Molecular detection based on conductance quantization of nanowires

We have studied molecular adsorption onto stable metallic nanowires fabrica ted with an electrochemical method. Upon the adsorption, the quantized cond uctance decreases, typically, to a fractional value, which may be attribute d to the scattering of the conduction electrons by the adsorbates. The furt her conductance change occurs when the nanowire is exposed to another molec ule that has stronger adsorption strength. Because the quantized conductanc e is determined by a few atoms at the narrowest portion of each nanowire, a dsorption of a molecule onto the portion is enough to change the conductanc e, which may be used for chemical sensors. (C) 2000 American Institute of P hysics. [S0003-6951(00)01610-7].