A study of the ground and excited states of Al3 and Al3(-). II. Computational analysis of the 488 nm anion photoelectron spectrum and a reconsideration of the Al3 bond dissociation energy.

摘要: Computational results are reported for the ground and low-lying excited electronic states of Al(3)(-) Al(3) compared with available spectroscopic data. In agreement previous assignments, six photodetachment transitions observed in vibrationally resolved 488 nm photoelectron spectrum assigned as arising from X (1)A(1) (')((1)A(1)) (3)B(2) accessing (2)A(1)(')((2)A(1)) (2)A(2)(")((2)B(1)), (4)A(2), (2)B(2) (with C(2v) labels D(3h) parentheses). Geometries vibrational frequencies obtained by PBE0 hybrid density functional calculations using 6-311+G(3d2f) basis set energies calculated coupled cluster theory single double excitations a quasiperturbative treatment connected triple (CCSD(T)) aug-cc-pVxZ {x=D, T, Q} sets exponential extrapolation to complete limit good experiment. Franck-Condon spectra harmonic approximation, either Sharp-Rosenstock-Chen method which includes Duschinsky rotation or parallel-mode Hutchisson method, also agree well spectra. Possible assignments higher-energy bands previously UV suggested. Descriptions transition between terms natural bond order (NBO) analyses total electron difference distributions discussed. A reinterpretation structure resonant two-photon ionization is proposed, supports its original assignment (2)A(1)(') state, giving an dissociation energy, D(0)(Al(2)-Al), 2.403+/-0.001 eV. With this reduction 0.3 eV currently recommended value, present Al(3), Al(3)(-), Al(3)(+) consistent experimental