Theoretical and experimental research on excimer like (N-2)(2) dimer: potential energy curves and spectra

Theoretical ab initio calculations for a number of symmetry groups of (N-2) (2) dimer are performed with an emphasis on the intermolecular distance 1.2 less than or equal to R less than or equal to 2.5 Angstrom. Except for the D-2h group, the ground and excited state potential energy curves of most o f the symmetry groups are repulsive in this region. The theoretical results indicated that there exists an excimer like electric dipole transition bet ween the excited singlet states a(1)B(2g) and a(1)B(3u) of the D-2h symmetr y group. The oscillator strength and theoretical spectra are calculated. Ex perimentally observed emission spectra for the excimer-like (N-2)(2) dimer is found to be in good agreement with our theoretical calculations. (C) 200 0 Elsevier Science B.V. All rights reserved.