Reference Label Details
Coxon 1976J. A. Coxon and D. A. Ramsay, Can. J. Phys. 54, 1034-1042 (1976)
The A 2Pii - X 2Pii Band System of ClO: Reinvestigation of the Absorption Spectrum
note ClOCoxon 1976 observed transitions A 2Pi3/2 -> X 2Pi3/2, v'=2-25, v"=0, and A 2Pi1/2 -> X 2Pi1/2, v'=2,4,8, v"=1 and v'=2, v"=2 in 35ClO. They extract nu00 by 'stripping' off rotational terms expressed in both states by F1(2Pi3/2,v) = Bv1(J+1/2)^2 - Dv(J+1/2)^4 and F2(2Pi1/2,v) = Bv2(J+1/2)^2 - Dv(J+1/2)^4 +- peff(J+1/2), where peff accounts for lambda-doubling (negligible for F1 and approximately symmetric for F2). (The -Omega^2*B term is obviously contained in the n00 value.) From the n00 values, they extract limits using long-term properties as per LeRoy. The observed v00 for A 2Pi3/2 -> X 2Pi3/2, v'=25, v"=0 38021.06 cm-1. Depending on whether they use a fifth-order fit or sixth-order fit, they obtain extrapolated values for DeltaG'(v+1/2) of 15.75, 9.50, 4.98, 2.04, and 0.47 cm-1, or 15.15, 8.53, 3.80, and 1.00 cm-1. From these, they obtain limits of 38054.02 or 38049.54 cm-1. The dissociation limit of ClO A 2Pi is known to be Cl(2P3/2) + O(1D) from Durie 1958. Adopting the mean value of the two limits, and subtracting the term value of 1D relative to 3P2 in O, they obtain D0(ClO) = 22184 +- 3 cm-1. However, this needs to be corrected for the F1 term, since it refers to the rotationless v"=0 level of X 2Pi3/2. Also, there is a very small (and inconsequential) discrepancy between stated limits and the extrapolated DeltaG'(v+1/2) gaps. Adding these to the observed nu00 = 38021.06 cm-1 for A 2Pi3/2 -> X 2Pi3/2, v'=25, v"=0, one obtains 38053.80 and 38049.54 cm-1, with an average of 38051.67 (+- 2.13) cm-1. Subtracting the O(1D) term of 15867.862 cm-1 from NIST Atomic Web produces 22183.81 cm-1. The F1 term for J=3/2, calculated using their formulas and B01 = 0.619773 cm-1, is 2.479 cm-1. This produces a D0(35ClO) = 22181.33 +- 3 cm-1, where we keep their original uncertainty.
note ClOaD0(ClO) is corrected from 35 Cl to average Cl atomic weight of 35.4527 by adding 0.96 cm-1. The correction has been obtained by comparing ZPEs (including the Y00 term), which were estimated for the natural isotopic composition by applying standard isotopic relationships to the spectroscopic constants given by Huber 1979. This approach neglects possible electronic isoptopic shifts.