Continuum light emission from sputtered species of graphite during ion beam irradiation

Light emission during sputtering of graphite targets with 1-10 keV Ne+, Kr and Xe+ beams has been investigated in the 180-600 nm wavelength range. Be side the characteristic lines of sputtered C-1 and C-1(+), a continuum supe rimposed with a number of broad structures was observed in the 250-520 nm r ange, and having a maximum at 386 nm. Mass analysis of the sputtered flux c onfirmed the presence of negative carbon clusters C-m(-) (m less than or eq ual to 4), C-2(-) being the dominant one. Ion beam parameters i.e. ion mass , energy, current density and ion dose were varied to identify the origin o f the continuum emission. On the basis of the experimental results, it is s uggested that the continuum is predominantly due to the overlapping of vari ous band systems of sputtered C-2 with a small contribution from the heavie r sputtered carbon clusters C-m (m > 2).