Vibrationally resolved electron impact electronic excitation of BeH

Beryllium is being adopted for plasma facing walls in fusion reactors. This has led to the observation of emissions from the A (2)pi state of beryllium hydride. Use of these emissions to monitor Be erosion requires electron impact excitation rates. Cross sections for electron impact vibrational excitation within the X (2)sigma(+) state and vibrationally resolved electronic excitation to the A (2)pi state are reported for BeH, BeD and BeT. Electron collisions are studied at a range of internuclear separations using the UK molecular R-matrix (UKRmol+) codes. Electronic excitation is studied both within the Franck-Condon approximation and by explicit averaging of the T-matrix elements. It is found that (a) inclusion of the effect of higher partial waves using the Born approximation leads to significant increases in the cross sections and (b) the Franck-Condon approximation underestimates the importance of collisions for which the vibrational state changes during electronic excitation.