MODES OF VIBRATIONS IN STEP TRAINS - RHYTHMICAL BUNCHING

Although possible mechanisms have been suggested theoretically for exciting modes of vibrations in step trains, neither explicit treatment was made, nor experimental observations reported to show how a periodicity is introduced into step patterns. Out of numerous observations on crystal surfaces, several examples which show an almost strict periodicity in step trains imposed by modes of vibrations are reported in this paper. Starting from the demonstration of the zeroth mode of vibration, examples are presented to show periodicity imposed by: (a) the centre of the spiral system; (b) the decomposition of double steps; and (c) the difference in advancing rates between double and single steps. © 1979.