The ultraviolet spectrum of AlH has been investigated at high resolution between 42 000 and 45 000 cm-1 using a conventional spectroscopic technique. The AlH molecules were formed and excited in an aluminium hollow-cathode lamp with two anodes, filled with a mixture of Ne carried gas and a trace of NH3. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The 0-0, 1-1 and 1-2 bands of the C1??+-X1??+ transition have been identified and rotationally analyzed. The new data were elaborated with help of recent X1??+ state parameters reported by White et al. [J. Chem. Phys. 99 (1993) 8371-8378] and by Szajna and Zachwieja [Eur. Phys. J. D. 55 (2009) 549-555]. Determined constants of the excited C1??+ state include: Te = 44 675.3711(57) cm-1, ??e = 1575.3357(42) cm-1, ??exe = [125.5] cm-1, Be = 6.66804(32) cm-1, ??e = 0.55839(56) cm-1, De = 2.23(13) ?? 10-4 cm-1, ??e = 6.13(25) ?? 10-4 cm-1 and re = 1.613132(39) ??. The C1??+ state is found to be extensively perturbed in the v = 0 and 1 vibrational level at J = 20, 22 - 27 and J = 5 - 9, respectively. This was probably caused by the interaction with the vibrational levels of the outer minimum. ?? 2010 Elsevier Inc. All rights reserved.
Szajna, W., & Zachwieja, M. (2010). The emission spectrum of the C1??+-X1??+ system of AlH. Journal of Molecular Spectroscopy, 260(2), 130–134. https://doi.org/10.1016/j.jms.2010.02.004