AN IMPROVED TECHNIQUE FOR THE OBSERVATION OF INFRARED CHEMILUMINESCENCE: RESOLVED INFRARED EMISSION OF OH ARISING FROM THE SYSTEM H + O₂

Abstract

A ~nultiple reflection apparatus for the observation of infrared chemiluminescence is described. By means of this apparatus infrared emission from the system H + 0 2 has been identified as being due to vibrationally excited OH radicals in levels v = 1, 2, and 3 of the ground electro~iic state. The resolved infrared spectrum of the OH fundamental has been observed for, the first time without interference from other emission. The most likely source of excited OH is the reaction H + 1302 --r O H t + OH. The vibrational 'temperature' of O H t (vibrationally excited OH in its ground electronic state) in our system is in the region of T v = 2240" I<. These findings are discussed in relation to I<rassovsky's suggestion that reaction between H and 0 2 could account for the Meinel hydroxyl bands in the night sky. INTRODUCTIONInfrared emission arising from the gaseous system 1-1 + 0 2 , a t rooln temperature, has been reported by Cashion and Polanyi (1). The emission consisted principally of three broad unresolved bands extending from 3400 to 4000 cm-I, with maxima a t 3600, 3730, and 3830 cnz-' (2.78, 2.68, and 2.61 p ) . The illtensity of the first peak could be varied, by varying reagent flows, independently of the other two, indicating that it was due to a separate emitting species. I t was thought that this might be the hydroxyl radical, OH, with vo for v = 1 -+ v = 0 a t 3570 cm-I (2). The other two maxima were of constant relative intensity and it was suggested that these might be either the Q and R branches of the V Q 0-H stretclling fundamental of water (vo a t 3755.8 (3)) or alternatively the 0-H stretching fundamental of the H o e radical. In either case the P branch ~vould presu~nably be lnasked by the other emission, attributed to the hydrosyl radical.Prior to the \vorlc described above, AlIcI<inley, Garvin, and Boudart (4) had observed visible and photographic-infrared regions of the spectrum fro111 OH formed in the reaction 1-1 + 0 3 . They failed, however, to observe any elllission whatever from the system 1-1 + 02. They concluded, in agreement with suggestions made by Bates and Nicolet ( 5 ) , and by I-Ierzberg (6), that the reaction H + 0 2 was responsible for the Meinel hydroxyl bands in the airglow (7). This result later received further support from a careful reexa~nination of the visible and photographic-infrared emission (8) and recently an examination of the infrared emission (9).I<rassovsl;~7 (lo), however, has put forward the view (criticized by Bates and hIoiseiwitsch (11)) that the evidence concerning the Meinel hydroxyl bands is inore consistent with the formati011 of escited 01-1 in a reaction + O?. He considered that this reaction, to be sufficiently exothermic, would have to involve vibratio~lallji excited 0 2 . At first sight the results of Cashion and Polanyi (1) might appear to lend support to Krassovsliy's view. The present investigation was undertalcen in the hope of clarifying this point. I n order to do this it mas necessary in the first place to establish that the slrstem 1-...

Use of a mathematical model and experiments to determine the mechanism and rate constant of hydroxyl chemiluminescence from oxygen atom attack on ethylene

“…The comparable reaction with H atoms, reaction 3, would also be potentially important in an O2 containing system and is known to produce OH(u < 4). 32 To produce the observed absolute concentration of OH(u = 9) from these lower vibrational levels requires a rate constant for ( 5 ) exceeding gas kinetic. Upper limit calculations to the pumping rate via vibration-vibration exchange can be made as illustrated in Table I11 by applying a gas kinetic rate constant.…”

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

“…The mirrors were supported from the outer wall of the vessel. 35 These mirrors, designed for use in the 2-5 p, range, were front-surface coated with gold.…”

Energy distribution among reaction products. Part 1.—The reaction atomic hydrogen plus molecular chlorine

“…The apparatus has been described previously. 16 In the present work, in addition to coating the reaction vessel with phosphoric acid, a phosphoric-coated Pyrex lining was placed inside the vessel in the hope of decreasing the loss of H atoms at the wall. The four discharge tubes were drawn down to 3 mm at their tips.…”

“…An apparatus with 120 times the reaction volume of that used in our earlier work on H+Clz, and with internal mirrors to collect the radiation, has already been described in connection with an investigation of the system H + 02. 16 A preliminary investigation of the reactions H + Cl2 and H + NOCl in this apparatus 17 showed that at -10-2 mm Hg total pressure ( N 10-1 times the total pressure used in the earlier work) the stationary distribution of HClt in the reaction vessel was markedly non-Boltzmann. Emission previously observed from the highest vibrational levels was no longer observed at the low pressure.…”