The mechanism of the unidirectional rotational motion of a chiral molecular motor driven by linearly polarized laser pulses was theoretically studied.A simple aldehyde molecule was adopted as a chiral molecular motor,in which a formyl group (-CHO)was the rotating part of the motor.as a chiral molecular motor,in which a formyl group (-CHO)was the rotating part of the motor.Temporal oriented motors were taken as a measure of the unidirectional motion.The contour plots of the averaged instantaneous angular momentum were obtained by usign a quantum master equation approach that took into account relaxatin effects and a classical trajectory approach.Two regimes are found in the contour plots.One is an intense laser field regime in which the laser-motor interaction energy exceeds the asymmetric potential barrier.In this regime,the motors are unidirectionally drive in the intuitive direction,i.e.,the gentle slope of the potential.The other regime is a subthreshold laser intensity regime in which unintuitive rotational motions also occur.This unintuive rotation is found to be a quantum effect,as indicated by contour plots calculated by taking into account temperature effects.
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