Laser desorption-laser induced fluorescence (LD-LIF) is used to determine the surface coverage of chlorine during the steady-state etching of Si in an 18 mTorr inductively-coupled Cl@sub 2@-Ar plasma as a function of the rf power, substrate bias and Cl@sub 2@ fraction. Laser repetition rate studies, which indicate how the surface is re-chlorinated between laser pulses after each step of laser desorption of surface SiCl@sub x@, reveal that close to steady-state chlorination is achieved in the 10 ms time between 308-nm laser pulses (at 100 Hz) even with only 6% Cl@sub 2@ (94% Ar). This is not unexpected given our prior work in neat Cl@sub 2@ plasmas, for which there is near steady-state chlorination between such laser pulses at 1 mTorr pressure. A mechanism for the competitive etching processes of chlorination (mostly by Cl atoms in the bright mode) and surface sputtering (mostly by Ar and Cl positive ions) will be presented, by coupling these surface adlayer measurements with the etch rates and the optical emission actinometry determination of the densities of the major neutral and positive ions in the plasma.