Raman microprobe of laser-induced surface damage regions in TiO2 coatings

The anatase-to-rutile phase transition, which attends pulsed laser-induced damage of anatase TiO2 thin films, is studied by simultaneous microphotography and Raman microprobe. The damage is distributed across the damage area in regions of distinct morphology and spectra. In multilayer coatings, a mechanical surface-fracture zone surrounds a set of thin, layered flat rings of distinct but irregular boundaries. These rings surround a rough, pitted transparent central crater in the quartz substrate. Raman difference spectroscopy is used to reveal damage regions containing the rutile phase and regions devoid of TiO2