Multiple Ionization of Cesium and Barium by Successive Electron Impacts

1971 ◽  
Vol 49 (5) ◽  
pp. 585-593 ◽  
Author(s):  
P. A. Redhead ◽  
C. P. Gopalaraman
Keyword(s):  
Energy Levels ◽  
Ion Source ◽  
Ionization Potentials ◽  
Ion Currents ◽  
Extrapolation Methods ◽  
Trapped Ion ◽  
Multiply Charged ◽  
Multiple Ionization ◽  
Combined Uncertainty ◽  
Potential Curves

The electron energy dependence of the multiply-charged ion currents of cesium and barium (up to Cs10+ and Ba10+) has been measured in a trapped-ion source mass spectrometer. Approximate values of the higher ionization potentials have been measured which agree with the values predicted by extrapolation methods, to within the combined uncertainty of the experimental and extrapolation methods (~5 V), except for the ionization potential of Ba9+. Improved estimates of higher ionization potentials of ions with atomic number 53–56 have been obtained by the extrapolation method. The energy levels of some long-lived metastable states of Cs and Ba ions were estimated from the measured appearance potential curves.

Multiple ionization in carbon monoxide by successive electron impacts

1969 ◽  
Vol 47 (22) ◽  
pp. 2449-2457 ◽  
Author(s):  
P. A. Redhead
Keyword(s):  
Reasonable Agreement ◽  
Energy Levels ◽  
Ion Sources ◽  
Mass Spectrometers ◽  
Trapped Ion ◽  
Appearance Potential ◽  
Multiply Charged ◽  
Multiple Ionization ◽  
Charged Ions ◽  
Potential Curves

Appearance potential curves for the multiply-charged ions of carbon and oxygen (up to C4+ and O6+ for electron energies less than 200 eV) have been measured in two mass spectrometers fitted with trapped-ion sources. Trapping of the C+ and O+ ions is not as efficient as for ions produced without dissociation because of the initial kinetic energies of the dissociatively produced ions. The predominant collision sequences involve the formation of CO+ as the first step rather than the dissociative ionization of CO. Ionization potentials estimated from measured appearance potential curves are in agreement with spectroscopically determined values. Most of the other breaks that were repeatedly observed in the appearance potential curves are in reasonable agreement with energy-limiting steps in the collision sequences corresponding to transitions between spectroscopically known energy levels of the ions. Two observed transitions (in O4+ and O5+ appearance potential curves) cannot be explained in terms of spectroscopically known energy levels and may result from highly-excited, long-lived states of O2+ and O4+, respectively. The threshold of the C4+ appearance potential curve indicates the existence of a metastable state of C3+ not previously observed.

Sequential-impact mass spectrometry; pressure dependence of ion currents from trapped-ion sources

1970 ◽  
Vol 48 (16) ◽  
pp. 1906-1916 ◽  
Author(s):  
P. A. Redhead
Keyword(s):  
Cross Sections ◽  
Ion Source ◽  
High Electron ◽  
Ion Currents ◽  
Trapped Ion ◽  
Positive Ions ◽  
Ion Escape ◽  
Electron Current Density ◽  
12 Steps ◽  
Ion Collision

Positive ions can be trapped by electron space–charge fields in the ion-source of a mass spectrometer resulting in electron–ion collision sequences. With high electron current density (~0.5 A cm−2) and potential barriers to prevent ion escape along the axis of the electron beam, the trapping time can be increased sufficiently so that collision sequences with as many as 12 steps are observed.A simple model of the behavior of a trapped-ion source has been developed and solutions for the ion currents as a function of pressure obtained. The predictions of the model are compared with experimental results for neon and argon and approximate agreement obtained. Approximate values of cross sections for ionization and excitation of ions can be obtained by fitting the predictions of the model to the measured ion current vs. pressure curves.

MULTIPLE IONIZATION OF THE RARE GASES BY SUCCESSIVE ELECTRON IMPACTS (0–250 eV): I. APPEARANCE POTENTIALS AND METASTABLE ION FORMATION

1967 ◽  
Vol 45 (5) ◽  
pp. 1791-1812 ◽  
Author(s):  
P. A. Redhead
Keyword(s):  
Electron Emission ◽  
Ion Source ◽  
Metastable States ◽  
Rare Gases ◽  
Trapped Ion ◽  
Sharp Maximum ◽  
Multiple Ionization ◽  
Metastable Ions ◽  
Charge Multiplicity ◽  
Charged Ions

Multiple ionization of the rare gases has been examined in a mass spectrometer with a trapped-ion source. Ions with charge multiplicity up to n = 2 (He), n = 5 (Ne), n = 6 (Ar), n = 7 (Kr), and n = 10 (Xe) were observed with electron energies less than 250 eV. For He and Ne the thresholds agree with spectroscopic values of the ionization potentials, indicating a process of the form eN/ee(N + 1), where N represents an ion of charge multiplicity n. For Ar, Kr, and Xe, processes involving metastable states of the ion are also observed, eN/eNm; eNm/ee(N + 1). The estimated energies of the metastable levels of Ar+, Kr+, Xe+, Ar2+, and Xe2+ are in agreement with spectroscopic values. The energies of the metastable states of Ar+, Kr+, and Xe+ are in agreement with measurements of Auger electron emission from metals by metastable ions. The metastable levels estimated for the more highly charged ions (up to n = 5 for Ar, n = 6 for Kr, and n = 8 for Xe) have not been observed previously. The excitation functions of the metastable levels of Ar+, Kr+, and Xe+ are very similar and show a very sharp maximum near threshold.

scholarly journals Intercombination Transitions between Levels X1Σg+ and A 3Πu in C2

1987 ◽  
Vol 120 ◽  
pp. 103-105
Author(s):  
J. Le Bourlot ◽  
E. Roueff
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Wave Functions ◽  
Spin Orbit Coupling ◽  
Energy Matrix ◽  
First Order ◽  
Emission Transition ◽  
Intercombination Transition ◽  
The One ◽  
Potential Curves

We present a new calculation of intercombination transition probabilities between levels X1Σg+ and a 3Πu of the C2 molecule. Starting from experimental energy levels, we calculate RKR potential curves using Leroy's Near Dissociation Expansion (NDE) method; these curves give us wave functions for all levels of interest. We then compute the energy matrix for the four lowest states of C2, taking into account Spin-Orbit coupling between a 3Πu and A 1Πu on the one hand and X 1Σ+g and b 3Σg− on the other. First order wave functions are then derived by diagonalization. Einstein emission transition probabilities of the Intercombination lines are finally obtained.

Negative-Ion Implantation

1994 ◽  
Vol 354 ◽  
Author(s):  
Junzo Ishikawa
Keyword(s):  
Ion Implantation ◽  
Negative Ions ◽  
Ion Source ◽  
Negative Ion ◽  
Rf Plasma ◽  
Ion Currents ◽  
Promising Technique ◽  
Surface Charging ◽  
Silicon Carbon ◽  
A Charge

AbstractNegative-ion implantation is a promising technique for forthcoming ULSI (more than 256 M bits) fabrication and TFT (for color LCD) fabrication, since the surface charging voltage of insulated electrodes or insulators implanted by negative ions is found to saturate within so few as several volts, no breakdown of insulators would be expected without a charge neutralizer in these fabrication processes. Scatter-less negative-ion implantation into powders is also possible. For this purpose an rf-plasma-sputter type heavy negative-ion source was developed, which can deliver several milliamperes of various kinds of negative ion currents such as boron, phosphor, silicon, carbon, copper, oxygen, etc. A medium current negative-ion implanter with a small version of this type of ion source has been developed.

scholarly journals Upgrading the ECR ion source within FAMA

2018 ◽  
Vol 33 (1) ◽  
pp. 47-52
Author(s):  
Andrey Efremov ◽  
Sergey Bogomolov ◽  
Vladimir Bekhterev ◽  
Aleksandar Dobrosavljevic ◽  
Nebojsa Neskovic ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Ion Beam ◽  
Ion Source ◽  
Vacuum System ◽  
Multiply Charged Ions ◽  
Inlet System ◽  
Multiply Charged ◽  
Microwave System ◽  
Beam Currents ◽  
Charged Ions

Recent upgrading of the Facility for Modification and Analysis of Materials with Ion Beams - FAMA, in the Laboratory of Physics of the Vinca Institute of Nuclear Sciences, included the modernization of its electron cyclotron resonance ion source. Since the old ion source was being extensively used for more than 15 years for production of multiply charged ions from gases and solid substances, its complete reconstruction was needed. The main goal was to reconstruct its plasma and injection chambers and magnetic structure, and thus intensify the production of multiply charged ions. Also, it was decided to refurbish its major subsystems - the vacuum system, the microwave system, the gas inlet system, the solid substance inlet system, and the control system. All these improvements have resulted in a substantial increase of ion beam currents, especially in the case of high charge states, with the operation of the ion source proven to be stable and reproducible.

Multiply-Charged Metal Ion Source for Cyclotron

1980 ◽  
Vol 19 (9) ◽  
pp. 1745-1750 ◽  
Author(s):  
Kumio Ikegami ◽  
Tadashi Kageyama ◽  
Isao Kohno
Keyword(s):  
Metal Ion ◽  
Ion Source ◽  
Multiply Charged
Sign in / Sign up

Export Citation Format

Share Document