Origin of negative differential resistance in molecular junctions of Rose Bengal

Negative differential resistance (NDR ) is tuned at the junctions of electronically different dimers and trimers of Rose Bengal. Isolated molecule did not show any NDR. But it was induced to show double and triple NDRs with large peak to valley ratio (1.8-3.1) at 300 K by varying number of neighbors and charging them by an electrical pulse. One could destroy or regenerate NDR by separating them or bringing together by a scanning tunneling microscope tip. NDR was also independent of polaronic nature. Bits 1 and 0 for cationic NDR (in dimer) and 0, 1, 2, and 3 for dianionic NDR (trimer) were written in an atomic scale junction. Importance of junction electronics and effective exposure is revealed. (c) 2007 American Institute of Physics.