Controlling the photodesorption of adspecies from surfaces

The enhancement of photodesorption cross sections by shaped laser pulses is demonstrated here using quantum dynamical methods. Two model systems are chosen. The first one is H:Si(1 0 0)-(2 × 1), where IR laser-induced desorption of H atoms by “ladder climbing” in the ground electronic state is demonstrated. The second system is H:Ru(0 0 0 1)-(1 × 1), where a hybrid IR + UV/vis scheme is considered to increase the desorption yield of H2 after hot electron-mediated electronic excitation. It is found that shaped IR pulses are useful tools to control photodesorption, even if the coupling of the adsorbate to the surface, either to phonons or electron–hole pairs, is strong.