OBSERVATION OF SUPERLUBRICITY BY SCANNING-TUNNELING-MICROSCOPY

Experimental evidence of superlubricity, the state of vanishing fricti on, is obtained by examining systems of sliding atomically clean surfa ces by using ultrahigh vacuum scanning tunneling microscopy. The exper imental results agree with theoretical predictions: Friction is not ob served in the superlubricity regime in measurements capable of resolvi ng a friction force of 3 x 10(-9) N, whereas friction of 8 x 10(-8) N, which is comparable to theoretical values, is observed in the frictio n regime.