Rovibronic Spectroscopy of Sympathetically Cooled CaH.

We measure the rovibronic transitions X Σ, v″ = 0, J″ → A Σ, v' = 0-3, J' of CaH and obtain rotational constants for the A Σ state. The spectrum is obtained using two-photon photodissociation of CaH cotrapped with Doppler cooled Ca. The excitation is driven by a mode-locked, frequency-doubled Ti:Sapph laser, which is then pulse shaped to narrow the spectral bandwidth.

Reassigning the CaH 1Σ → 2Σ vibronic transition with CaD.

We observe vibronic transitions in CaD between the 1Σ and 2Σ electronic states by resonance enhanced multiphoton photodissociation spectroscopy in a Coulomb crystal. The vibronic transitions are compared with previous measurements on CaH. The result is a revised assignment of the CaH vibronic levels and a disagreement with multi-state-complete-active-space second-order perturbation theory theoretical calculations by approximately 700 cm.

Vibronic Spectroscopy of Sympathetically Cooled CaH.

We report the measurement of the 1 Σ→2 Σ transition of CaH by resonance-enhanced photodissociation of CaH that is co-trapped with laser-cooled Ca . We observe four resonances that we assign to transitions from the vibrational v=0 ground state to the v'=1-4 excited states based on theoretical predictions. A simple theoretical model that assumes instantaneous dissociation after resonant excitation yields results in good agreement with the observed spectral features except for the unobserved v'=0 peak.

The beryllium pentamer: trailing an uneven sequence of dissociation energies.

Recent high-resolution spectroscopic studies by Merritt, Bondybey, and Heaven (Science 2009, 324, 1548) have heightened the anticipation that small beryllium clusters will soon be observed in the laboratory. Beryllium clusters are important discrete models for the theoretical study of metals. The trigonal bipyramidal Be(5) molecule is studied using high-level coupled cluster methods.