Water at the graphene–substrate interface: interaction with short laser pulses

We have investigated the role of adsorption water in the local transformation of multilayer graphene deposited on an oxidised silicon substrate, which was exposed to nanosecond low-intensity focused laser radiation with a wavelength of 532 nm in the air. Experimental data obtained for a laser energy density E=0.04 J cm^-2 suggest that the formation of micropits (craters) is a consequence of the multipulse removal of the layer of a water adsorbate, which is intercalated between graphene and the substrate, from the zone of laser irradiation of the graphene sheet. The energy threshold of graphene damage in the regions devoid of water was found to be higher in comparison with the initial one (0.058 against 0.048 J cm^-2). According to computer simulations of the heating dynamics of the sample and the heat distribution in the substrate–adsorbate–graphene multilayer system, at energy densities corresponding to the experimental ones the water adsorbate layer heats to a temperature sufficiently high to form an increased-pressure vapour cavity under the graphene film.