Frequency-modulated laser absorption spectroscopy of CH (X^2Π → A^2 Δ)

Analysis of measured high-resolution doublet rovibronic spectra and related line lists of 12CH and 16OH

“…83BrBr 74 Calculated data only. 88LyWo 85 No transitions data provided. 88NeBrEv 86 Only Hamiltonian parameters are provided.…”

“…Other sources claimed to have measured highly-accurate and well-resolved transitions, but the accuracy of the transition data provided is not even close to the claimed uncertainty. Another case is the example of 88LyWo, 85 who report successful measurement of the A 2 Δ–X 2 Π R1(5.5) transition with an uncertainty of 0.0002 cm −1 but with no actual transition wavenumber given.…”

“…1 for the states covered in this study). To do this we analyze the experimental spectroscopic data available for the parent 12 CH 6,9–15,20,40,51,62–105 and 16 OH 8,21,31,38,41,43–47,52,53,106–158 isotopologues, using the Hamiltonian-free M arvel procedure, 1–5 and obtain high-accuracy empirical rovibronic energy levels with well-defined uncertainties. The empirical energy levels obtained allow the critical assessment of line lists 9,51–53 created previously for the two radicals.…”

6 Infrared emission spectroscopy

“…This potential advantage of emission spectroscopy for the detection of ions and free radicals is well known is the visible and near-UV regions. For example, the violet emission from the CH radical (A 2 D3X 2 P) is readily seen by eye in a £ame 19 but the measurement of the A 2 D2X 2 P absorption 20 is much more dif¢cult. This emission advantage persists into the infrared region.…”