Electronic bond rupture of Si-Dimers on Si(001)-(2x1) induced by pulsed laser excitation

A scanning tunneling microscopy study has revealed that 532 nm laser pulses of fluences well below melt and ablation thresholds induce electronic bond rupture of Si-dimers on the Si(001)-(2x1), resulting in the formation of single dimer-vacancies followed by progressive growth into vacancy clusters. The rate of bond rupture on the intrinsic (2x1) structure shows super-linearity with respect to excitation intensity, and saturates as the number of vacancies reaches a few percent, relative to total dimer sites. The mechanism of laser-induced bond rupture is discussed based on these results.