抄録
Conductance fluctuations were observed in CuSO4 aqueous ionic solutions over ion concentrations from 5×10−4 to 10−2 mol/l. It is found that the spectral density is approximately 1⁄f for ion drift velocities smaller than a critical value which is of order of 10−3 m/s; above this value it approaches a Lorentzian form. The α-value of the 1⁄f fluctuation is approximately proportional to the ion concentration when it is larger than 10−3 mol/l; below this critical value the α-value seems to take a constant value 2.5×10−2. The existence of the critical ion concentration suggests that, if the 1⁄f conductance fluctuations are caused by mobility fluctuations, the 1⁄f conductance fluctuation has a coherence length, which is estimated to be 10 nm.
