Line Shape and f Value in the OH 2Σ+ — 2Π Transition

Abstract

Line shape and f value in the ultraviolet transition 2Σ+—2Π of OH have been studied by the curve of growth method, and rough direct measurements of line width have been made. The lines Q16, P16, R16, Q216, and S16 fit a curve of growth indicating a collision broadening width of 0.02±0.02 cm-1 at 2600°K and 1 atmos in flame gases of the approximate composition O2 60%, H2O 20%, and CO2 20%. For the Q16 line, the f value is (11.7±4)×10-4. This corresponds to a radiative lifetime for the free molecule of 5.5×10-7 sec, in excellent agreement with the earlier work of Oldenberg. Brief discussions are given of theoretical limitations on the use of the curve of growth, and of the qualitative factors to be considered in explaining the observed line width.