The emission spectroscopy of AlD in the visible region: experimental and theoretical investigations

The emission spectrum of the AlD isotopologue has been experimentally studied using Fourier transform spectroscopy in the 17, 700 − 28, 500 cm−1 spectral region. AlD molecules were produced within an aluminum hollowcathode lamp with two anodes in the presence of 2.7 Torr of Ne and 0.2 Torr of ND3. The observed bands have been assigned to the A1Π−X1Σ + (0 − 0, 1 and 1−0, 1, 2, 3 bands) and C1Σ +−A1Π (0−0 and 1−1 bands) transitions. In total, more than 450 rotational frequencies were measured with an absolute accuracy of about 0.002 cm−1 . The current data have been combined with available measurements of the pure rotational lines by Halfen and Ziurys [Astrophys J 2010;713:520-523] and with the ro-vibrational bands by White et al. [J Chem Phys 1993;99:8371-8378] to provide improved spectroscopic constants of the X1Σ +, A1Π and C1Σ + states of AlD. These results match closely theoretical values obtained using a new set of ab initio potentials calculated with a spin-orbit Hamiltonian.