Geometry of the CaOCH3 radical from isotope effects in the transition

Isotopic study of the transition of calcium monomethoxide using laser excitation and population depletion spectroscopy

“…Our spectra of the e A 2 E-e X 2 A 1 transition [1,4] were regular and all the lines were assigned for each of the four isotopologues. There was an unexplained 10 cm À1 isotope shift associated with deuterium substitution, which had also been noted in the low-resolution 0022-2852/$ -see front matter Ó 2008 Elsevier Inc. All rights reserved.…”

“…Fits treated each isotopologue independently, with ground state parameters constrained to the values established from the e A-e X analysis (see Ref. [1]), using a symmetric rotor model [6]. The Q branch data, which were not completely resolved in the spectra, were not included in any of the fits.…”

“…8 and 9, both the spin rotation splitting and the effective A values appear to be well behaved for K = 2 and 3 but are dependent on K for K = 0 and 1. The ground state energies were calculated from the constants determined from the e A-e X spectra [1] and A was fixed at 2.6895 cm À1 . From the graph, Fig.…”

“…In a recent publication [1], we examined the rotational structure of the e A 2 E-e X 2 A 1 transition of four isotopic species of calcium monomethoxide. From the resulting molecular parameters, we were able to derive the structure of the molecule in the ground and excited states.…”

“…The spectra were obtained using laser induced fluorescence with a laser ablation source under the same conditions used to obtain the e A-e X spectrum [1,4], the only difference being that the ring dye laser was scanned in the 17 675-17 693 cm À1 region. However, because the spectra of the deuteride species were more complex than expected (and defied assignment), we have also employed a population depletion optical optical double resonance (OODR) technique, described below, to assign the transitions.…”