jp036351s_si_001.pdf (118.96 kB)
Rotationally Resolved (1 + 1‘) Resonance-Enhanced Multiphoton Ionization (REMPI) of CaR (R = H, D) in Supersonic Beams: CaR X 2Σ+ (υ‘ ‘ = 0) → CaR* B 2Σ+ (υ‘ = 0, 1) → CaR+ X Σ+
journal contribution
posted on 2003-12-18, 00:00 authored by Khaled Gasmi, Reem M. Al-Tuwirqi, Stefan Skowronek, Helmut H. Telle, Angel González UreñaWe report on a laser-spectroscopic study of the CaH and CaD radicals in a supersonic beam, generated in a
reaction of laser-sputtered Ca atoms and a pulsed beam of H2 or D2, seeded in helium. The rotational levels
of the electronic ground-state X 2Σ+ (υ‘ ‘ = 0, N‘ ‘ ≤ 10) were probed by two-color resonance ionization mass
spectrometry(1 + 1‘) resonance-enhanced multiphonon ionization (REMPI)via the intermediate B 2Σ+
(υ‘ = 0, 1) rovibronic levels. Rotational constants for the B-state were derived, including the spin splitting
parameters γυ‘, which have been determined in the case of CaD for the first time: γ0 = −0.409(7) cm-1 and
γ1 = −0.398(8) cm-1 for CaD (B Σ+), and γ0 = −0.792(15) cm-1 and γ1 = −0.765(16) cm-1 for CaH (B
2Σ+). The comparison between the rotational level energies of the F1 and F2 spin substates of the two
isotopomers revealed the onset of perturbation in CaH B 2Σ+ (υ‘ = 0), at N‘ ≅ 0, by the presence of the
vibronic state A 2Π (υ‘ = 1). Although this perturbation is documented for υ‘ ≥ 1, it had not been previously
recognized for υ‘ = 0. The rotational populations observed in X 2Σ+ (υ‘ ‘ = 0) for the two isotopomers could
be associated with different average rotational temperature values for CaD and CaH: Trot = 52 (± 7) and Trot
= 85 (± 11) K, respectively.