Direct observation of transition between stick-slip and continuous sliding in atomic friction

The distortion and gradual recovery processes after a continuous tunable laser illuminating the graphite surface in air have been observed and analyzed in detail with a scanning tunneling microscope (STM). The slow response of the tip to the laser-induced mechanical elongation is responsible for the observed phenomena, which indicate that the transition between stick-slip and continuous sliding has occurred due to the atomically modulated friction between the STM tip and the graphite substrate.