic liquid crystal (LC) in an electric field on the photoluminescence (PL) of CdSe/ZnS semiconductor quantum dots (QDs). To the LC with positive dielectric anisotropy, 1 wt % QDs with a core diameter of 5 nm was added. We compared the change of PL intensity and decay times of QDs in LC cells with initially planar or vertically orientated molecules, i.e., in active or passive LC matrices. The PL intensity of the QDs increases four-fold in the active LC matrix and only 1.6-fold in the passive LC matrix without reorientation of the LC molecules. With increasing electric field strength, the quenching of QDs luminescence occurred in the active LC matrix, while the PL intensity did not change in the passive LC matrix. The change in the decay time with increasing electric field strength was similar to the behavior of the PL intensity. The observed buildup in the QDs luminescence can be associated with the transfer of energy from LC molecules to QDs. In a confocal microscope, we observed the increase of particle size and the redistribution of particles in the active LC matrix with the change of the electric field strength. At the same time, no significant changes occurred in the passive LC matrix. With the reorientation of LC molecules from the planar in vertical position in the LC active matrix, quenching of QD luminescence and an increase of the ion current took place simultaneously. The obtained results are interesting for controlling the PL intensity of semiconductor QDs in liquid crystals by the application of electric fields.

scholarly journals Electric fields and double layers in plasmas

1987 ◽  
Vol 5 (2) ◽  
pp. 233-255 ◽  
Author(s):  
Nagendra Singh ◽  
H. Thiemann ◽  
R. W. Schunk
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Electric Fields ◽  
Sheet Thickness ◽  
High Density ◽  
Effective Length ◽  
Double Layers ◽  
Low Density ◽  
Ambient Magnetic Field ◽  
Cold Plasmas

Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamic features of the double layers are discussed. These features, as seen in simulations, laboratory experiments and theory, indicate that double layers and the currents through them undergo slow oscillations, which are determined by the ion transit time across an effective length of the system in which the double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations have been considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields (parallel to an ambient magnetic field) and double layers in an expanding plasma are discussed.

EXCITED STATES OF ACETYLENE AND THEIR ROLE IN PYROLYSIS

1958 ◽  
Vol 36 (1) ◽  
pp. 131-136 ◽  
Author(s):  
G. J. Minkoff
Keyword(s):  
Liquid Phase ◽  
Induction Period ◽  
Gas Phase ◽  
Recent Work ◽  
Excited States ◽  
Trans Configuration ◽  
Detailed Mechanism ◽  
Vinyl Polymerization ◽  
Gas Phase Polymerization ◽  
Kinetic Form

Previous theories of acetylene pyrolysis are reviewed in the light of recent work by Minkoff, Newitt, and Rutledge. It is shown that the relatively large rates observed at the beginning of the induction period do not agree with mechanisms involving the intervention of comparatively stable dimers. The required kinetic form is obtained, however, if a triplet diradical is produced on the surface in a bimolecular process, followed by gas phase polymerization, with some chain ending on the surface. The detailed mechanism closely resembles Flory's scheme for liquid phase vinyl polymerization. The shape of the radical is discussed, and it is suggested that the trans-configuration leads to polymerization, while the cis facilitates dehydrogenation.

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