Single- and double-ionization potentials of polycyclic aromatic hydrocarbons and fullerenes by photon and electron impact

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1060-1069 ◽  
Author(s):  
S. Tobita ◽  
S. Leach ◽  
H. W. Jochims ◽  
E. Rühl ◽  
E. Illenberger ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Synchrotron Radiation ◽  
Electron Impact ◽  
Aromatic Hydrocarbons ◽  
Double Ionization ◽  
Ionization Potentials ◽  
Electrostatic Model ◽  
Yield Curves ◽  
Multiple Ionization ◽  
Polycyclic Aromatic

Single- and double-ionization appearance potentials of 21 polycyclic aromatic hydrocarbons (PAHs) were determined by measurement of photoion yield curves using a synchrotron radiation source. Analogous measurements were made by electron impact on three PAHs. The origin of differences, of up to 4 eV, between appearance potentials for double ionization by photon and electron impact is discussed. The ratio of the double- to single-ionization potentials of PAHs was found to be 2.65 ± 0.06 for photon impact, significantly lower than for electron-impact and charge-stripping measurements. An electrostatic model, which considers that PAHs ionize like fragments of graphite, is applied to the PAHs studied and to data on the fullerenes C60 and C70. The validity and limitations of the model are discussed and its analytical and predictive propensities concerning multiple-ionization potentials and processes are demonstrated.

Ionization energies of multicharged fullerenes: Application and validity of an electrostatic model

2001 ◽  
Vol 79 (2-3) ◽  
pp. 501-517 ◽  
Author(s):  
S Leach
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Work Function ◽  
Aromatic Hydrocarbons ◽  
Simple Relation ◽  
Electrostatic Model ◽  
Small Particles ◽  
Ionization Energies ◽  
Theoretical Approaches ◽  
Polycyclic Aromatic ◽  
Experimental Values

A simple relation between the successive ionization energies of polycyclic aromatic hydrocarbons obtained in 1961 by Smith from a calculation of the work required to remove electrons in small particles, is extended here to the fullerene species Cnz+, n = 50–70, z = 1–5, and in some cases up to z = 8. Tests of the validity of the effective values of the parameters of the model, the work function and molecular capacitance, are given. The predicted ionization appearance energies are in excellent agreement with experimental values. A comparison is made between our model and other theoretical approaches to the calculation of the ionization energies of fullerenes. PACS Nos.: 31.20W, 33.80E, 35.20V

Polycyclic aromatic hydrocarbons: negative ion formation following low energy (0–15 eV) electron impact

1992 ◽  
Vol 161 (3) ◽  
pp. 501-508 ◽  
Author(s):  
Seiji Tobita ◽  
Martina Meinke ◽  
Eugen Illenberger ◽  
Loucas G. Christophorou ◽  
Helmut Baumgärtel ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Electron Impact ◽  
Aromatic Hydrocarbons ◽  
Low Energy ◽  
Negative Ion ◽  
Ion Formation ◽  
Polycyclic Aromatic
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