ANOMALOUS PHOTOCONDUCTIVITY OF FERROCENE

Photoconductivity behaviour of ferrocene, a very useful metallo-organi c sandwich compound, has been investigated at different constant tempe ratures using powdery material in a sandwich type of cell configuratio n and with the exposure of a polychromatic light source (mercury lamp of 125 W). Measurements with a constant d.c, bias voltage (27 V) acros s the sample cell and a fixed intensity of the exciting light source h ave shown a drastic change in the photocurrent versus time profile wit h the increase in temperature. Anomalous changes have been observed in the plot of the photocurrent versus reciprocal of temperature. Such c hanges are completely absent in the corresponding dark current behavio ur. The photoinduced changes have been observed to be almost reversibl e in the entire temperature range. In a particular temperature range t he reversibility of photocurrent is accompanied by fluctuations in equ ilibrium current obtained after switching off the light source. The ob served anomalous changes in photocurrent have been explained by photoi nduced phase transition in ferrocene. The possible origin and implicat ions of this photoinduced phase transition are discussed.