An earlier study [Chem. Phys. Lett. 1, 619 (1968)] concluded that the reaction H + O(3) ? OH + O(2) forms OH predominantly in the highest accessible vibrational levels, upsilon = 8 and 9. We have extended this earlier work (1) by using fourier transform spectroscopy which is capable of giving more precise values for the relative vibrational populations at low intensities, (2) by recording emission down to lower background pressures (1 x 10(-4) Torr), and (3) by treating the vessel walls so as to remove OHdagger (vibrationally excited OH in it ground (2)II electronic state) more effectively. This involved using a room temperature vessel coated with silica gel. Under these conditions (provided that the values available for the radiational lifetime of OHdagger are correct) vibrational relaxation of OHdagger should have been largely arrested. We conclude that the relative rate constants for formation of OHdagger in levels upsilon are k(upsilon = 6) < 0.4, k(upsilon = 7) asymptotically equal to 0.4, k(upsilon = 8) asymptotically equal to 0.8, and k(upsilon = 9) = 1.00.

The intensity of the emitted visible radiation is studied for the temperature range 830–890 °K. (AIP)

Infra-red chemiluminescence from the reaction Hf Cl2 +HClt+ Cl (HClt is vibrationally excited HC1 in its ground electronic state) has been examined with improved resolution at roughly two orders of magnitude lower HCl pressure than heretofore. Under stationary state conditions the rotators in vibrational levels 1 to 4 appear to be in thermal equilibrium (135175°C) up to J = 7.There is, however, an excess of rotators in rotational levels J = 9, 10, 11, . . . of v = 2, 3 and 4 (v = 1 was not measured to J>9). This could be the residue of an even greater rotational excess present in the newly-formed HC1. The stationary state vibrational distribution is markedly non-Boltzmann, being characterized by " temperatures " ranging from 8000 to 2930°K. Relative rates of reaction, Rv, into the various vibrational levels of HClt, have been calculated from the observed stationary state distribution, in several ways. The rate of reaction is always found to be greater into lower vibrational levels, the rate into u = 3 being approximately 35 times that into u = 5.

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

On the theory of translational energy distributions of product molecules of molecular beam reactions involving transient complexes. II TIlE I.eUers to the Editor section is subdivided into f01lr categories entitled Communications, .Votes, Comments, and Errata. The textual material of eaclt I.eUer is lililited to 950 "-,ords minus the follo7C'illg: (a) 200 ,,'ords for euclt (/verage-si~ed figure; (b) 50 ,:'ords for eaclt displayed equation; (c) 7 ,cords for each line of table including headings and I/Ori~ontlll rulings. Proof ,,-,ill be sellt to authors.