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Radiative recombination of N+O has been investigated by using this radiation as a highly specific light source for dissociation of NO. This direct proof of predissociation of NO(C 2Π) supports previous indirect evidence. Measurements of the rate of N2 production in the photodissociation lead to a rate coefficient for the process N+O ⇄ NO(C 2Π, v′ = 0) → NO(X 2Π, v″ = 0) + hν, kδ0,0 = (2.9 ± 0.5) × 10−18 cm3 sec−1 at 300°K. The total rate coefficient summed over v″ is (1.5 ± 0.4) × 10−17 cm3 sec.−1 When N and O concentrations are measured by titration, the recombination emission can be used as an absolute intensity standard (±20%) at 1900 Å.

The r-centroid concept, was proposed the in 1950s to permit factoring of the band strength integral Sυ',υ'' into the product of the Franck–Condon factor qυ',υ'', and of the square of the electronic transition moment Re (r), when taken at the r-centroid value of the internuclear separation, r = [Formula: see text]υ',υ'', which is the most likely value r at which the υ' « υ'' transition will occur. It has been much used since then in the interpretation of intensity measurements on many band systems of importance in astrophysics, atmospheric physics, space physics, and chemical physics to determine the variation of the electronic transition moment with internuclear separation, and thereby to derive band strengths, and other molecular transition probability parameters. It has been somewhat less used in recent years in the study of individual band systems, since the development of powerful computing facilities now allow for exact ab initio numerical studies to be made of individual molecules and their radiative transitions. Nevertheless the r-centroid concept, and some of its recent developments, provide much insight into the general systematics of diatomic molecular band systems and their spectra. This partly tutorial paper reviews the origins, properties, applications, and recent developments of the r-centroid concept. PACS No.: 33.70

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A fast converging iterative algorithm based on the Edlén1 refractive index formula has been developed. It uses corrections from the virial equation of state for air-water vapor mixtures2,3 and the recently revised refractive index of water vapor.4 Input parameters are barometric pressure, ambient temperature, relative humidity and carbon dioxide concentration. The default value of any parameter is its standard value. The program can perform single conversions or generate conversion tables for up to 6000 entries per batch.