Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2

http://pubs.acs.org/doi/pdf/10.1021/cr1002326

Solar Water Splitting Cells

/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Signaling Recognition Events with Fluorescent Sensors and Switches.

TiO2 photocatalysis and related surface phenomena

https://easyspin.org/pubs/easyspin_jmr06.pdf

EasySpin, a comprehensive software package for spectral simulation and analysis in EPR.

Basic Principles of Electron Paramagnetic Resonance Magnetic Interactions Between Particles Isotropic Hyperfine Effects in EPR Spectra g-Anisotropy in Solids Hyperfine Anisotropy in Solids Systems with More than One Unpaired Electron Paramagnetic Species in Gas Phase Transition-Group Ions The Interpretation of EPR Parameters Relaxation Times, Linewidths and Kinetic Phenomena Time-Dependent Excitation of Spins Double-Resonance Techniques Other Topics.

Electron paramagnetic resonance : elementary theory and practical applications

Ultraviolet (UV) disinfection is now an accepted technology for inactivation of a variety of waterborne pathogens in wastewater and drinking water. However, the techniques used in much of the previous research aimed at providing information on UV effectiveness have not yet been standardized. Thus in many peer reviewed published literature, it is not clear how the UV irradiations were carried out, nor how the average \Ifluence\N (or UV dose) given to the microorganisms has been determined. A detailed protocol for the determination of the fluence (UV dose) in a bench scale UV apparatus containing UV lamps emitting either monochromatic or broadband UV light was developed. This protocol includes specifications for the construction of a bench scale UV testing apparatus, methods for determination of the average irradiance in the water, details on UV radiometry, and considerations for microbiological testing. Use of this protocol will aid in standardization of bench scale UV testing and provide increased confidence in data generated during such testing.

Standardization of Methods for Fluence (UV Dose) Determination in Bench-Scale UV Experiments

1 Basic Principles of Electron Spin Resonance.- 1-1 Introduction.- 1-2 Energy of Magnetic Dipoles in a Magnetic Field.- 1-3 Quantization of Angular Momentum.- 1-4 Relation between Magnetic Moments and Angular Momenta.- 1-5 Interaction of Magnetic Dipoles with Electromagnetic Radiation.- 1-6 Characteristics of the g Factor.- Problems.- 2 Basic Instrumentation of Electron Spin Resonance.- 2-1 A Simple ESR Spectrometer.- 2-2 Choice of Experimental Conditions.- 2-3 Typical Spectrometer Arrangement.- 2-3a The Cavity System.- 2-3b The Source.- 2-3c The Magnet System.- 2-3d The Modulation and Detection Systems.- 2-4 Line Shapes and Intensities.- References.- Problems.- 3 Nuclear Hyperfine Interaction.- 3-1 Introduction.- 3-2 Origins of the Hyperfine Interaction.- 3-3 Energy Levels of a System with One Unpaired Electron and One Nucleus with I = 1/2.- 3-4 The Energy Levels of a System with S = 1/2 and I=1.- 3-5 Summary.- Problems.- 4 Analysis of Electron Spin Resonance Spectra of Systems in the Liquid Phase.- 4-1 Introduction.- 4-2 Energy Levels of Radicals Containing a Single Set of Equivalent Protons.- 4-3 ESR Spectra of Radicals Containing a Single Set of Equivalent Protons.- 4-4 ESR Spectra of Radicals Containing Multiple Sets of Equivalent Protons.- 4-5 Hyperfine Splittings from Other Nuclei with I = 1/2.- 4-6 Hyperfine Splittings from Nuclei with I > 1/2.- 4-7 Useful Rules for the Interpretation of Spectra.- 4-8 Other Problems Encountered in the ESR Spectra of Free Radicals.- 4-9 Second-order Splittings.- Problems.- 5 Interpretation of Hyperfine Splittings in ?-type Organic Radicals.- 5-1 Introduction.- 5-2 Molecular Orbital Energy Calculations.- 5-3 Unpaired Electron Distributions.- 5-4 The Benzene Anion and Its Derivatives.- 5-5 The Anions and Cations of the Polyacenes.- 5-6 Other Organic Radicals.- 5-7 Summary.- References-HMO Method.- Problems.- 6 Mechanism of Hyperfine Splittings in Conjugated Systems.- 6-1 Origin of Proton Hyperfine Splittings.- 6-2 Sign of the Hyperfine Splitting Constant.- 6-3 Extension of the Molecular Orbital Theory to Include Electron Correlation.- 6-4 Alkyl Radicals-A Study of Q Values.- 6-5 The Effect of Excess Charge on the Parameter Q.- 6-6 Methyl-proton Hyperfine Splittings-Hyperconjugation.- 6-7 Hyperfine Splitting by Nuclei Other than Protons.- Problems.- 7 Anisotropic Interactions in Oriented Systems with S = 1/2.- 7-1 Introduction.- 7-2 A Simple Example of Anisotropy of g.- 7-3 Systems with Orthorhombic or Lower Symmetry.- 7-4 Experimental Determination of the g Tensor in Oriented Solids.- 7-5 Anisotropy of the Hyperfine Coupling.- 7-6 Origin of the Anisotropic Hyperfine Interaction.- 7-7 Determination of the Elements of the Hyperfine Tensor.- 7-8 Corrections to Hyperfine Tensor Elements.- 7-9 Line Shapes in Nonoriented Systems.- 7-9a Line Shapes for Systems with Axial Symmetry.- 7-9b Hyperfine Line Shapes for an Isotropic g Factor, S = 1/2 and One Nucleus with I = 1/2.- Problems.- 8 Interpretation of the ESR Spectra of Systems in the Solid State.- 8-1 Generation of Free Radicals in Solids.- 8-2 ?-type Organic Radicals.- 8-2a Identification.- 8-2b Aliphatic Radicals.- 8-2c Radicals from Unsaturated Organic Compounds.- 8-3 ?-type Organic Radicals.- 8-4 Inorganic Radicals.- 8-4a Identification of Radical Species.- 8-4b Structural Information.- 8-5 Point Defects in Solids.- 8-5a Generation of Point Defects.- 8-5b Substitutional or Interstitial Impurities.- 8-5c Trapped-electron Centers.- 8-5d Trapped-hole Centers.- References.- Problems.- 9 Time-dependent Phenomena.- 9-1 Introduction.- 9-2 Spin-lattice Relaxation Time.- 9-3 Other Sources of Line Broadening.- 9-3a Inhomogeneous Broadening.- 9-3b Homogeneous Broadening.- 9-4 Mechanisms Contributing to Line Broadening.- 9-4a Electron Spin-Electron Spin Dipolar Interactions.- 9-4b Electron Spin-Nuclear Spin Interactions.- 9-5 Chemical Line-broadening Mechanisms.- 9-5a General Model.- 9-5b Electron-spin Exchange.- 9-5c Electron Transfer.- 9-5d Proton Exchange.- 9-6 Variation of Linewidths within an ESR Spectrum.- 9-6a Time-dependent Hyperfine Splitting for a Single Nucleus.- 9-6b Time-dependent Hyperfine Splittings for Systems with Several Nuclei.- 9-7 Spectral Effects of Slow Molecular Tumbling Rates.- 9-8 Spectral Effects of Rapid Molecular Tumbling Rates-Spin-rotational Interaction.- 9-9 Summary.- Problems.- 10 Energy-level Splitting in Zero Magnetic Field The Triplet State.- 10-1 Introduction.- 10-2 The Spin Hamiltonian for S = 1.- 10-3 State Energies for a System with S = 1.- 10-4 The Spin Eigenfunctions for a System with S=1.- 10-5 Electron Spin Resonance of Triplet-state Molecules.- 10-6 Line Shapes for Randomly Oriented Systems in the Triplet State.- 10-7 The "?MS = 2" Transitions.- 10-8 Triplet Ground States.- 10-9 Carbenes and Nitrenes.- 10-10 Thermally Accessible Triplet States.- 10-11 Biradicals Exchange Interaction.- 10-12 Systems with S > 1.- Problems.- 11 Transition-metal Ions. I..- 11-1 States of Gaseous Transition-metal Ions.- 11-2 Removal of Orbital Degeneracy in Crystalline Electric Fields.- 11-3 The Crystal Field Potential.- 11-4 The Crystal Field Operators.- 11-5 Crystal Field Splittings of States for P-, D- and F-state Ions.- 11-6 Spin-orbit Coupling and the Spin Hamiltonian.- 11-7 D- and F-state Ions with Orbitally Nondegenerate Ground States.- 11-7a D-state Ions 3d1(ttdl + ttgl) in 3d1(cubal + ttgl) 3d7(1s)(oct + ttgl) 3d9(oct + ttgl).- 11-7b F-state Ions 3d8(oct) 3d2(ttdl) 3d8(oct + ttgl) 3d2(ttdl + ttgl) 3d3(oct) 3d7(hs)(ttdl) 3d3(oct + ttgl).- 11-8 S-state Ions 3d5(hs)(oct) 3d5(hs)(oct + ttgl).- Problems.- 12 Transition-metal Ions. II. Electron Resonance in the Gas Phase.- 12-1 Ions in Orbitally Degenerate Ground States.- 12-1a D-state Ions 3d1(oct) 3d1(oct + ttgl), ? > > ? > > ? 3d1(oct + ttgl), ? > > ? ? ? 3d1(oct + trgl) 3d5(1s)(oct + ttgl) 3d9(ttdl + ttgl) 3d6(hs)(oct).- 12-1b F-state Ions 3d2(oct) 3d2(oct + trgl) 3d7(hs)(oct).- 12-1c Jahn-Teller Splitting 3d9(oct) 3d7(1s)(oct).- 12-2 Elements of the 4d and 5d Groups (Palladium and Platinum Groups).- 12-3 The Rare-earth Ions.- 12-4 The Actinide Ions.- 12-5 Deficiencies of the Point-charge Crystal Field Model Ligand-Field Theory.- 12-6 Electron Resonance of Gaseous Free Radicals.- 12-7 The Practical Interpretation of ESR Spectra of Ions in the Solid State.- Problems.- 13. Double-resonance Techniques.- 13-1 An ENDOR Experiment.- 13-2 Energy Levels and ENDOR Transitions.- 13-3 Relaxation Processes in Steady-state ENDOR.- 13-4 An ENDOR Example: The F Center in the Alkali Halides.- 13-5 ENDOR in Liquid Solutions.- 13-6 ENDOR in Powders and Nonoriented Solids.- 13-7 Electron-electron Double Resonance.- Problems.- 14. Biological Applications of Electron Spin Resonance.- 14-1 Introduction.- 14-2 Substrate Free Radicals.- 14-3 Flavins and Metal-free Flavoproteins.- 14-4 Photosynthesis.- 14-5 Heme Proteins.- 14-6 Iron-sulfur Proteins.- 14-7 Spin Labels.- Appendix A. Mathematical Operations.- A-1 Complex Numbers.- A-2 Operator Algebra.- A-2a Properties of Operators.- A-2b Eigenvalues and Eigenfunctions.- A-3 Determinants.- A-4 Vectors: Scalar, Vector, and Outer Products.- A-5 Matrices.- A-5a Addition and Subtraction of Matrices.- A-5b Multiplication of Matrices.- A-5c Special Matrices and Matrix Properties.- A-5d Dirac Notation for Wave Functions and Matrix Elements.- A-5e Diagonalization of Matrices.- A-6 Tensors.- A-7 Perturbation Theory.- A-8 Euler Angles.- Problems.- Appendix B. Quantum Mechanics of Angular Momentum.- B-1 Introduction.- B-2 Angular-momentum Operators.- B-3 The Commutation Relations for the Angular-momentum Operators.- B-6 Angular-momentum Matrices.- B-7 Addition of Angular Momenta.- B-8 Summary.- Problems.- C-1 The Hamiltonian for the Hydrogen Atom.- C-2 The Spin Eigenfunctions and the Energy Matrix for the Hydrogen Atom.- C-3 Exact Solution of the Determinant of the Energy Matrix (Secular Determinant).- C-4 Selection Rules for High-field Magnetic-dipole Transitions in the Hydrogen Atom.- C-5 The Transition Frequencies in Constant Magnetic Field with a Varying Microwave Frequency.- C-6 The Resonant Magnetic Fields at Constant Microwave Frequency.- C-7 Calculation of the Energy Levels of the Hydrogen Atom by Perturbation Theory.- C-8 Wave Functions and Allowed Transitions for the Hydrogen Atom at Low Magnetic Fields.- Problems.- Appendix D. Experimental Methods Spectrometer Performance.- D-1 Sensitivity.- D-2 Factors Affecting Sensitivity and Resolution.- D-2a Modulation Amplitude.- D-2b Modulation Frequency.- D-2c Microwave Power Level.- D-2d The Concentration of Paramagnetic Centers.- D-2e Temperature.- D-2g Microwave Frequency.- D-2h Signal Averaging.- D-3 Absolute Intensity Measurements.- Problems.- Table of Symbols.- Name Index.

Electron Spin Resonance: Elementary Theory and Practical Applications

It has long been known that the photolysis of nitrite and nitrate solutions results in the formation of OH radicals. The mechanism of NO3− photolysis has been the subject of considerable controversy in the literature, however. This review summarizes the experimental work on NO2− and NO3− photolysis in the context of recent advances in the understanding of the chemistry of the peroxynitrite anion (ONOO−) in biological experiments. ONOO− has been found to play a far more significant role in the overall reaction mechanism of NO3− photolysis than had previously been suspected. Research on NO2− and NO3− photolysis, as a pathway to the destruction of organic contaminants in natural waters, is summarized. The possible impact of NO2− and NO3− on Advanced Oxidation Technologies (AOTs), in which OH radicals are used to initiate the destruction of hazardous organic pollutants in drinking water and industrial waste streams, is explored.

Photochemistry of nitrite and nitrate in aqueous solution: a review

Advanced oxidation technologies (AOTs), which involve the in situ generation of highly potent chemical oxidants, such as the hydroxyl radical (•OH), have emerged as an important class of technologies for accelerating the oxidation (and hence removal) of a wide range of organic contaminants in polluted water and air. In this report, standard figures-of-merit are proposed for the comparison and evaluation of these waste treatment technologies. These figures-of-merit are based on electric-energy consumption (for electric-energy-driven systems) or collector area (for solar-energy-driven systems). They fit within two phenomenological kinetic order regimes: 1) for high contaminant concentrations (electric energy per mass, EEM, or collector area per mass, ACM) and 2) for low concentrations (electric energy per order of magnitude, EEO, or collector area per order of magnitude, ACO). Furthermore, a simple understanding of the overall kinetic behavior of organic contaminant removal in a waste stream (i.e., whether zeroor first-order) is shown to be necessary for the description of meaningful electricor solar-energy efficiencies. These standard figures-of-merit provide a direct link to the electricor solar-energy efficiency (lower values mean higher efficiency) of an advanced oxidation technology, independent of the nature of the system, and therefore allow for direct comparison of widely disparate AOTs. These figures-of-merit are also shown to be inversely proportional to fundamental efficiency factors, such as the lamp efficiency (for electrical systems), the fraction of the emitted light that is absorbed in the aqueous solution, and the quantum yield of generation of active radicals.

Figures-of-merit for the technical development and application of advanced oxidation technologies for both electric- and solar-driven systems (IUPAC Technical Report)

James R. Bolton

Papers

Electron paramagnetic resonance : elementary theory and practical applications

Standardization of Methods for Fluence (UV Dose) Determination in Bench-Scale UV Experiments

Electron Spin Resonance: Elementary Theory and Practical Applications

Photochemistry of nitrite and nitrate in aqueous solution: a review

Figures-of-merit for the technical development and application of advanced oxidation technologies for both electric- and solar-driven systems (IUPAC Technical Report)