Negative ions in thymine and 5-bromouracil produced by low energy electrons

2003 ◽  
Vol 226 (3) ◽  
pp. 397-403 ◽  
Author(s):  
R. Abouaf ◽  
J. Pommier ◽  
H. Dunet
Keyword(s):  
Negative Ions ◽  
Low Energy ◽  
Low Energy Electrons

Desorption of negative ions on metallic samples by very low energy electrons

1983 ◽  
Vol 126 (1-3) ◽  
pp. A126
Author(s):  
M. Bernheim ◽  
M. Chaintreau ◽  
R. Dennebouy ◽  
G. Slodzian
Keyword(s):  
Negative Ions ◽  
Low Energy ◽  
Low Energy Electrons

POSSIBLE "HOT" MOLECULE DESORPTION BY ELECTRON STIMULATED DECOMPOSITION OF DIHALOETHANES ON Cu(111)

1994 ◽  
Vol 01 (04) ◽  
pp. 535-538 ◽  
Author(s):  
S. TURTON ◽  
M. KADODWALA ◽  
ROBERT G. JONES
Keyword(s):  
Electron Capture ◽  
Photoelectron Spectroscopy ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Negative Ions ◽  
Low Energy ◽  
First Order ◽  
Sufficient Energy ◽  
Low Energy Electrons ◽  
Low Energy Electron

The desorption of ethene from physisorbed 1, 2-dichloroethane (DCE) and 1-bromo-2-chloroethane (BCE) on Cu(111) has been observed on irradiating the surface with electrons. The techniques used were low energy electron diffraction (LEED), Auger electron spectroscopy (AES), ultraviolet photoelectron spectroscopy (UPS), and mass spectrometric detection of the desorbed species. At 110 K physisorbed DCE and BCE underwent electron capture from low energy (<1 eV ) electrons in the secondary electron yield of the surface followed by decomposition and desorption of ethene alone. The decomposition was found to be first order in the surface coverage of the physisorbed DCE/BCE. No other molecular species desorbed from the surface, a stoichiometric amount of chemisorbed halogen was deposited and no carbon was detectable at the end of the desorption. The formation of the negative ions of these molecules by electron capture of low energy electrons in the secondary electron emission from the surface and the possible dynamics by which the negative ions undergo decomposition leaving the ethene product with sufficient energy to desorb, are discussed.

Desorption of negative ions on metallic samples by very low energy electrons

1983 ◽  
Vol 126 (1-3) ◽  
pp. 610-617 ◽  
Author(s):  
M. Bernheim ◽  
M. Chaintreau ◽  
R. Dennebouy ◽  
G. Slodzian
Keyword(s):  
Negative Ions ◽  
Low Energy ◽  
Low Energy Electrons

The Attachment of Low-Energy Electrons to Dicyanogen in the Gas Phase

1985 ◽  
Vol 38 (6) ◽  
pp. 967 ◽  
Author(s):  
PW Harland ◽  
BJ McIntosh
Keyword(s):  
Gas Phase ◽  
Negative Ions ◽  
Low Energy ◽  
Electron Gun ◽  
Translational Energy ◽  
Ion Formation ◽  
Collision Chamber ◽  
Low Energy Electrons ◽  
Balance Analysis ◽  
Energy Balance Analysis

The negative ions C-, CN- and C2N- formed by the dissociative resonance attachment of low-energy electrons to dicyanogen in the gas phase have been studied over the electron impact energy range from 0 to 15 eV. The formation of the CN- ion was studied by using a 'monochromatic' electron gun and the translational energy of the ion measured as a function of the electron energy across the dissociative resonance capture curve. An energy balance analysis for CN- ion formation has been used to propose the electron capture processes and to construct a potential energy diagram (for C-C internuclear separation) for CN- ion formation. The molecular ion, C2N2-, has been shown to result from the associative resonance attachment of thermalized electrons scattered from the collision chamber surfaces and to exhibit an autodetachment lifetime in the microsecond timerange.

Collision-induced dissociations of negative ions. α-Dicarbonyl parent negative ions

1984 ◽  
Vol 37 (7) ◽  
pp. 1447 ◽  
Author(s):  
JH Bowie ◽  
T Blumenthal ◽  
MH Laffer ◽  
S Janposri ◽  
GE Gream
Keyword(s):  
Carbon Monoxide ◽  
Carbonyl Group ◽  
Negative Ions ◽  
Low Energy ◽  
Dicarbonyl Compounds ◽  
Low Energy Electrons

α-Dicarbonyl compounds form stable parent negative ions by capture of low-energy electrons. The parent negative ions undergo a variety of collision induced dissociations, the most characteristic being β cleavage to a carbonyl group, i.e. see diagram in paperCyclic α-dicarbonyl parent negative ions may also eliminate molecules of carbon monoxide, for example the fragmentations M- → [M-(R + CO)]- M- →[M - (R-2CO)]- and M- → [M-2CO]- occur in a number of cases.

Temperature dependencies of negative ions formation by capture of low-energy electrons for some typical MALDI matrices

2003 ◽  
Vol 227 (2) ◽  
pp. 259-272 ◽  
Author(s):  
S.A. Pshenichnyuk ◽  
N.L. Asfandiarov ◽  
V.S. Fal’ko ◽  
V.G. Lukin
Keyword(s):  
Negative Ions ◽  
Low Energy ◽  
Low Energy Electrons

Transfer optics for high spatial resolution electron spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 666-667
Author(s):  
G. G. Hembree ◽  
Luo Chuan Hong ◽  
P.A. Bennett ◽  
J.A. Venables
Keyword(s):  
Magnetic Field ◽  
Scanning Transmission Electron Microscope ◽  
Low Energy ◽  
Objective Lens ◽  
State University ◽  
Arizona State University ◽  
Initial Field ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Low Energy Electrons

A new field emission scanning transmission electron microscope has been constructed for the NSF HREM facility at Arizona State University. The microscope is to be used for studies of surfaces, and incorporates several surface-related features, including provision for analysis of secondary and Auger electrons; these electrons are collected through the objective lens from either side of the sample, using the parallelizing action of the magnetic field. This collimates all the low energy electrons, which spiral in the high magnetic field. Given an initial field Bi∼1T, and a final (parallelizing) field Bf∼0.01T, all electrons emerge into a cone of semi-angle θf≤6°. The main practical problem in the way of using this well collimated beam of low energy (0-2keV) electrons is that it is travelling along the path of the (100keV) probing electron beam. To collect and analyze them, they must be deflected off the beam path with minimal effect on the probe position.

Preincubation with Sn-complexes causes intensive intracellular retention of 99mTc in thyroid cells in vitro

2012 ◽  
Vol 51 (05) ◽  
pp. 179-185 ◽  
Author(s):  
M. Wendisch ◽  
D. Aurich ◽  
R. Runge ◽  
R. Freudenberg ◽  
J. Kotzerke ◽  
...  
Keyword(s):  
Cell Model ◽  
Low Energy ◽  
Thyroid Cells ◽  
Low Energy Electrons ◽  
A Cell ◽  
Vitro Model ◽  
Uptake Studies ◽  
Radiobiological Effects ◽  
Radioactivity Retention

SummaryTechnetium radiopharmaceuticals are well established in nuclear medicine. Besides its well-known gamma radiation, 99mTc emits an average of five Auger and internal conversion electrons per decay. The biological toxicity of these low-energy, high-LET (linear energy transfer) emissions is a controversial subject. One aim of this study was to estimate in a cell model how much 99mTc can be present in exposed cells and which radiobiological effects could be estimated in 99mTc-overloaded cells. Methods: Sodium iodine symporter (NIS)- positive thyroid cells were used. 99mTc-uptake studies were performed after preincubation with a non-radioactive (cold) stannous pyro - phosphate kit solution or as a standard 99mTc pyrophosphate kit preparation or with pure pertechnetate solution. Survival curves were analyzed from colony-forming assays. Results: Preincubation with stannous complexes causes irreversible intracellular radioactivity retention of 99mTc and is followed by further pertechnetate influx to an unexpectedly high 99mTc level. The uptake of 99mTc pertechnetate in NIS-positive cells can be modified using stannous pyrophosphate from 3–5% to >80%. The maximum possible cellular uptake of 99mTc was 90 Bq/cell. Compared with nearly pure extracellular irradiation from routine 99mTc complexes, cell survival was reduced by 3–4 orders of magnitude after preincubation with stannous pyrophosphate. Conclusions: Intra cellular 99mTc retention is related to reduced survival, which is most likely mediated by the emission of low-energy electrons. Our findings show that the described experiments constitute a simple and useful in vitro model for radiobiological investigations in a cell model.

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