THE )[-A(3)SIGMA(-SIGMA(3)SIGMA(+)(G)[-A(3)SIGMA(+)(U) SYSTEMS OF AR-2()(U) AND (5)F)

Rotationally resolved transitions of the 5f pi (3) Pi(g)<--4s sigma a (3)Sigma(u)(+) and 5f sigma (3) Sigma(g)(+)<--4s sigma a (3)Sigma(u)() systems of Ar-2 have been observed by laser excitation spectroscopy in a pulsed corona discharge. These systems were previously observed a t lower resolution [D. J. Kane et al., J. Chem. Phys. 96, 6407 (1992)] with the system tentatively labeled nl lambda Pi(g)-a and subsequentl y assigned as 5f pi (3) Pi(g)-a on the basis of theoretical considerat ions [P. Duplaa and F. Spiegelmann, J. Chem. Phys. 105, 1500 (1996)]. Rotational analyses for the (0-0) and (0-1) bands of both systems rue presented and the upper states characterized. The (0-2) bands of the 5 f pi-a and 5f sigma-a transitions are observed also, as are the (0-0) band of 4f delta (3) Delta(g)-a (3) Sigma(u)(+) and the (1-0) and (2-0 ) bands of 5f pi-a, but with rotational structures insufficiently deve loped to permit analysis. The linewidths of the rotational lines of th e above bands are much broader than are the lines of the 7p sigma (3) Sigma(u)(+)-a system previously analyzed [C. M. Herring et al., J. Che m. Phys. 101, 4561 (1994)], presumably because of increased lifetime b roadening. Several spectral features observed in the 5f pi (3) Pi(g) b and structures that are not apparently compatible with this upper stat e assignment are discussed. (C) 1998 American Institute of Physics. [S 0021-9606(98)01611-0].