Ground‐state CF and CF2radicals in CF4helicon plasmas of high density were detected by laser‐induced fluorescence (LIF). The LIF was used to measure the spatial and temporal variations of CFxconcentrations. The CF2concentration increases near 5–10 ms after the extinction of rf power, and the degree of this increase depends upon the discharge condition; plasma duration, plasma density, and CF4pressure. The result indicates that this behavior in the afterglow is closely related to the interactions of the rf‐on phase between radicals and a quartz surface with deposited fluorocarbon polymers. ©1995 American Institute of Physics.