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Apparate und Methoden / Elektronenaffinitat / Massenspektroskopie / Molekiilstruktur / Zwischenmolekulare WechselwirkungenResonance dissociative attachment of monoenergetic electrons in the energy range from 0.0 eV to 10 eV to CCl,, CHCI,, CH,CI, and CHJ1 has been studied using a trochoidal electron monochromator and a quadrupole mass filter. The following fragment negative ions as a function of electron impact energy could be observed: C1-. CI;, CCl; and CCI; from CCI,; CI-, HCI; and CCl; from CHCI,; CI-, Cl; and CC1; from CHZCI, and CI-and CH,Cl-from CH,CI. -The attachment cross section decreases rapidly as H replaces CI. Appearance potentials for the negative fragments and for c c l 3 and CC1, electron affinities in the limit of the excess energy are given.

Resonance dissociative electron attachment and ion pair formation following electron impact have been studied in the energy range from 0 – 20 eV. The translational excess energies of the negative ion fragments have been determined using a time‐of‐flight technique in combination with mass analysis in a quadrupole mass filter. Compared with other halogenated methanes, the resonances in CHF3, CH2F2, and CH3F leading to negative fragments appear at considerable higher energies. The experimental results indicate that those resonances are associated with multiple fragmentation reactions.

Apparate und Methoden 1 Elektronenaflinitat 1 Elektronenanlagerung / MassenspektroskopieMit Hilfe eines Trochoidal-Elektronenmonochromators (AE rz 0.13 eV) und eines Quadrupol-Massenfilters wird die energieselektive Fragmentierung von CF3CI, CFzClz und CFC13 im Bereich niedriger Elektronenenergien (0 -10 eV) untersucht. Innerhalb einer Anzahl verschiedener negativer Fragmente ist die iiberaus intensive Bildung von C1-aus CFCI,das bereits bei 0.0 eV entstehtbesonders auKillig. Die hohen Bildungsquerschnitte machen deutlich, daD bereits niederenergetische Elektronen, ganz im Gegensatz zu Photonen, die chemisch sehr stabilen Gase zu dissoziieren vermogen. Es wird diskutiert, ob dieser Effekt die troposphirischen Lebensdauern der Halogenmethane beeinfluot.The fragmentation of CF,CI, CF2CIz, and CFCI, under low-energy (0-10 eV) electron impact has been investigated using a trochoidal electron monochromator (AE z 0.13 eV) and a quadrupole mass spectrometer. Among various negative fragments the CI--ion from CFCI, is by far the most abundant. It is observed at 0.0eV. The high yield of production clearly shows that low-energy electrons are much more disruptive in their impacts with these molecules than are photons. The influence of this effect concerning the tropospheric lifetime of the halocarbons will be discussed.