Radiative association

Radiative association is one of several processes that contribute to the production of molecules in certain space environments, such as the interstellar medium and proto-planetary disks. Radiative association is particularly important in regions with a small fraction of "larger" particles (such as dust grains and larger), where chemical reactions due to three-body collisions are extremely rare. Experimental lab studies of radiative association are extremely complicated, necessitating the need for theoretical computer calculations.

In our group we focus a lot on quantum effects in the process (e.g. collisional resonances and non-adiabatic couplings). To describe the dynamics (atomic motion) we use time-independent quantum mechanics in combination with classical trajectory calculations. Radiative association for a number of neutral molecules has been investigated (CN, CO, SiN, SiP, HF, HD, and NaK). We are currently (2015) working with ion systems and polyatomic systems.

Publications:

• A surface-hopping method for semiclassical calculations of cross sectionsfor radiative association with electronic transitions
• Radiative association rate constant for the formation of CO: the importance of the first excited 1Sigma+ state