Optically pumped gas laser using electronic transitions in the NaRb molecule

Laser superradiance was achieved for the first time as a result of an electronic transition in a diatomic heteronuclear molecule as a result of direct optical pumping. This superradiance was observed in the region of 670 nm due to a transition to the ground stated X ¹Σ ⁺ of the intermetallic alkali molecule NaRb pumped by radiation from a pulsed copper vapor laser (λ =510.6 nm).