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Absolute partial and total electron ionization cross sections for CCl4 from threshold up to 180 eV (1984)

Leiter, K. ; Stephan, K. ; Märk, E. ; [et al.]

Springer

Plasma chemistry and plasma processing 4 (1984), S. 235-249

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ISSN: 1572-8986

Keywords: Ionization cross section ; electron impact ; mass spectrometry

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology

Notes: Abstract Electron impact ionization of carbon tetrachloride was studied as a function of electron energy from threshold up to 180 eV. A double-focusing mass spectrometer system in combination with an improved electron impact ion source was used, alleviating the problems of ion extraction from the source and the transmission of the extracted ions through the mass spectrometer system. Absolute partial ionization cross sections for the occurrence of CCl 3 + , CCl 2 + , CCl+, Cl 2 + , Cl+, C+, CCl 3 2+ , and CCl 2 2+ have been determined. In addition, the total ionization cross-section function of CCl4 is reported and compared with theoretical predictions based on a classical binary encounter approximation. Using nth root extrapolation the following ionization energies of the doubly ionized fragment ions have been derived: AE(CCl 3 2+ )=30.4±0.3 eV; and AE (CCl 2 2+ )=31.8±0.3 eV. In accordance with theoretical predictions and previous results, no stable CCl 4 + has been detected, however, metastable dissociation processes CCl 4 + → CCl 3 + have been observed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00568978

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Study of clusters by mass spectrometry (1991)

Stamatović, A. S. ; Maerk, T. D.

New York, NY : Wiley-Blackwell

Rapid Communications in Mass Spectrometry 5 (1991), S. 51-57

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ISSN: 0951-4198

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Physics

Notes: A review of mass spectrometric methods used to study different kinds of clusters is presented. These methods have proved to be indispensable in the cluster field owing to their great flexibility, sensitivity and wide dynamic range. This reviews presents new mass spectrometric methods and techniques such as quadrupole analysers and RF lenses, different ion-trap geometries, time-of-flight (TOF) methods including the reflectron geometry). A variety of ionization methods, both for the production of positive and negative ions, with different amounts of released excess energy, are discussed in detail. Special attention is given to different degree of post-ionization fragmentaqtion and metastability of ions produced by the respective ionization methods. The ability to follow the metastable decay processes in rather different time-windows is also one of the salient features of the mass spectrometric methods reviewed here, involving both classical and new geometries. Detection of very large cluster ions by conventional methods is not always effective, and alternative methods like post-acceleration and using a conversion dynode in front of the multiplier will be included here. Moreover, mass spectrometric methods offer the possibility of producing beams of mass-selected cluster ions necessary for the study of a whole line of process like optical spectrometry, photodetachment, photofragmentation, photoionization, electron beam ionization, and charge-exchange processes. Examples of these processes are also discussed in this review.

Additional Material: 6 Ill.