Differential cross sections for state specific reactive scattering of Na–SF6→NaF–SF5

Abstract

Absolute elastic differential electron scattering cross sections in the intermediate energy region. III. SF6 and UF6 Double-differential cross sections for the interaction of Na͑3 2 S͒ and Na͑3 2 P͒ with SF 6 have been measured in crossed beam experiments for center of mass collision energies between 0.25 and 1.75 eV. In comparison with recently reported experiments the reaction with vibrationally excited SF 6 is found to be more effective than the one with electronically excited Na. Results from an ab initio CASSCF calculation with Na in the ground state and the 3 P state are presented. The experimental findings and the results from the calculation lead us to two different models for the reaction in the ground state and the excited state: While the well known harpooning model is verified for the ground state the reactive collisions with excited Na are mediated by nonadiabatic ͑nonreactive͒ transitions to the ground state surface. For these transitions the vibrational motion of SF 6 is much more efficient than the relative motion in the collision.

Mesospheric Removal of Very Long-Lived Greenhouse Gases SF6 and CFC-115 by Metal Reactions, Lyman-α Photolysis, and Electron Attachment

“…R1 has also been studied in a diffusion flame, from which a rate constant of k 1 (523 K) = 3.6 × 10 -11 cm 3 molecule -1 s -1 was obtained (see Table 1 in Gislason and Kwei 25 ), which is a factor of 2.3 larger than in the present study. Düren et al 26 …”

Electron‐Driven Self‐Assembly of Salt Nanocrystals in Liquid Helium

“…Our reasoning is as follows. First, an activation barrier of 250 meV is known for the Na+SF 6 →NaF+SF 5 reaction in the gas phase[ 23 ] which will be insurmountable at 0.4 K without an additional source of energy. Second, any reaction between Na n and (SF 6 ) m will be highly exothermic and requires the dissipation of many eV of excess energy.…”

Experimentelle Untersuchungen zur reaktiven Streuung laserangeregter Teilchen

“…Über das reaktive Streusystem Na » SF 6 ist, im wesentlichen aus vorher an der hier verwendeten Apparatur erzielten Ergebnissen [44,55,79,80,17,18,14], einiges bekannt. Daher soll zunächst eine Zusammenfassung bisheriger Erkenntnisse erfolgen, um dann die spezifischen, in dieser Arbeit behandelten Fragestellungen abzugrenzen.…”

“…Für den Vergleich der Systeme Na(3S)-SF 6 und Na(3P)-SF 6 stellt sich weiterhin die Frage, ob die elektronische Anregung Einfluß auf den Charakter der Reaktion hat. Schließlich gilt zumindest für den Beginn des Stoßprozesses eine andere Potentialfläche, die im Falle von Na(3P)-SF 6 für eine kollineare Konfiguration (s. Abschnitt 5.5, [14]) einen verhältnismäßig tiefen Potentialtopf aufweist.…”

“…Für Na-SF 6 wurden für den Grundzustand und den ersten elektronisch angeregten Zustand des Gesamtsystems von B. HEUMANN [14] mit quantenchemischen Methoden Potentialflächen berechnet (Abb. 5.21 und 5.22).…”