Laser-induced desorption and etching processes on chlorinated Cu and solid CuCl surfaces

Time-resolved mass spectrometry is used to study the desorbed species due to laser-induced etching of a solid CuCl and a chlorinated Cu surface. The observed desorption threshold, mass distribution and kinetic energies of the desorbed atoms and molecules at 355 and 532 nm radiation show that the laser-induced etching process is not simply thermal evaporation. It is suggested that competing nonthermal mechanisms due to electronic excitations may be very important in laser-induced desorption and etching. These processes are different for a solid CuCl and a chlorinated Cu surface. For laser-induced etching of Cu surfaces, chlorination of Cu is essential; however, formation of stoichiometric CuCl is not necessary. Excess Cu in the surface layer is responsible for the observed different etching behavior of a chlorinated Cu and a solid CuCl surface. The effect of laser radiation on these surfaces and possible etching mechanisms are discussed based on the experimental observations.