Based on resonant two-photon ionization of 21Li3 with cw lasers and mass-selective detection of 21Li3+ ions by a quadrupole mass spectrometer, isotope-selective rotationally resolved spectra of vibronic bands in the electronic A 2E″←X2E′ system have been recorded. The complex but completely resolved spectra could be analyzed using optical-optical double resonance techniques in combination with accurate ab initio calculations which provide potential energy surfaces and rovibronic term values for both electronic states. A detailed comparison between experimental and theoretical results for the (v′s = 0, v′b = 0, v′a = 0)←(v″s = 0, v″b = 0, v″a = 0) band demonstrates excellent agreement. The coupling between pseudorotation and rotational motion is shown to produce complex level patterns which, however, can be accurately represented by an effective pseudo/rotation Hamiltonian in terms of rotational and coupling constants that directly provide structural information. For both electronic states the nuclear dynamics is adequately described as a motion on a single adiabatic potential surface with a geometric phase π for closed loops around the conical intersection at D3h geometries.
|Number of pages||18|
|Journal||Journal of Chemical Physics|
|State||Published - 1 Nov 2000|
ASJC Scopus subject areas
- Physics and Astronomy (all)
- Physical and Theoretical Chemistry