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.

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 of mercury by successive electron impacts

1968 ◽  
Vol 46 (17) ◽  
pp. 1905-1913 ◽  
Author(s):  
P. A. Redhead ◽  
S. Feser
Keyword(s):  
High Current Density ◽  
Ionization Probability ◽  
Ion Current ◽  
High Current ◽  
Mercury Ions ◽  
Multiply Charged ◽  
Multiple Ionization ◽  
Charge Multiplicity ◽  
Slow Electrons ◽  
Charged Ions

Mercury ions of charge multiplicity up to n = 9 have been formed by repeated collisions of slow electrons (less than 150 eV) with ions trapped in an electron beam of high current density (~5 × 10−2 A cm−2). Ion current is observed at electron energies below the ionization potential for all multiply charged ions up to n = 8 and is ascribed to collision sequences involving metastable states of the ions (eN/eNm/ee(N + 1), where N represents an ion of charge multiplicity n). All the breaks observed in the ionization probability curves for [Formula: see text] can be explained in terms of collision sequences involving spectroscopically known metastable levels as limiting steps. Measured ionization potentials of the highly ionized species up to n = 9 are in reasonable agreement with extrapolation of spectroscopic values.

scholarly journals Thermodynamic properties of nonideal plasmas with multiple ionization and Coulomb and hard-core interactions

1990 ◽  
Vol 8 (4) ◽  
pp. 753-762 ◽  
Author(s):  
Torsten Kahlbaum ◽  
Andreas Förster
Keyword(s):  
Thermodynamic Properties ◽  
Hard Core ◽  
Mass Action ◽  
Free Electrons ◽  
Heavy Particles ◽  
Multiply Charged ◽  
Multiple Ionization ◽  
Nonideal Plasmas ◽  
Charged Ions ◽  
Mean Charge

We present a theoretical approach to the thermodynamic properties of nonideal plasmas consisting of neutral atoms, multiply charged ions, and free electrons. Starting with the free energy, we describe the ionization equilibrium of this system by a coupled set of mass action laws (Saha equations). Our model of interaction takes into account Coulomb forces between all charged particles and hard-core forces between all heavy particles and the electrons. The influence of multiple ionization and different interaction parts on plasma composition, mean charge, and equation of state is discussed for xenon. Finally, we show the potential occurrence of the plasma phase transition.

Sign in / Sign up

Export Citation Format

Share Document