Femtosecond Near-Infrared Laser Desorption of Multilayer Benzene on Pt{111}: A Molecular Newton's Cradle?

Velocity distributions resulting from the intense, near-IR laser desorption of multilayers of benzene adsorbed on Pt{111} are reported as a function of laser intensity, which was varied by changing fluence and pulse width. The velocity distributions as a function of intensity show characteristics of both thermally and electronically induced desorption. Changing the pulse width from the subpicosecond to the subnanosecond regime only results in a small quantitative change in the velocity distributions, suggesting a similar desorption mechanism for laser pulse duration spanning 3 orders of magnitude. Possible mechanisms are discussed and a new mechanism is proposed in which the process is initiated by a thermally assisted DIET excitation in the chemisorbed layer, and followed by energy transfer from the Pt−benzene interface to the outermost benzene layers via a molecular Newton's cradle mechanism.