LOW-TEMPERATURE SPECIFIC-HEAT OF PD NANOCRYSTALS

It is the first time that the quantum electronic effects in metal part icles is directly observed in low-temperature specific heat. In 32 Ang strom Pd nanocrystals at T <1K the linear coefficient of heat capacity gamma deviates from that of the bulk pd and reduces to a lower value. This is as expected to the case if measuring temperature T much less than the energy level spacing delta. At lower temperatures a quadratic temperature dependence of electronic specific heat is recognized, ind icating that the energy level distribution in Pd metal is an orthogona l function;one of the cases presented by Kubo theory.