COLORATION EFFECT OF PULSED-LASER ON WO3

When laser pulses irradiate the surface of the sample WO3, an interest ing coloration effect is obtained. Only by one pulse of XeCl laser irr adiation (wavelength: 308 nm, pulse duration: 36 ns, output power: 100 mJ/pulse), a significant color change appears. X-ray photoelectron sp ectroscopy (XPS) shows that a partial reduction process of WO3 occurs and conduction band electrons appears. X-ray diffraction pattern indic ates that the lattice parameters of the colored samples are increased. A molten layer can be seen in scanning electron microscopy (SEM) imag e. It may be concluded that the coloration effect of pulsed laser unde rgoes a process different from that of electro- or photo- chromism, an d may be attributed to thermochromism and substoichiometric WO3 is for med. The coloration process is characterized by its high speed and sta bility.