The photoincrement of admittance (photoadmittance) of merocyaninehyphen;arachidic acid mixed Langmuirndash;Blodgett films sandwiched between aluminium electrodes has been measured for frequencies ohgr;/(2pgr;)1 Hz at room temperature using the monochromatized visible incident. The number of monolayers of the films was 3ndash;19. The photoadmittance is ascribed to photoelectrons from the dye chromophores. The lighthyphen;intensity dependence obeys a squarehyphen;root law for thicker films, approaching a linear law as the film thickness decreases. The frequency dependence is found to originate from the dispersive component proportional to ohgr;1minus;s, which predominates over the d.c. component for thicker films. The value ofsape;0.5 is evaluated with a critical length of about 30 nm as characterizing the crossover between the thinhyphen;film and the thickhyphen;film cases.
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