THE BOND-LENGTH OF VAR+

Rotational analysis of the B-5 Pi(1)-X-5 Sigma(+) electronic transitio n in isolated VAr+ has been performed. The zero-point level of the gro und-state of the ion is found to have a bond length of r(0) = 2.64 +/- 0.02 Angstrom and a binding energy of D-0'' = 2982 +/- 10 cm(-1) with respect to ground-state atomic fragments. The excited (B (5) Pi(1)) s tate of the ion is significantly more repulsive than the ground state and is found to have an r(0) = 2.91 +/- 0.02 Angstrom, and a diabatic dissociation energy of D-0' = 1361 +/- 10 cm(-1). The vibrational stru cture of the excited state shows frequency and anharmonicity of omega( c)' = 90.4 cm(-1), and omega(e)x(e)' = 1.56 cm(-1), respectively, and a rotation-vibration coupling constant of alpha(c) = (2.06 +/- 0.05) x 10(-3) cm(-1). (C) 1998 Elsevier Science B.V. All rights reserved.