title: Perturbation analysis of the υ = 6 level in the d3Δ state of CS based on its near-infrared absorption spectrum.
abstract: The spectrum of CS was recorded in the region of 12,086-12,630 cm(-1) by employing optical heterodyne concentration modulation laser absorption spectroscopy. Nearly 350 transitions were assigned to the (6, 0) band in the d(3)Δ-a(3)Π system of CS. The overtone transitions of the (12, 0) band in the a(3)Π(2)-a(3)Π(0) transition were first observed due to the perturbation interaction between d(3)Δ(1) and a(3)Π(2). The Λ doubling in the a(3)Π(1) state was also resolved at high rotational levels. The molecular constants of the a(3)Π (υ = 0) and d(3)Δ (υ = 6) levels and the perturbation parameters of the d(3)Δ (υ = 6) level were determined through nonlinear least-squares fitting using effective hamiltonians. The calculations of mixing fractions of the perturbed states were performed in order to obtain precise information on the perturbations of the d(3)Δ (υ = 6) levels. The mechanisms for perturbations of d(3)Δ (υ = 6) with the a(3)Π (υ = 12) and A(1)Π (υ = 1) levels, especially for the second-order perturbation, were discussed and explained according to first-order nondegenerate perturbation theory.
authors.affiliation: State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062, China.
authors.forename: Chuanliang
authors.initials: C
authors.lastname: Li
authors.forename: Lunhua
authors.initials: L
authors.lastname: Deng
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ling
authors.initials: L
authors.lastname: Wu
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Yang
authors.forename: Yangqin
authors.initials: Y
authors.lastname: Chen