Marcia L. Manion Schilling

Polar orientation of dyes in robust multilayers by zirconium phosphate-phosphonate interlayers.

Polar orientation of molecules in solids leads to materials with potentially useful properties such as nonlinear optical and electrooptical activity, electrochromism, and pyroelectricity. A simple self-assembly procedure for preparing such materials is introduced that yields multiple polar dye monolayers on solid surfaces joined by zirconium phosphate-phosphonate interlayers. Second harmonic generation (SHG) shows that the multilayers have polar order that does not decrease with increasing numbers (up to a large number) of monolayers in the film. The inorganic interlayers, as determined by SHG, impart excellent orientational stability to the dye molecules, with the onset of orientational randomization above 150�C.

Photoinitiated electron-transfer reactions: the radical cations of bicyclo[1.1.0]butane derivatives

Irradiation du cyano-1 naphtalene ou du chloranile contenant du tricyclo [4.1.0.0 2,7 ] heptane, conduit a des intermediaires radicalaires cationiques derives du type bicyclo [1.1.0] butane. Forte polarisation de spin nucleaire. Spectre RMN protonique. Mecanismes

Radical cations of cyclopentadiene dimers—facets of an intriguing energy surface

Abstract The radical cations of various cyclopentadiene dimers can be generated by photoinduced electron transfer to strong electron acceptors. Nuclear spin polarization effects observed during these reactions provide insight into the radical cation structures. Three of the systems studied, endo-[4 + 2]-(1), anti-[2+2]-(2), and exo-(4+2]-dicyclopentadiene (5) give rise to unusual singly linked, delocalized radical cations, whereas the anti-[4 + 4]-dimer (3) and 1,3-bishomocubane (4) give rise to more conventional radical cations. The reactions of spiroheptadiene (9) and di(spiroheptadiene) (10) provide evidence for two different dimer radical cations, a doubly linked (D) and a singly linked (S) species. This finding supports a stepwise mechanism for the radical cation Diels-Alder reaction of 9.

Self-assembly: its use in at-the-surface imaging schemes for microstructure fabrication in resist films

Abstract The self-assembly of refractory films on organic resist surfaces is used to provide an etching mask during the plasma transfer of patterns through underlying organic resists. Multilayer self-assembly using ZrOCl2 and H4P2O7 reagents affords multilayer structures that are selectively bound to oxidized resist layers. Imaging is achieved using phenolic resin materials that are exposed to 193 nm radiation.

The electron transfer induced interconversion of cyclobutanes and diolefins

Abstract The photoreactions of quinones with diolefins ( 1 ) or cage compounds ( 2 ) give rise to nuclear spin polarization predominantly for the dilefins. These findings indicate that the cage cations ( 4 ) have shallow energy minima and suffer fast ring opening to the diolefin cations ( 3 ).

Selective Electroless Nickel Deposition on Patterned Phosphonate and Carboxylate Polymer Films

Electroless metallization processes have been used to develop photopatterned films of poly(diisopropyl vinylbenzylphosphonate-co-N-methylmaleimide) and deposit metallic nickel selectively in the exposed regions of the films. A 100 A thick film of nickel provides an effective etch mask to the underlying polymer in an oxygen plasma. Carboxylate polymers can also serve as substrates for electroless nickel deposition. These results suggest that phosphonate or carboxylate polymers could potentially serve as imaging layers for at-the-surface imaging approaches to 14 and 193 nm lithography.

Electrical and nonlinear optical properties of zirconium phosphonate multilayer assemblies

Multilayer assembly of organic chromophores with inorganic interlayers is a facile technique for the preparation of nonlinear optical materials with well-defined architectures. Recent reports of T. M. Mallouk (University of Texas-Austin) have indicated that zirconium organodiphosphonates form particularly stable surface multilayers that can be constructed straightforwardly one monolayer at a time. We have synthesized a series of chromophores with shapes and functional groups designed for layerwise deposition as zirconium phosphonates. These include electron donating thiophene oligomers, electron accepting quinodimethanes, and dipolar azo dyes. Cohesive, electrically insulating, thermally stable films of these compounds as layered phosphonates on various substrates were prepared with predictable thicknesses and, in some cases, polar order. Second harmonic intensity from the polar azo dye films was proportional to the thickness squared, consistent with theory. The dielectric and optical responses of a variety of other kinds of samples are discussed.

Solution-phase dielectric characterization of the 4-amino-4′-dicyanovinylazobenzene nonlinear-optical chromophore

The dielectric constants of solutions of 4-amino-4′-dicyanovinylazobenzene chromophore (DCV) at a wide range of concentrations in dioxane were measured. The chromophore dipole moment was determined to be 9.4 D in dioxane and in methyl trimethylacetate. Somewhat smaller values for the dipole moment were obtained when the chromophore was dissolved in chloroform or when it was covalently attached to a polymethacrylate backbone. No significant nonlinearity was observed in plots of dielectric constant versus concentration, even at concentrations approaching the solubility limit. Theoretical modeling indicates that such nonlinearity would have been observed if appreciable aggregation had occurred. It is predicted that dipole-dipole aggregation should not diminish the electric-field-induced alignment achievable in macroscopically homogeneous DCV-containing materials.

Dependence of nuclear spin polarization intensities on the plane of polarization of the exciting light. A caveat

The dependence of nuclear spin polarization effects on the plane of polarization of the exciting light has been evaluated for a wide range of radical (ion) pair reactions. The observed variations are of the same order of magnitude and in the same direction as an artifact expected on the basis of optical principles.

Photogenerated acid-catalyzed formation of phosphonic/phosphoric acids by deprotection of esters

A new class of photodefinable polymers based on phosphonic acid esters has been developed. Photogenerated acid catalysts convert the esters to phosphonic acids in the exposed regions of films during post-exposure bake. Those phosphonic acids, in addition to providing the base-solubility necessary for positive-tone development, are also uniquely capable of binding metal ions and cations from solution. Preliminary lithographic evaluations indicate that these polymers generally show high contrast (approximately 10), good sensitivity, low volume loss (< 15 percent) and the potential for submicron resolution. More importantly, the patterned deposition of refractory metal ions has also been demonstrated which could be useful for at-the- surface imaging and circuit fabrication applications.