Infochemistry: Information Processing at the Nanoscale

Infochemistry, the science at the interface between chemistry and the information sciences, follows the potential use of molecular switches in advanced information processing and storage. Where traditional transistors are reaching their limits in miniaturization due to interconnectivity and material issues, molecular information processing could be the key to satisfying our ongoing need for increasing computational power. This book describes the processes, systems and devices employed in infochemistry, and characterizes chemical systems according to their role as potential elements in information technology. It includes: Theory of Information Limitations of traditional devices Low–Dimensional Metals and Semiconductors Carbon and Carbon–Rich Nanostructures Photocurrent switching and related phenomena Supramolecular assembly Molecular scale electronics, logic gates and computing systems Bioinspired and biomimetic logic devices Presenting a unique combination of chemistry and information technology, Infochemistry: Information Processing at the Nanoscale defines this new field of science, and its future possibilities for advanced information processing.

Preface xi Acknowledgements xiii 1 Introduction to the Theory of Information 1 1.1 Introduction 1 1.2 Definition and Properties of Information 2 1.3 Principles of Boolean Algebra 4 1.4 Digital Information Processing and Logic Gates 7 1.4.1 Simple Logic Gates 7 1.4.2 Concatenated Logic Circuits 10 1.4.3 Sequential Logic Circuits 11 1.5 Ternary and Higher Logic Calculi 14 1.6 Irreversible vs Reversible Logic 16 1.7 Quantum Logic 18 References 20 2 Physical and Technological Limits of Classical Electronics 23 2.1 Introduction 23 2.2 Fundamental Limitations of Information Processing 24 2.3 Technological Limits of Miniaturization 27 References 34 3 Changing the Paradigm: Towards Computation with Molecules 37 References 53 4 Low–Dimensional Metals and Semiconductors 63 4.1 Dimensionality and Morphology of Nanostructures 63 4.2 Electrical and Optical Properties of Nanoobjects and Nanostructures 70 4.2.1 Metals 70 4.2.2 Semiconductors 84 4.3 Molecular Scale Engineering of Semiconducting Surfaces 96 4.3.1 Semiconductor–Molecule Interactions 100 4.3.2 Electronic Coupling between Semiconducting Surfaces and Adsorbates 103 References 109 5 Carbon Nanostructures 119 5.1 Nanoforms of Carbon 119 5.2 Electronic Structure and Properties of Graphene 120 5.3 Carbon Nanotubes 129 5.4 Conjugated and Polyaromatic Systems 139 5.5 Nanocarbon and Organic Semiconductor Devices 149 References 156 6 Photoelectrochemical Photocurrent Switching and Related Phenomena 165 6.1 Photocurrent Generation and Switching in Neat Semiconductors 165 6.2 Photocurrent Switching in MIM Organic Devices 168 6.3 Photocurrent Switching in Semiconducting Composites 178 6.4 Photocurrent Switching in Surface–Modified Semiconductors 181 References 192 7 Self–Organization and Self–Assembly in Supramolecular Systems 199 7.1 Supramolecular Assembly: Towards Molecular Devices 199 7.2 Self–Assembled Semiconducting Structures 201 7.3 Self–Assembly at Solid Interfaces 210 7.4 Controlling Self–Assembly of Nanoparticles 212 7.5 Self–Assembly and Molecular Electronics 215 References 219 8 Molecular–Scale Electronics 225 8.1 Electron Transfer and Molecular Junctions 225 8.2 Nanoscale Electromagnetism 232 8.3 Molecular Rectifiers 238 References 246 9 Molecular Logic Gates 249 9.1 Introduction 249 9.2 Chemically Driven Logic Gates 249 9.2.1 OR Gates 252 9.2.2 AND Gates 255 9.2.3 XOR Gates 267 9.2.4 INH Gates 272 9.2.5 IMP Gates 281 9.2.6 Inverted Logic Gates (NOR, NAND, XNOR) 283 9.2.7 Behind Classical Boolean Scheme–Ternary Logic and Feynman Gate 289 9.3 All–Optical Logic Gates 298 9.4 Electrochemical Logic Systems 307 References 315 10 Molecular Computing Systems 323 10.1 Introduction 323 10.2 Reconfigurable and Superimposed Molecular Logic Devices 323 10.3 Concatenated Chemical Logic Systems 337 10.4 Molecular–Scale Digital Communication 353 10.4.1 Multiplexers and Demultiplexers 354 10.4.2 Encoders and Decoders 355 10.4.3 Molecular–Scale Signal Amplification 359 10.5 Molecular Arithmetics: Adders and Subtractors 363 10.5.1 Molecular–Scale Half–Adders 363 10.5.2 Molecular–Scale Half–Subtractors 372 10.5.3 Half–Adders/Half–Subtractors 381 10.5.4 Full Adders and Full Subtractors: Towards Molecular Processors 382 10.6 Molecular–Scale Security Systems 386 10.7 Noise and Error Propagation in Concatenated Systems 396 References 398 11 Bioinspired and Biomimetic Logic Devices 405 11.1 Information Processing in Natural Systems 405 11.2 Protein–Based Digital Systems 408 11.2.1 Enzymes as Information Processing Molecules 409 11.2.2 Enzymes as Information Carriers 428 11.3 Binary Logic Devices based on Nucleic Acids 430 11.4 Logic Devices Based on Whole Organisms 445 References 450 12 Concluding Remarks and Future Prospects 457 References 458 Index 461