9600138 Gorman It has now become an important but unanswered question as to whether molecules (or macromolecule at the 1-10 nm size scale) can be addressed and reliably store information. New techniques, particularly scanning tunnelling microscopy (STM), will certainly have use in these schemes. Nanolithography of metallic or semiconducting phases to create depressions or mounds on a surface can represent binary information, but atoms can diffuse, destroying this information. Ideally, information-bearing molecules could be moved into place and anchored to a surface. Subsequently, they could be switched and read without being influenced by their surroundings. In this project, both the molecular requirements and the process requirements for such a scheme will be addressed. In the former area, a new nanoscale unit will be synthesized. It is designed to be switchable, isolated from nearby units (so that the information it contains will not become scrambled), readable by an STM tip, and easily positioned on a surface (and thus addressable). It is argued that all of these criteria must be fulfilled before a molecule-based system can function as an information storage device. The molecule designed for this purpose will contain an electroactive core inside a dendrimeric polymer. This hybrid molecule will have an isolated, switchable information unit and simultaneously an easily tailored size, shape, and surface. Simultaneously, in the process area, methods for using the STM tip to perform chemical transformations on an organic surface (fashioned using self-assembled monolayers of organothiols on gold) will be explored. Rather than etching the surface, it is argued that site-specific reductive desorption of the organothiols into a solution over the surface will permit more predictable, reliable control over positioning of molecules on a surface. Both of these project segments will be directed towards demonstrations of those requirements for molecule-based information storage on a surface. %%% As computing elements become smaller and smaller, one must devise ways to encode information in smaller spaces. At least as far as strictly spatial encoding is concerned, the two most obvious schemes for nanoscale information storage are (a) continued miniaturization of known microscale elements to approach the nanoscale or (b) tailoring existing nanoscale objects e.g. molecules so that they can function as information bearing units (IBUs). In this proposal, macromolecular objects will be described that are tailored to serve as switchable, addressable, and organizable IBUs. It will be argued that only such a system will be suitable for use in nanoscale information encoding schemes. ***
