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Title: The Pockels' effect in Langmuir-Blodgett films
Author: Kalita, N.
ISNI:       0000 0001 3594 0949
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 1991
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Simple, compact and inexpensive automated apparatus for recording surface plasmon resonance and the Pockels (or linear electro-optic) effect in Langmuir-Blodgett films has been used to estimate the thickness, permittivity and second order non linear susceptibility X(^(2))(_xxx)(-w;w,0) of several novel Langmuir-Blodgett film-forming materials. The results agree with estimates of nonlinear susceptibility obtained by second-harmonic generation. The materials synthesised at Durham were all functionalised diaryl alkynes of the general formula CH(_3)(CH(_2))(_n)(Py(^+))C=C(Ph-R), wherein n =17 or 21 and R=H or OCH(_3). Of these, that with n =21 and R=OCH(_3) showed particularly promising Langmuir-Blodgett film-forming properties; its nonlinear susceptibility per mono layer, however, was approximately one hundredth that of a hemicyanine monolayer. The nonlinear susceptibility per monolayer, as measured by the Pockels effect and second harmonic generation, was inversely proportional to the square root of the film thickness. This indicated rapid deterioration of in-plane order with increasing film thickness. Several novel polymeric materials synthesised at Hull and examined at Durham consisted of a siloxane spine of approximately 16 Si atoms, with randomly substituted bipolar chromophoric sidegroups. All were highly stable in floating film form. Of them, one known as AMCR23 showed promising optical nonlinearity when deposited on silver: a nonlinear susceptibility of-15+9.6i pm V(^-1) was recorded for a monolayer (cf. 94.5+49.9i pm V(^-1) for a hemicyanine monolayer).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Solid-state physics