Characterisation Of The B(3)Sigma(+), V=0 State And Its Interaction With The A(1)Pi State In Aluminium Monofluoride

Recently, we determined the detailed energy level structure of the X-1 Sigma(+), A(1)Pi and a(3)Pi states of AlF that are relevant to laser cooling and trapping experiments [Truppe et al., Phys. Rev. A. 100 (5), 052513 (2019)]. Here, we investigate the b(3)Sigma(+), v = 0 state of the AlF molecule. A rotationally resolved (1+2)-REMPI spectrum of the b(3)Sigma(+), v' = 0 <- a(3)Pi, v '' = 0 band is presented and the lifetime of the b(3)Sigma(+), v = 0 state is measured to be 190(2) ns. Hyperfine-resolved, laser-induced fluorescence spectra of the b(3)Sigma(+), v' = 0 <- X-1 Sigma(+), v '' = 1 and the b(3)Sigma(+), v' = 0 <- a(3)Pi, v '' = 0 bands are recorded to determine fine- and hyperfine structure parameters. The interaction between the b(3)Sigma(+), v = 0 and the nearby A(1)Pi state is studied and the magnitude of the spin-orbit coupling between the two electronic states is derived using three independent methods to give a consistent value of 10(1) cm(-1). The triplet character of the A state causes an A -> alpha loss from the main A-X laser cooling cycle below the 10(-6) level.[GRAPHICS].