Zhang Shu-Dong

An ab initio investigation of the low-lying electronic states of BeH

Potential energy curves (PECs) for the ground state (X2Σ+) and the four excited electronic states (A2Π, B2Π, C2Σ+, 4Π) of a BeH molecule are calculated using the multi-configuration reference single and double excited configuration interaction (MRCI) approach in combination with the aug-cc-pVTZ basis sets. The calculation covers the internuclear distance ranging from 0.07 nm to 0.70 nm, and the equilibrium bond length Re and the vertical excited energy Te are determined directly. It is evident that the X2Σ+, A2Π, B2Π, C2Σ+ states are bound and 4Π is a repulsive excited state. With the potentials, all of the vibrational levels and inertial rotation constants are predicted when the rotational quantum number J is set to be equal to zero (J = 0) by numerically solving the radial Schrodinger equation of nuclear motion. Then the spectroscopic data are obtained including the rotation coupling constant ωe, the anharmonic constant ωexe, the equilibrium rotation constant Be, and the vibration-rotation coupling constant αe. These values are compared with the theoretical and experimental results currently available, showing that they are in agreement with each other.

One-colour resonant two-photon ionization spectrum of the 1-fluoronaphthalene dimer and ab initio calculation

The one-colour resonant two-photon ionization (R2PI) spectrum of the 1-∞uoronaphthalene (1FN) dimer has been studied in the wavelength range of 304 to 322 nm by using a supersonic molecular beam and time-of-∞ight mass spectrometry. Compared with the original band 0 0 (at 313.8 nm) of the S1 ˆ S0 transition of the 1FN monomer, a red-shifted band was observed in the 1FN dimer spectrum at about 315 nm with a relatively large linewidth, nearly 2 nm. Based on the consideration of inductive efiect and ab initio calculations, this red-shifted band is assigned to the flrst electronic excited transition of the 1FN dimer. A possible geometric structure of the 1FN dimer is also obtained with calculations that the two 1FN molecules are combined through two hydrogen bonds which are formed between the hydrogen atom of a molecule and the ∞uorine atom of a neighbouring molecule. A time-dependent calculation was also carried out and the results are consistent with the experimental data.