Franck-Condon simulation of the single-vibronic-level emission spectra of HPCI/DPCI and the chemiluminescence spectrum of HPCI,including anharmonicity

摘要

Restricted-spin coupled-cluster single-double plus perturbative triple excitation [RCCSD(T)] potential energy functions (PEFs) were calculated for the X~2A" and A ~2A' states of HPCI employing the augmented correlation-consistent polarized-valence-quadruple-zeta (aug-cc-pVQZ) basis set.Further geometry optimization calculations were carried out on both electronic states of HPCI at the RCCSD(T) level with all electron and quasirelativistic effective core potential basis sets of better than the aug-cc-pVQZ quality,and also including some core electrons,in order to obtain more reliable geometrical parameters and relative electronic energy of the two states.Anharmonic vibrational wave functions of the two states of HPCI and DPC1,and Franck-Condon (FC) factors of the A~2A'-X~2A" transition were computed employing the RCCSD(T)/aug-cc-pVQZ PEFs.Calculated FC factors with allowance for Duschinsky rotation and anharmonicity were used to simulate the single-vibronic-level (SVL) emission spectra of HPCI and DPC1 reported by Brandon et al [J.Chem.Phys.119,2037 (2003)] and the chemiluminescence spectrum reported by Bramwell et al.[Chem.Phys.Lett.331,483 (2000)].Comparison between simulated and observed SVL emission spectra gives the experimentally derived equilibrium geometry of the A ~2A ' state of HPCI of r,(PCl)=2.0035+-0.0015 A,theta_e =16.08+-0.60deg,and r_e(HP)=1.4063+-0.0015 A via the iterative Franck-Condon analysis procedure.Comparison between simulated and observed chemiluminescence spectra confirms that the vibrational population distribution of the A ~2A' state of HPCI is non-Boltzmann,as proposed by Baraille et al.[Chem.Phys.289,263 (2003)].