A study is undertaken of the loss kinetics of H and Cl atoms in an inductively coupled plasma (ICP) reactor used for the etching of III-V semiconductor materials. A time-resolved optical emission spectroscopy technique, also referred to as pulsed induced fluorescence (PIF), has been combined with time-resolved microwave hairpin probe measurements of the electron density in a pulsed Cl-2/H-2-based discharge for this purpose. The surface loss rate of H, k(w)(H), was measured in H-2 plasma and was found to lie in the 125-500 s(-1) range (gamma(H) surface recombination coefficient of (0.006-0.023), depending on the reactor walls conditioning. The PIF technique was then evaluated for the derivation of k(w)(Cl), and gamma(Cl) in Cl-2-based plasmas. In contrast to H-2 plasma, significant variations in the electron density may occur over the millisecond time scale corresponding to Cl-2 dissociation at the rising edge of the plasma pulse. By comparing the temporal evolution of the electron density and the Ar-line intensity curves with 10% of Ar added in the discharge, the authors show that a time-resolved actinometry procedure using Ar as an actinometer is valid at low to moderate ICP powers to estimate the Cl loss rate. They measured a Cl loss rate of similar to 125-200 s(-1) (0.03 <= gamma(Cl) <= 0.06) at 150 W ICP power for a reactor state close to etching conditions. The Cl surface loss rate was also estimated for high ICP power (800 W) following the same procedure, giving a value of similar to 130-150 s(-1) (gamma(Cl) similar to 0.04), which is close to that measured at 150 W ICP power. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3330766]