Rate coefficients of the aluminium monoxide formation by radiative association

Abstract

Radiative association may be a key pathway for the formation of aluminium monoxide (AlO) in diffuse interstellar clouds, especially for the oxygen-rich asymptotic giant branch (AGB) stars. In this work, we investigated the radiative association of AlO by the collision of the aluminum and oxygen atoms in their electronic ground states, which is thought to be the most probable radiative association process. Firstly, the potential energy curves for twelve electronic states and the dipole moments between these states were calculated by the state-of-the-art ab initio methodology. Then the cross sections and rate coefficients for the radiative association of AlO were computed for the temperatures in the range of 10 - 10000 K. The total rate coefficients are of the order of 2.73 × 10−19 − 1.14 × 10−16 cm3s−1, and the A2Π → X2Σ+, 12Δ → A2Π, 12Π → X2Σ+ and 22Σ− → A2Π transitions play a key role. The calculated results can be used to investigate the chemical evolution of dust formation in the photospheres of the oxygen-rich AGB stars.

Formation of CO through C (2s 22p 2 3P) and O (2s 22p 4 3P) Radiative Association

“…For example, the cross section for the c 3 Π → a 3 Π transition rises rapidly at collision energies around 0.593 and 0.850 eV. Similar behavior can generally be found in other diatomic systems, such as the D 1 Δ → A 1 Π transition of MgO (Bai et al 2021), the 1 4 Σ g + → a 4 Σ u + transition of N 2 + (Qin et al 2021), and the 1 2 Δ → A 2 Π transition of AlO (Bai et al 2022). Subsequently, the cross sections for the A 1 Π → X 1 Σ + and B 1 Σ + → X 1 Σ + transitions dominate over the energy ranges of about 0.01-10 eV and 0.4-10 eV, respectively.…”

“…These theories and methods of radiative association for diatomic molecules and ions are well established and summarized in the work of Nyman et al (2015), and have been used for dealing with many diatomic molecules and ions, such as CO , PO (Andreazza et al 2016), SiO (Cairnie et al 2017), CS (Forrey et al 2018), CO + (Zámečníková et al 2020), MgO (Bai et al 2021), + N 2 (Qin et al 2021), AlO (Bai et al 2022), etc. In addition, recent developments in the theories and methods for radiative association include the Sturmian quantum kinetic theory (Forrey 2015), the surface-hopping model of spontaneous electronic transitions (Szabó & Gustafsson 2017), the extension of radiative association for local thermal equilibrium (Gustafsson & Forrey 2019), and the treatment of non-adiabatic couplings (Gustafsson 2020).…”

Stimulated radiative association of sodium and chlorine atoms and their ions in a coupled channel treatment

“…10 While the experimental investigations of radiative association are very difficult, 11 the theoretical studies have been plentiful in the last decades. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Little is known about the formation of NaCl. 26 In our previous work, making use of the detailed diabatic picture with coupling, we studied the spontaneous radiative association to form NaCl [27][28][29] and also the non-radiative charge transfer, i.e., chemiionisation and mutual neutralisation.…”

Formation of SiO+ through radiative association of Si+(3s23p 2Pu) and O(2s22p4 3Pg)

“…However, a great number of traditional theories and methods, including the classical method (Gustafsson 2013;Nyman et al 2015;Kathir et al 2017), semiclassical (SC) method (Bates 1951;Gustafsson & Forrey 2019;Andreazza et al 2012;Andreazza & de Almeida 2014;Zámečníková et al 2020), quantum mechanical (QM) method (Golubev et al 2013;Antipov et al 2009;Barinovs & van Hemert 2006;Franz et al 2011;Gustafsson et al 2014;Nyman et al 2015;Andreazza et al 2016;Babb & McLaughlin 2017;Kathir et al 2017;Szabó & Gustafsson 2019;Zámečníková et al 2020;Babb et al 2019), Breit-Wigner theory (Breit & Wigner 1936;Bain & 1972; Zámečníková et al 2020;Szabo et al 2021), and optical potential method (Liu et al 2010;Mies 1969;Nyman et al 2015;Liu et al 2009), have been developed to compute the radiative association cross sections and rate coefficients. These methods have been extensively used to study small molecules in astrophysical environments, especially for diatomic molecules such as MgO (Bai et al 2021), N + 2 (Qin et al 2021), CS (Forrey et al 2018), AlO (Bai et al 2022), CN (Zhang et al 2022), CO (Meng et al 2022), CF + (Öström et al 2016), NaCl (Šimsová-Zámecníková et al 2022, BeH + and BeD + (Szabo et al 2021) and s...…”