Last year we launched Volume 1 of the Reviews in Fluorescence series. The volume was well-received by the fluorescence community, with many e-mails and letters providing valuable feedback, we subsequently thank you all for your continued support. After the volume was published we were most pleased to learn that the volume is to be citable and indexed, appearing on the ISI database. Subsequently, as well as the series having an impact number in due course, individual chapters will appear on the database and be both citable and keyword searchable. We feel that this will be a powerful resource to both authors and readers, further disseminating leading-edge fluorescence based material. Our intention with this new series is to both disseminate and archive the most recent developments in both past and emerging fluorescence based disciplines. While all chapters are invited, we welcome and indeed encourage the fluorescence community to suggest areas of interest that they feel need to be covered by the series. In this new volume. Reviews in Fluorescence 2005, Volume 2, we have invited reviews in areas such as: Multi-dimensional Time-correlated Single Photon Counting; Fluorescence Correlation Spectroscopy; RNA folding; Lanthanide Probes and Fluorescent Biosensors to name but just a few. We hope you find this volume a useful resource and we look forward to receiving any suggestions you may have. Finally we would like to thank the authors for their timely articles, Caroleann Aitken for the fi-ont cover design, Kadir Asian for typesetting and Mary Rosenfeld for administrative support.

This fourth volume in the Springer series summarizes the year’s progress in fluorescence, with authoritative analytical reviews specialized enough for professional researchers, yet also appealing to a wider audience of scientists in related fields.

This is the third volume in the Reviews in Fluorescence series. To date, two volumes have been both published and well received by the scientific community. Several book reviews have also favorably described the series as an "excellent compilation of material which is well balanced from authors in both the US and Europe". Of particular mention we note the recent book review in JACS by Gary Baker, Los Alamos. In this 3rd volume we continue the tradition of publishing leading edge and timely articles from authors around the world. We hope you find this volume as useful as past volumes, which promises to be just as diverse with regard to content. Finally, in closing, we would like to thank Dr Kadir Asian for the typesetting of the entire volume and our counterparts at Springer, New York, for its timely publication. Professor Chris D. Geddes Professor Joseph R. Lakowicz August 20*^ 2005.

This volume serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence spectroscopy. It summarizes the year’s progress in fluorescence and its applications as well as includes authoritative analytical reviews.

The Journal of Fluorescence’s fourth Who’s Who directory is to publish the names, contact details, specialty keywords, and a brief description of scientists employing fluorescence methodology and instrumentation in their working lives. In addition, the directory will provide company contact details with a brief list of fluorescence-related products. The directory will be edited by Chris D. Geddes and Joseph R. Lakowicz, editor and founding editor of the Journal of Fluorescence.

Over the last decade, fluorescence has become the dominant tool in biotechnology and medical imaging. These exciting advances have been underpinned by the advances in time-resolved techniques and instrumentation, probe design, chemical / biochemical sensing, coupled with our furthered knowledge in biology. Complementary volumes 9 and 10, Advanced Concepts of Fluorescence Sensing: Small Molecule Sensing and Advanced Concepts of Fluorescence Sensing: Macromolecular Sensing, aim to summarize the current state of the art in fluorescent sensing. For this reason, Drs. Geddes and Lakowicz have invited chapters, encompassing a broad range of fluorescence sensing techniques. Some chapters deal with small molecule sensors, such as for anions, cations, and CO2, while others summarize recent advances in protein-based and macromolecular sensors. The Editors have, however, not included DNA or RNA based sensing in this volume, as this were reviewed in Volume 7 and is to be the subject of a more detailed volume in the near future.

This book starts at an introductory level and leads reader to the most advanced topics in fluorescence imaging and super-resolution techniques that have enabled new developments such as nanobioimaging, multiphoton microscopy, nanometrology and nanosensors. The interdisciplinary subject of fluorescence microscopy and imaging requires complete knowledge of imaging optics and molecular physics. So, this book approaches the subject by introducing optical imaging concepts before going in more depth about advanced imaging systems and their applications. Additionally, molecular orbital theory is the important basis to present molecular physics and gain a complete understanding of light-matter interaction at the geometrical focus. The two disciplines have some overlap since light controls the molecular states of molecules and conversely, molecular states control the emitted light. These two mechanisms together determine essential imaging factors such as, molecular cross-section, Stoke shift, emission and absorption spectra, quantum yield, signal-to-noise ratio, Forster resonance energy transfer (FRET), fluorescence recovery after photobleaching (FRAP) and fluorescence lifetime. These factors form the basis of many fluorescence based devices. The book is organized into two parts. The first part deals with basics of imaging optics and its applications. The advanced part takes care of several imaging techniques and related instrumentation that are developed in the last decade pointing towards far-field diffraction unlimited imaging.