Rate Constants and H-Atom Product Yields for the Reactions of O(¹D) Atoms with Ethane and Acetylene from 50 to 296 K

Abstract

The gas phase reactions of atomic oxygen in its first excited state with ethane and acetylene have been investigated in a continuous supersonic flow reactor over the temperature range from 50 to 296 K. O(D) atoms were produced by the pulsed laser photolysis of ozone at 266 nm. Two different types of experiments, kinetics measurements and H-atom product yield determinations, were performed by detecting O(D) atoms and H(S) atoms, respectively, by vacuum ultraviolet laser-induced fluorescence. The measured rate constants are in agreement with previous work at room temperature, and little or no temperature dependence was observed as the temperature was decreased to 50 K. H-atom yields were found to be independent of temperature for the reaction of O(D) with ethane. These product yields are discussed in the context of earlier dynamics measurements at higher temperature. Due to the influence of secondary reactions, no H-atom yields could be obtained for the reaction of O(D) with acetylene.

A kinetic study of the N(2D) + C2H4 reaction at low temperature

“…36,37 Modifications to the original design have allowed us to implement a detection method based on tunable narrowband radiation in the vacuum ultraviolet (VUV) wavelength range; a region where many strong electronic transitions of atomic radicals are located. In this way, it has been possible to follow the kinetics of both ground (C( 3 P), [38][39][40] H( 2 S) 38,[40][41][42][43][44][45][46][47][48][49] and D( 2 S), 40,49,50 ) and excited (O( 1 D) 45,48,[51][52][53][54][55] and N( 2 D) 56,22,23 ) state atoms at low temperature. As the electronic quenching of N( 2 D) is slow with both Ar 57 and N2, 14 both of these could be used as Laval nozzle carrier gases.…”

Rate constants for the N(2D) + C2H2 reaction over the 50–296 K temperature range

“…The measurements reported here were performed using a supersonic flow (Laval nozzle) apparatus, which has been described in previous work. [25][26][27] Later studies report the various modifications applied to the original experiment to allow narrowband tunable vacuum ultraviolet radiation to be generated for the detection of several atomic species in their ground and excited electronic states (C( 3 P), [28][29][30] H( 2 S) 28,[30][31][32][33][34][35][36][37][38] and D( 2 S), 30,39 O( 1 D) 35,38,[40][41][42][43][44] and N( 2 D) 15,22 ). Experiments were performed using argon and nitrogen based Laval nozzles during the present work as N( 2 D) atoms are only slowly quenched by both of these gases.…”

A low temperature investigation of the N(2D) + CH4, C2H6 and C3H8 reactions

“…The experiments performed in this study employed an existing continuous supersonic flow reactor whose main features have been described previously. [28][29][30] Further modifications to the apparatus allowing the generation of narrowband tunable radiation in the vacuum ultraviolet wavelength range for the detection of atomic radicals in ground and excited electronic states are reported in later work (C( 3 P), [31][32][33] H( 2 S) 31,[33][34][35][36][37][38][39][40][41] and D( 2 S), 33,42 O( 1 D), 38,41,[43][44][45][46][47] and N( 2 D)). 6 During this work, both Ar and N2 were used as carrier gases as they result in only slow quenching of N( 2 D) atoms.…”

“…Similarly, although the CN and O( 1 D) products of the C + NO reaction react readily with saturated hydrocarbon molecules, 38,41,53 none of these processes are thought to lead to the formation of N( 2 D) atoms.…”