Absorption spectroscopy of AlO including photodissociation

Photodissociation of AlO may be important for the aluminium chemistry in various astrophysical regions. The photodissociation cross sections and rates of AlO were investigated over the temperature range from 0 to 15000 K in this work. Firstly, the state-resolved cross sections at the wavelength of 50 − 5000 nm for transitions from the ground and first excited states were calculated using ab initio potential energy curves and transition dipole moments. The temperature-dependent cross sections were then obtained by assuming a Boltzmann distribution to describe the population of the initial state. Several common radiation fields (interstellar, solar and blackbody radiation field) were selected as the radiation fields, and then the photodissociation rates in different radiation fields were obtained. The photodissociation rates in all studied radiation fields exhibit a positive correlation with increasing temperature. This finding indicates that the total photodissociation rates are sensitive to the temperature. In addition, the photodissociation rates in the solar radiation field are higher than those in the interstellar radiation fields, indicating that photodissociation rate is associated with the type of radiation field in which the molecule is exposed. The calculated photodissociation cross sections and rates of AlO are useful to investigate the chemical evolution of the aluminum element in the interstellar environment.