Optical-optical double resonance spectrum of Na 2: Observation of atomic and molecular ultraviolet emission

Abstract

We have observed both atomic and molecular ultraviolet fluorescence following optical-optical double-resonance excitation in Na 2. The atomic fluorescence has been assigned as 4p-3s emission at 330 nm. Four possible excitation schemes are considered to account for these observations. All involve the near-degenerate (6) 1Σ g + and (5) 1Σ u + potentials of Na 2, which correlate to the atomic 3s+5s configuration and possess interesting double minima at very long range. The experimental and theoretical evidence points strongly to a route via the long-lived (2) 1Σ g + state.