Counterion Effects on the Structure of Langmuir-Blodgett Films of a Benzothiazolium Dye |
| G.J. Ashwell, G. Jefferies, D.G. Hamilton and T. Handa Centre for Molecular Electronics, Cranfield University, Cranfield MK43 OAL, UK |
| Received: May 5, 1995; in final form: June 12, 1995 |
| Dedicated to Professor Krzyszof Pigoń on the occasion of his 70th birthday |
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| Langmuir-Blodgett films of salts of the two-legged cationic dye, E-N-hexadecyl-2-[2-(4-docosylaminophenyl)ethenyl]benzothiazolium, are Z-type. The molecular configuration within the Langmuir-Blodgett film is either "U-shaped" or "stretched" depending upon the nature of the anion, the thickness per layer being 35.1 Å for the octadecylsulphate and 54.1 Å for the iodide. For the Langmuir-Blodgett monolayers the principal components of the second order susceptibility (χzzz(2)) are 70 pm V-1 and 34 pm V-1 respectively at 532 nm. In the case of the octadecylsulphate salt it was possible to fabricate thick multilayer Langmuir-Blodgett films; the second harmonic intensity increased with the number of Z-type layers, albeit subquadratically, and this may be ascribed to a progressive variation in the chromophore tilt angle. |
| DOI: 10.12693/APhysPolA.88.483 PACS numbers: 73.20.Μf, 81.15.Lm |