Gas Phase Kinetics of H+H+H2→2H2

Three-body recombination of hydrogen during primordial star formation

“…In practice, measurements of the dissociation of molecular hydrogen by H, reaction , or the inverse reaction , are more difficult to perform in the laboratory than the corresponding reactions and with H 2 . At low temperatures (up to room temperature), the rate coefficient for reaction was measured directly, by means of a flow tube, by Ham, Trainor & Kaufman (1970) and Cohen & Westberg (1983) based their recommended rate coefficient for this reaction on the measurements of Ham et al However, the extrapolation of these measurements to much higher temperatures, relevant here, remains uncertain. Furthermore, shock tube measurements at higher temperatures (up to a few thousand Kelvin), such as those of Jacobs et al (1967), relate directly to the collisional dissociation of H 2 , rather than its formation through three‐body recombination.…”

Pulsed Laval nozzle study of the kinetics of OH with unsaturated hydrocarbons at very low temperatures

“…The Smith et al rule 2 therefore suggests that the former two, but not the latter, should be fast at very low temperatures. 90 Maintaining a thermalised environment at very low temperatures for kinetic studies has been achieved using either cryogenic cooling 9 or a supersonic gas expansion, and the methods have been extensively reviewed 4,10,11 . Cryogenic cooling of the reaction cell and using collisions with a buffer 95 gas to cool the reagents has been widely used but suffers from the major drawback that many reagent gases, or particularly the precursors used to generate free-radicals, condense or adsorb onto walls of the chamber.…”

Der Einfluss von Wasser und Wasserstoffbrücken auf Reaktionen in Lavaldüsenexpansionen

“…Untersuchung von Gasphasenreaktionen bei tiefen Temperaturen verwenden im Wesentlichen zwei verschiedene Techniken: Kryogene Kühlung einer Flusszelle und Abkühlung eines Gasgemisches durch adiabatische Expansion. Verschiedene Studien verdeutlichen den Nutzen der kryogenen Kühlung für Messungen bis hinab zu einer Temperatur von 77 K unter Verwendung von flüssigem Stickstoff als Kühlmittel [19][20][21][22][23]. Die Methode leidet jedoch unter der starken Limitierung durch die bei tiefen Temperaturen einsetzende Kondensation der Reaktanden an der Reaktorwand nach Überschreiten des Sättigungsdampfdrucks [24].…”