Second Harmonlc Generatlon Studies of Methylene Blue Orlentatlon at Silica Surfaces

organization. When this film was reduced back to AgIITNPc (Figure 1 Ib) with hydrazine, the dichroic ratio declined almost to unity, indicating loss of order. A much thinner film (four layers) was used to repeat the liquid-phase experiment, with the same results being obtained. Thin-film reorganization upon redox sampling undoubtedly involves solvent transfer through the film.32*33 Thus, the loss of organization upon solvent-phase oxidation, but retention during gas-phase oxidation, may reflect the disruptive effect of such solvent transport in the former case. Summary and Conclusions. Highly ordered well-behaved Agl1TNPc(-2) Langmuir-Blodgett films can be deposited with stearic acid onto suitable substrates, with a deposition ratio of unity. Increasing stearic acid facilitates the transfer of a compact film but decreases the degree of organization of the Ag"TNPc(-2) component. The ESR spectra of the mixed Ag11TNPc(-2)/SteA films show that aggregation is still occurring, evidence that the stearic acid does not interleave between the Ag11TNPc(-2) molecules. Thus, dilute films are likely composed of domains of aggregated AgI1TNPc(-2) which are internally ordered, separated