The remarkable achievement by Fujishima and Honda (1972) in the photo-electrochemical water splitting results in the extensive use of TiO 2 nanomaterials for environmental purification and energy storage/conversion applications. Though there are many advantages for the TiO 2 compared to other semiconductor photocatalysts, its band gap of 3.2 eV restrains application to the UV-region of the electromagnetic spectrum ( λ  ≤ 387.5 nm). As a result, development of visible-light active titanium dioxide is one of the key challenges in the field of semiconductor photocatalysis. In this review, advances in the strategies for the visible light activation, origin of visible-light activity, and electronic structure of various visible-light active TiO 2 photocatalysts are discussed in detail. It has also been shown that if appropriate models are used, the theoretical insights can successfully be employed to develop novel catalysts to enhance the photocatalytic performance in the visible region. Recent developments in theory and experiments in visible-light induced water splitting, degradation of environmental pollutants, water and air purification and antibacterial applications are also reviewed. Various strategies to identify appropriate dopants for improved visible-light absorption and electron–hole separation to enhance the photocatalytic activity are discussed in detail, and a number of recommendations are also presented.

/pdf/visible-light-activation-of-tio2-photocatalysts-advances-in-37hmh9krsz.pdf

Visible-light activation of TiO2 photocatalysts: Advances in theory and experiments

Reflection is a natural phenomenon that occurs when light passes the interface between materials with different refractive index. In many applications, such as solar cells or photodetectors, reflection is an unwanted loss process. Many ways to reduce reflection from a substrate have been investigated so far, including dielectric interference coatings, surface texturing, adiabatic index matching and scattering from plasmonic nanoparticles. Here we present an entirely new concept that suppresses the reflection of light from a silicon surface over a broad spectral range. A two-dimensional periodic array of subwavelength silicon nanocylinders designed to possess strongly substrate-coupled Mie resonances yields almost zero total reflectance over the entire spectral range from the ultraviolet to the near-infrared. This new antireflection concept relies on the strong forward scattering that occurs when a scattering structure is placed in close proximity to a high-index substrate with a high optical density of states.

/pdf/broadband-omnidirectional-antireflection-coating-based-on-2c2zmz32og.pdf

Broadband omnidirectional antireflection coating based on subwavelength surface Mie resonators

This updated version of the popular handbook further explains all aspects of physical vapor deposition (PVD) process technology from the characterizing and preparing the substrate material, through deposition processing and film characterization, to post-deposition processing. The emphasis of the new edition remains on the aspects of the process flow that are critical to economical deposition of films that can meet the required performance specifications, with additional information to support the original material. The book covers subjects seldom treated in the literature: substrate characterization, adhesion, cleaning and the processing. The book also covers the widely discussed subjects of vacuum technology and the fundamentals of individual deposition processes. However, the author uniquely relates these topics to the practical issues that arise in PVD processing, such as contamination control and film growth effects, which are also rarely discussed in the literature. In bringing these subjects together in one book, the reader can understand the interrelationship between various aspects of the film deposition processing and the resulting film properties. The author draws upon his long experience with developing PVD processes and troubleshooting the processes in the manufacturing environment, to provide useful hints for not only avoiding problems, but also for solving problems when they arise. He uses actual experiences, called 'war stories', to emphasize certain points. Special formatting of the text allows a reader who is already knowledgeable in the subject to scan through a section and find discussions that are of particular interest. The author has tried to make the subject index as useful as possible so that the reader can rapidly go to sections of particular interest. Extensive references allow the reader to pursue subjects in greater detail if desired. The book is intended to be both an introduction for those who are new to the field and a valuable resource to those already in the field. The discussion of transferring technology between R&D and manufacturing provided in Appendix 1, will be of special interest to the manager or engineer responsible for moving a PVD product and process from R&D into production. Appendix 2 has an extensive listing of periodical publications and professional societies that relate to PVD processing. The extensive Glossary of Terms and Acronyms provided in Appendix 3 will be of particular use to students and to those not fully conversant with the terminology of PVD processing or with the English language. This title is fully revised and updated to include the latest developments in PVD process technology. It includes 'War stories' drawn from the author's extensive experience emphasize important points in development and manufacturing. Appendices include listings of periodicals and professional societies, terms and acronyms, and material on transferring technology between R&D and manufacturing.

Handbook of physical vapor deposition (PVD) processing

Within the field of spectral imaging, the vast majority of instruments used are scanning devices. Recently, several snapshot spectral imaging systems have become commercially available, providing new functionality for users and opening up the field to a wide array of new applications. A comprehensive survey of the available snapshot technologies is provided, and an attempt has been made to show how the new capabilities of snapshot approaches can be fully utilized.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-52/issue-9/090901/Review-of-snapshot-spectral-imaging-technologies/10.1117/1.OE.52.9.090901.pdf

Review of snapshot spectral imaging technologies

Quantum well excitons in semiconductor microcavities : unified treatment of weak and strong coupling regimes

(1986). Thin-film Optical Filters. Optica Acta: International Journal of Optics: Vol. 33, No. 11, pp. 1336-1336.

O.S. Heavens

Papers

Thin-film Optical Filters