Total electron yields for perpendicular impact of C+ ions on W have been measured for projectile energies from 0.2 keV to 7 keV. The data are compared with the data of C+ bombardment of gold and graphite in order to demonstrate general trends in kinetic electron yields at low projectile velocities. The total electron yields in the studied combinations of projectiles and substrates show a similar exponential dependence Gamma proportional to (v/A) exp(-A/v), where A is a constant and v is the projectile velocity. (C) 2009 Elsevier B.V. All rights reserved.