Absolute luminescence efficiency of ion-bombarded solid argon

We have directly measured the absolute efficiency of the 9.8-eV M -band luminescence from the decay of Ar2* excimers in solid Ar bombarded by 1.5-MeV He 1 and 10–50-keV H ions. About 54% of the electronic energy deposited by the projectiles is converted to 9.8-eV luminescence energy, or about 5.5 photons per 100-eV deposited. The efficiency is also found to be independent of ion and ion energy for those tested over a range of stopping cross sections from 6.5 to 400 eV/(10 atoms/cm). This work clearly establishes the M band as the major relaxation pathway for electronically deposited energy in solid Ar, a pathway that is an important source of radiation damage and sputtering and which can be affected by electron emission. @S0163-1829~97!00535-3#