Visible light footprinting - is it possible?

We have colleagues who user UV lasers to excite hydrogen peroxide to create hydroxyl radicals (this is the method called FPOP) but we were wondering if it might be possible to use visible light to do footprinting. We turned to an expert in the NanoFab facility at the Molecular Foundry, Adam Schwartzberg, who has a femtosecond high-powered optical laser. The idea is that with such short time pulses, non-linear photon absorption gives enough energy to break water. Preliminary results were promising, at least with a dye sample. Next step: trying it out with proteins!