scholarly journals Dissociative electron attachment in alcohols and ethers: Its relatioship to Rydberg states

2008 ◽  
Vol 6 (1) ◽  
pp. 77-88
Author(s):  
Bogdan Ibanescu ◽  
Michael Allan
Keyword(s):  
Excited State ◽  
Feshbach Resonance ◽  
Rydberg States ◽  
Electron Attachment ◽  
Dft Method ◽  
Negative Ion ◽  
Feshbach Resonances ◽  
Free Electrons ◽  
Potential Surfaces ◽  
Positive Ions

A dramatic difference was observed in the reactivity of alcohols and ethers toward free electrons. Whereas the lowest core-excited state of the negative ion - a 2(n,3s2) Feshbach resonance - of the alcohols readily dissociates by losing a hydrogen atom, ethers show no observable signal from this resonance. This difference in reactivity has a parallel in the anomalous shapes and energies of the parent states of the Feshbach resonances, the 1(n,3s) Rydberg states of the neutral alcohols and ethers. We explained this anomaly by means of potential surfaces of the alcohols and ethers calculated using the TD-DFT method as a function of the dissociation coordinate. The lowest excited state of alcohols was found to be repulsive, as a consequence of an avoided crossing between the 3s and 3px Rydberg configurations, whereas a barrier to dissociation was found in the ethers. Rydberg-valence mixing and avoided crossings are decisive in determining the shapes of the potential surfaces. It is concluded that the reactivities of alcohols and ethers toward free electrons are rationalized by assuming that the potential surfaces of the daughter Feshbach resonances closely follow those of the parent Rydberg states, i.e., the lowest Feshbach resonance is repulsive, but a barrier occurs in ethers. The potential surfaces of both the Rydberg states and the Feshbach resonances thus differ dramatically from the non-dissociative surface of the grandparent 2(n-1) positive ions, despite the nominally non-bonding character of the Rydberg electrons.

Numerical Simulation of Leakage Current on Conductive Insulator Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 9487-9492
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Leakage Current ◽  
Method Of Lines ◽  
Electron Attachment ◽  
Negative Ions ◽  
Conduction Current ◽  
Insulator Surface ◽  
Finite Difference Approximations ◽  
Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

Note on radiationless transitions involving three-body collisions

1936 ◽  
Vol 32 (3) ◽  
pp. 482-485 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Continuous Spectrum ◽  
Negative Ions ◽  
Bound State ◽  
Excess Energy ◽  
Negative Ion ◽  
Positive Ions ◽  
Continuous State ◽  
Direct Formation ◽  
Three Body ◽  
Positive Ion

When an electron makes a transition from a continuous state to a bound state, for example in the case of neutralization of a positive ion or formation of a negative ion, its excess energy must be disposed of in some way. It is usually given off as radiation. In the case of neutralization of positive ions the radiation forms the well-known continuous spectrum. No such spectrum due to the direct formation of negative ions has, however, been observed. This process has been fully discussed in a recent paper by Massey and Smith. It is shown that in this case the spectrum would be difficult to observe.

Chaos in positive ion–negative ion magnetized plasmas

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Samiran Ghosh ◽  
Biplab Maity ◽  
Swarup Poria
Keyword(s):  
Nonlinear Wave ◽  
Low Frequency ◽  
Negative Ions ◽  
Dynamical Behaviour ◽  
Negative Ion ◽  
Sound Waves ◽  
Weakly Nonlinear ◽  
Positive Ions ◽  
Experimental Parameters ◽  
Map Analysis

The dynamical behaviour of weakly nonlinear, low-frequency sound waves are investigated in a plasma composed of only positive and negative ions incorporating the effects of a weak external uniform magnetic field. In the plasma model the mass (temperature) of the positive ions is smaller (larger) than that of the negative ions. The dynamics of the nonlinear wave is shown to be governed by a novel nonlinear equation. The stationary plane wave (analytical and numerical) nonlinear analysis on the basis of experimental parameters reveals that the nonlinear wave does have quasi-periodic and chaotic solutions. The Poincarè return map analysis confirms these observed complex structures.

Complete negative-ion conversion of halogen atoms and positive ions in surface scattering from KI(100)

1996 ◽  
Vol 54 (3) ◽  
pp. 2486-2488 ◽  
Author(s):  
H. Winter ◽  
A. Mertens ◽  
C. Auth ◽  
A. G. Borisov
Keyword(s):  
Negative Ion ◽  
Surface Scattering ◽  
Halogen Atoms ◽  
Positive Ions

scholarly journals Characterization of ions at Alpine waterfalls

2011 ◽  
Vol 11 (9) ◽  
pp. 25297-25325 ◽  
Author(s):  
P. Kolarž ◽  
M. Gaisberger ◽  
P. Madl ◽  
W. Hofmann ◽  
M. Ritter ◽  
...  
Keyword(s):  
Negative Ion ◽  
Moderate Increase ◽  
Field Campaign ◽  
Ion Gradients ◽  
Austrian Alps ◽  
Positive Ions ◽  
Ion Detector

Abstract. During a three-year field campaign of measuring waterfall generated ions, we monitored five different waterfalls in the Austrian Alps. Most measurements were performed at the Krimml waterfall (Salzburg), which is the biggest and most visited one in Europe and the Gartl waterfall (Mölltal, Carinthia). Smallest ion sizes (0.9–2 nm) were measured with a cylindrical air ion detector (CDI-06) while ion sizes from 5.5 to 350 nm were measured using a modified Grimm SMPS aerosol spectrometer. Measurements showed high negative ion gradients nearby waterfalls whereas positive ions showed only a moderate increase. The most abundant sizes of nano-sized and sub-micrometer ions measured were at 2 nm and of the larger and heavier ones at 120 nm.

Sign in / Sign up

Export Citation Format

Share Document