Eur. Phys. J. D 55, 549-555 (2009)
https://doi.org/10.1140/epjd/e2009-00253-y

Emission spectroscopy of the A¹Π–X¹Σ⁺ system of AlH ^*

Atomic and Molecular Physics Laboratory, Institute of Physics University of Rzeszów, 35-959 Rzeszów, Poland

Corresponding author: ^a szajna@univ.rzeszow.pl

Received: 4 February 2009
Revised: 26 May 2009
Published online: 26 September 2009

Abstract

The high-resolution emission spectrum of the A¹ Π–X¹Σ⁺ transition of AlH was observed in the 18 000–25 000 cm^-1 spectral region using a conventional spectroscopic technique. The AlH molecules were excited in an Al hollow-cathode lamp filled with a mixture of Ne carried gas and a trace amount of NH₃. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total 163 transition wave numbers belonging to six bands (0-0,1 and 1-0,1,2,3) were precisely measured and rotationally analysed. In the final fit the present data have been combined with available high-resolution measurements of the vibration-rotation bands by White et al. [J. Chem. Phys. 99, 8371 (1993)]. This procedure enabled extracting molecular constants for the A¹ Π and X¹ Σ⁺ states of AlH. A very slight local perturbation has been discovered in the v=1 vibration level of the A¹ Π state at J=5. This was probably caused by the interaction with the a³Π state.