2-Methyl-4-nitroaniline, nonlinear optical

Electronic and Nonlinear Optical Properties of 2-Methyl-4-Nitroaniline Clusters (M. Guillaume, B. Champagne, F. Castet L. Ducasse)... 

For these classes of conjugated molecular and polymer structures, the principal property is that their nonreson-ant, nonlinear optical responses are dominated by ultrafast, virtual excitations of the ir-electron states. This was directly demonstrated by MNA (2-methyl-4-nitroaniline) single crystal measurements of macroscopic second order susceptibilities at do (j 3) and optical frequencies (13-1 ) and combined second harmonic measurements and theo-... 

Chapter 2 Electronic and Nonlinear Optical Properties of 2-Methyl-4-Nitroaniline Clusters... 

The most common nonlinear optical molecules, with a donor—Ji-system—acceptor structure are, as a rule, neutral in the ground state and become charged in the excited state by electron transfer, in contrast with 4 -[Methyl(diphenyl)phosphonio]biphenyl-4-yl triphenylborate (PBB), which has a high dipole moment in the ground state and a lower one in the excited state. The hyperpolarizability P of PBB is comparable to that of p-nitroaniline and fortunately PBB shows transparency above 400 nm. 

In this experiment, three nitroaniline derivatives, i.e. p-nitro -aniline (p-NA), 2-hydroxy-i -nitroaniline(HNA) and N-methyl-i -nitroaniline (NMNA), were chosen as guest molecules because of their large optical nonlinearity. As a host molecule, dimethyl /-cyclodextrin (dimethyl f -CD) was used. It is well known that dimethyl /-CD forms an inclusion complex with many kinds of aromatic derivatives. 

Nason et al. [20] reported that polycrystalline thin films (1-10 /am) of the nonlinear material 2-methyl-4-nitroaniline were deposited on Ag, Cu, and Si by conventional and ionized cluster beam deposition. The use of ions was found to promote a highly oriented film, with only a single x-ray diffraction orientation (112) being observed at reduced temperatures (-50 C). The effect of the ions on the physical microstructure of the films was to densify the film and reduce the size of the microcrystals. The films had powder-like optical properties and displayed a strong second harmonic from an N YAG laser. 

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