Showing papers by "Paul Scherrer Institute published in 2005"
TL;DR: In this article, the mechanisms of lithium-ion battery ageing are reviewed and evaluated, and the most promising candidate as the power source for (hybrid) electric vehicles and stationary energy storage.
3,115 citations
TL;DR: Using a high-efficiency grating interferometer for hard X rays (10-30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from a single set of measurements.
Abstract: Using a high-efficiency grating interferometer for hard X rays (10-30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from a single set of measurements. Tomographic reconstruction yields quantitative three-dimensional maps of the X-ray refractive index, with a spatial resolution down to a few microns. The method is mechanically robust, requires little spatial coherence and monochromaticity, and can be scaled up to large fields of view, with a detector of correspondingly moderate spatial resolution. These are important prerequisites for use with laboratory X-ray sources.
1,264 citations
TL;DR: In this paper, the authors review the underlying science and describes the technological advances in the field of solar thermochemical production of hydrogen that uses concentrated solar radiation as the energy source of high-temperature process heat.
1,170 citations
TL;DR: In this paper, the results of the Sun in Time multiwavelength program (X-rays to UV) of solar analogs with ages covering 0.1-7 Gyr were reported.
Abstract: We report on the results of the Sun in Time multiwavelength program (X-rays to UV) of solar analogs with ages covering ~0.1-7 Gyr. The chief science goals are to study the solar magnetic dynamo and to determine the radiative and magnetic properties of the Sun during its evolution across the main sequence. The present paper focuses on the latter goal, which has the ultimate purpose of providing the spectral irradiance evolution of solar-type stars to be used in the study and modeling of planetary atmospheres. The results from the Sun in Time program suggest that the coronal X-ray-EUV emissions of the young main-sequence Sun were ~100-1000 times stronger than those of the present Sun. Similarly, the transition region and chromospheric FUV-UV emissions of the young Sun are expected to be 20-60 and 10-20 times stronger, respectively, than at present. When we consider the integrated high-energy emission from 1 to 1200 A, the resulting relationship indicates that about 2.5 Gyr ago the solar high-energy flux was about 2.5 times the present value and about 3.5 Gyr ago was about 6 times the present value (when life supposedly arose on Earth). The strong radiation emissions inferred should have had major influences on the thermal structure, photochemistry, and photoionization of planetary atmospheres and have played an important role in the development of primitive life in the solar system. Some examples of the application of the Sun in Time results on exoplanets and on early solar system planets are discussed.
846 citations
TL;DR: In this paper, the authors suggest that the limitation of C g can be attributed to a space constriction for charge accommodation inside the pore walls, and that the use of extremely high surface area carbons for EDLCs may be unprofitable.
739 citations
TL;DR: It is shown that the spiral breaks spatial inversion symmetry and can account for magnetoelectricity in TbMnO3.
Abstract: ${\mathrm{TbMnO}}_{3}$ is an orthorhombic insulator where incommensurate spin order for temperature ${T}_{N}l41\text{ }\text{ }\mathrm{K}$ is accompanied by ferroelectric order for $Tl28\text{ }\text{ }\mathrm{K}$. To understand this, we establish the magnetic structure above and below the ferroelectric transition using neutron diffraction. In the paraelectric phase, the spin structure is incommensurate and longitudinally modulated. In the ferroelectric phase, however, there is a transverse incommensurate spiral. We show that the spiral breaks spatial inversion symmetry and can account for magnetoelectricity in ${\mathrm{TbMnO}}_{3}$.
663 citations
TL;DR: In this paper, the authors explored the effects that the composition and properties of atmospheric aerosol can have on the activation of droplets in warm clouds, so potentially influencing the magnitude of the indirect effect.
Abstract: The effects of atmospheric aerosol on climate forcing may be very substantial but are quantified poorly at present; in particular, the effects of aerosols on cloud radiative properties, or the "indirect effects" are credited with the greatest range of uncertainty amongst the known causes of radiative forcing. This manuscript explores the effects that the composition and properties of atmospheric aerosol can have on the activation of droplets in warm clouds, so potentially influencing the magnitude of the indirect effect. The effects of size, composition, mixing state and various derived properties are assessed and a range of these properties provided by atmospheric measurements in a variety of locations is briefly reviewed. The suitability of a range of process-level descriptions to capture these aerosol effects is investigated by assessment of their sensitivities to uncertainties in aerosol properties and by their performance in closure studies. The treatment of these effects within global models is reviewed and suggestions for future investigations are made.
656 citations
TL;DR: The X-ray structure of vinblastine bound to tubulin in a complex with the RB3 protein stathmin-like domain (RB3-SLD) explains vin Blastine-induced tubulin self-association into spiral aggregates at the expense of microtubule growth.
Abstract: Vinblastine is one of several tubulin-targeting Vinca alkaloids that have been responsible for many chemotherapeutic successes since their introduction in the clinic as antitumour drugs. In contrast with the two other classes of small tubulin-binding molecules (Taxol and colchicine), the binding site of vinblastine is largely unknown and the molecular mechanism of this drug has remained elusive. Here we report the X-ray structure of vinblastine bound to tubulin in a complex with the RB3 protein stathmin-like domain (RB3-SLD). Vinblastine introduces a wedge at the interface of two tubulin molecules and thus interferes with tubulin assembly. Together with electron microscopical and biochemical data, the structure explains vinblastine-induced tubulin self-association into spiral aggregates at the expense of microtubule growth. It also shows that vinblastine and the amino-terminal part of RB3-SLD binding sites share a hydrophobic groove on the alpha-tubulin surface that is located at an intermolecular contact in microtubules. This is an attractive target for drugs designed to perturb microtubule dynamics by interfacial interference, for which tubulin seems ideally suited because of its propensity to self-associate.
636 citations
TL;DR: In this article, the authors focus on the variation of element concentration between different site types and on the chemical mass closure of atmospheric particulate matter and obtain emission sources of trace elements by evaluation of the element abundances at sites that represent different pollution levels.
564 citations
TL;DR: In this paper, the complete electroweak O(α ) corrections have been calculated for the charged-current four-fermion production processes e + e − → ν τ τ + μ − ν ¯ μ, u d ¯ μ − ǫ c ¯, and u d¯ s c ¯.
529 citations
TL;DR: Nanoparticles are key components in the advancement of future energy technologies, thus, strategies for preparing nanoparticles in large volume by techniques that are cost-effective are required.
Abstract: Nanoparticles are key components in the advancement of future energy technologies, thus, strategies for preparing nanoparticles in large volume by techniques that are cost-effective are required. In the substitution of fossil-fuels by renewable energy resources, nanometer-sized particles play a key role for synthesizing energy vectors from varying and heterogeneous biomass feedstocks. They are extensively used in reformers for the production of hydrogen from solid, liquid, or gaseous energy carriers. Catalyst activities depend critically on their size-dependent properties. Nanoparticles are further indispensable as electrocatalysts in fuel cells and other electrochemical converters. The desire to increase the activity per unit area, and decrease the necessary amount of the expensive catalytic standard, platinum, has spurred innovative approaches for the synthesis of platinum-alloy nanoparticles by wet chemistry, colloidal routes, or physical techniques such as sputtering.
TL;DR: The pencil beam dose model used for treatment planning at the PSI proton gantry, the only system presently applying proton therapy with a beam scanning technique, is presented, including the nuclear beam halo, which can predict quite precisely the dose directly from treatment planning without renormalization measurements.
Abstract: In this paper we present the pencil beam dose model used for treatment planning at the PSI proton gantry, the only system presently applying proton therapy with a beam scanning technique. The scope of the paper is to give a general overview on the various components of the dose model, on the related measurements and on the practical parametrization of the results. The physical model estimates from first physical principles absolute dose normalized to the number of incident protons. The proton beam flux is measured in practice by plane-parallel ionization chambers (ICs) normalized to protons via Faraday-cup measurements. It is therefore possible to predict and deliver absolute dose directly from this model without other means. The dose predicted in this way agrees very well with the results obtained with ICs calibrated in a cobalt beam. Emphasis is given in this paper to the characterization of nuclear interaction effects, which play a significant role in the model and are the major source of uncertainty in the direct estimation of the absolute dose. Nuclear interactions attenuate the primary proton flux, they modify the shape of the depth-dose curve and produce a faint beam halo of secondary dose around the primary proton pencil beam in water. A very simple beam halo model has been developed and used at PSI to eliminate the systematic dependences of the dose observed as a function of the size of the target volume. We show typical results for the relative (using a CCD system) and absolute (using calibrated ICs) dosimetry, routinely applied for the verification of patient plans. With the dose model including the nuclear beam halo we can predict quite precisely the dose directly from treatment planning without renormalization measurements, independently of the dose, shape and size of the dose fields. This applies also to the complex non-homogeneous dose distributions required for the delivery of range-intensity-modulated proton therapy, a novel therapy technique developed at PSI.
TL;DR: HONO can be efficiently formed during the day in the atmosphere at much longer wavelengths compared to the recently proposed nitrate photolysis, and a mechanism is suggested, in which photosensitised electron transfer is occurring.
Abstract: In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present laboratory study, the effect of light (in the range 300–500 nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for organic surfaces encountered in the troposphere (as organic aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on light absorbing aromatic compounds was significantly enhanced when irradiated with light of 300–420 nm, and HONO was formed with high yield when the gas was humidified. Especially organic substrates containing a combination of electron donors, such as phenols, and of compounds yielding excited triplet states, such as aromatic ketones, showed a high reactivity towards NO2. Based on the results reported a mechanism is suggested, in which photosensitised electron transfer is occurring. The results show that HONO can be efficiently formed during the day in the atmosphere at much longer wavelengths compared to the recently proposed nitrate photolysis.
TL;DR: In this paper, the performance of the carbon negative electrode, which is composed of TIMREX SFG synthetic graphite material of varying particle size distribution, was investigated and a transport limitation model was proposed to explain the restrictions of the high current performance of graphite electrodes.
Abstract: The rate capability of various lithium-ion half-cells was investigated. Our study focuses on the performance of the carbon negative electrode, which is composed of TIMREX SFG synthetic graphite material of varying particle size distribution. All cells showed high discharge and comparatively low charge rate capability. Up to the 20 C rate, discharge capacity retention of more than 96% was found for SFG6. The rate capability of the half-cells is a function of both the particle size distribution of the graphite material and the preparation method of the electrode. A transport limitation model is proposed to explain the restrictions of the high current performance of graphite electrodes. The key parameters found to influence the performance of a graphite negative electrode were the loading, the thickness, and the porosity of the electrode.
TL;DR: It is demonstrated that current pulses of different polarity can reversibly and controllably displace a magnetic domain wall (DW) in submicrometer permalloy (NiFe) ring structures.
Abstract: In a combined numerical and experimental study, we demonstrate that current pulses of different polarity can reversibly and controllably displace a magnetic domain wall (DW) in submicrometer permalloy (NiFe) ring structures. The critical current densities for DW displacement are correlated with the specific spin structure of the DWs and are compared to results of micromagnetic simulations including a spin-torque term. Using a notch, an attractive local pinning potential is created for the DW resulting in a highly reproducible spin structure of the DW, critical for reliable current-induced switching.
TL;DR: Molecular dynamics simulations of nanocrystalline copper under shock loading show an unexpected ultrahigh strength behind the shock front, with values up to twice those at low pressure.
Abstract: Molecular dynamics simulations of nanocrystalline copper under shock loading show an unexpected ultrahigh strength behind the shock front, with values up to twice those at low pressure. Partial and perfect dislocations, twinning, and debris from dislocation interactions are found behind the shock front. Results are interpreted in terms of the pressure dependence of both deformation mechanisms active at these grain sizes, namely dislocation-based plasticity and grain boundary sliding. These simulations, together with new shock experiments on nanocrystalline nickel, raise the possibility of achieving ultrahard materials during and after shock loading.
TL;DR: It is shown that mice lacking the chemokine Ccl5 are immune compromised to the point of delayed viral clearance, excessive airway inflammation and respiratory death after mouse parainfluenza or human influenza virus infection.
Abstract: Host defense against viruses probably depends on targeted death of infected host cells and then clearance of cellular corpses by macrophages. For this process to be effective, the macrophage must presumably avoid its own virus-induced death. Here we identify one such mechanism. We show that mice lacking the chemokine Ccl5 are immune compromised to the point of delayed viral clearance, excessive airway inflammation and respiratory death after mouse parainfluenza or human influenza virus infection. Virus-inducible levels of Ccl5 are required to prevent apoptosis of virus-infected mouse macrophages in vivo and mouse and human macrophages ex vivo. The protective effect of Ccl5 requires activation of the Ccr5 chemokine receptor and consequent bilateral activation of G(alphai)-PI3K-AKT and G(alphai)-MEK-ERK signaling pathways. The antiapoptotic action of chemokine signaling may therefore allow scavengers to finally stop the host cell-to-cell infectious process.
TL;DR: In this article, a unique experimental approach for the investigation of two-phase flow phenomena in technical PEFC has been realized, and algorithms for an enhanced quantitative evaluation of the obtained images are presented and successful application to the data demonstrated.
TL;DR: In this paper, a 2-site protolysis nonelectrostatic surface complexation and cation exchange (2SPNE SC/CE) model has been used to model the free energies of aqueous or surface metal complexes and thermodynamic properties of the metal ions or ligands.
TL;DR: This finding limits the use of CD11c‐DTR/GFP mice for the analysis of the role of DC to models and read outs that are proven to be independent of marginal zone and sinusoidal MΦ.
Abstract: To investigate the dependence of individual immunological processes on DC, a transgenic mouse system (CD11c-DTR/GFP mice) has been developed that allows conditional depletion of CD11c+ DC in vivo through administration of diphtheria toxin. We have performed careful histological analysis of CD11c-DTR/GFP mice at different time points after diphtheria toxin injection and confirmed the transient depletion of CD11c+ cells from lymph nodes and spleen. Unexpectedly, the injection of diphtheria toxin completely depleted marginal zone and metallophilic M(Phi) from the spleen and their sinusoidal counterparts from the lymph nodes. This finding limits the use of CD11c-DTR/GFP mice for the analysis of the role of DC to models and read outs that are proven to be independent of marginal zone and sinusoidal M(Phi).
TL;DR: In this paper, the authors present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters, which enables a detailed description of mass transport and chemical reactions at the gas-particle interface, and allows linking aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes.
Abstract: Aerosols and clouds play central roles in atmospheric chemistry and physics, climate, air pollution, and public health. The mechanistic understanding and predictability of aerosol and cloud properties, interactions, transformations, and effects are, however, still very limited. This is due not only to the limited availability of measurement data, but also to the limited applicability and compatibility of model formalisms used for the analysis, interpretation, and description of heterogeneous and multiphase processes. To support the investigation and elucidation of atmospheric aerosol and cloud surface chemistry and gas-particle interactions, we present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters. It enables a detailed description of mass transport and chemical reactions at the gas-particle interface, and it allows linking aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes. The key elements and essential aspects of the presented framework are: a simple and descriptive double-layer surface model (sorption layer and quasi-static layer); straightforward flux-based mass balance and rate equations; clear separation of mass transport and chemical reactions; well-defined and consistent rate parameters (uptake and accommodation coefficients, reaction and transport rate coefficients); clear distinction between gas phase, gas-surface, and surface-bulk transport (gas phase diffusion, surface and bulk accommodation); clear distinction between gas-surface, surface layer, and surface-bulk reactions (Langmuir-Hinshelwood and Eley-Rideal mechanisms); mechanistic description of concentration and time dependences (transient and steady-state conditions); flexible addition of unlimited numbers of chemical species and physicochemical processes; optional aggregation or resolution of intermediate species, sequential processes, and surface layers; and full compatibility with traditional resistor model formulations. The outlined double-layer surface concept and formalisms represent a minimum of model complexity required for a consistent description of the non-linear concentration and time dependences observed in experimental studies of atmospheric multiphase processes (competitive co-adsorption and surface saturation effects, etc.). Exemplary practical applications and model calculations illustrating the relevance of the above aspects are presented in a companion paper (Ammann and Poschl, 2007). We expect that the presented model framework will serve as a useful tool and basis for experimental and theoretical studies investigating and describing atmospheric aerosol and cloud surface chemistry and gas-particle interactions. It shall help to end the "Babylonian confusion" that seems to inhibit scientific progress in the understanding of heterogeneous chemical reactions and other multiphase processes in aerosols and clouds. In particular, it shall support the planning and design of laboratory experiments for the elucidation and determination of fundamental kinetic parameters; the establishment, evaluation, and quality assurance of comprehensive and self-consistent collections of rate parameters; and the development of detailed master mechanisms for process models and derivation of simplified but yet realistic parameterizations for atmospheric and climate models.
University of Lisbon1, University of Cambridge2, Texas A&M University3, Florida State University4, Johns Hopkins University5, Argonne National Laboratory6, University of Wisconsin-Madison7, Lawrence Berkeley National Laboratory8, University of Vienna9, Stanford University10, Michigan State University11, Royal Holloway, University of London12, Moscow State University13, Fermilab14, Chonbuk National University15, CERN16, University of Freiburg17, Pontifical Catholic University of Chile18, University of Paris19, University of Delhi20, Austrian Academy of Sciences21, National Autonomous University of Mexico22, University of Würzburg23, University of Zurich24, Max Planck Society25, Indian Institute of Science26, Aristotle University of Thessaloniki27, University of Barcelona28, University of California, Davis29, University of Tokushima30, University of California, Santa Cruz31, University of Science and Technology of China32, Tsinghua University33, Uppsala University34, Tokyo Gakugei University35, Spanish National Research Council36, National Taiwan University37, University of Liverpool38, University of Warsaw39, University of Michigan40, Seoul National University41, Yonsei University42, University of Southampton43, University of Bonn44, University of Montpellier45, RWTH Aachen University46, Laboratoire d'Annecy-le-Vieux de physique des particules47, University of Pennsylvania48, Carleton University49, University of Florida50, University of Glasgow51, University of Tokyo52, University of Lyon53, Harish-Chandra Research Institute54, University of Colorado Boulder55, Kyoto University56, University of Minnesota57, University of Rochester58, Durham University59, Tata Institute of Fundamental Research60, Paul Scherrer Institute61, University of Hamburg62, Chung-Ang University63, University of Sheffield64, University of Chicago65, Tohoku University66, Peking University67
TL;DR: In this article, a supersymmetry Parameter Analysis SPA (SPA) scheme is proposed based on a consistent set of conventions and input parameters, which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e+e-linear collider experiments.
Abstract: High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e+e- linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.
TL;DR: This Letter shows that hitherto unaccounted spin selection rules give rise to a highly nonadiabatic behavior in the O(2)/Al(111) interaction, and discusses problems caused by the insufficient accuracy of present-day exchange-correlation functionals.
Abstract: A most basic and puzzling enigma in surface science is the description of the dissociative adsorption of O(2) at the (111) surface of Al. Already for the sticking curve alone, the disagreement between experiment and results of state-of-the-art first-principles calculations can hardly be more dramatic. In this Letter we show that this is caused by hitherto unaccounted spin selection rules, which give rise to a highly nonadiabatic behavior in the O(2)/Al(111) interaction. We also discuss problems caused by the insufficient accuracy of present-day exchange-correlation functionals.
TL;DR: Evidence for oligomer formation for SOA from both precursors was given by an increasing abundance of compounds with a high molecular weight and by an increase thermal stability with increasing aging time.
Abstract: Secondary organic aerosol (SOA) formation from the photooxidation of an anthropogenic (1,3,5-trimethylbenzene) and a biogenic (alpha-pinene) precursor was investigated at the new PSI smog chamber. The chemistry of the gas phase was followed by proton transfer reaction mass spectrometry, while the aerosol chemistry was investigated with aerosol mass spectrometry, ion chromatography, laser desorption ionization mass spectrometry, and infrared spectroscopy, along with volatility and hygroscopicity studies. Evidence for oligomer formation for SOA from both precursors was given by an increasing abundance of compounds with a high molecular weight (up to 1000 Da) and by an increasing thermal stability with increasing aging time. The results were compared to data obtained from ambient aerosol samples, revealing a number of similar features.
TL;DR: In this paper, a comparison of radiocarbon-based and independent geomagnetic field reconstructions is made, showing that changes in the carbon cycle significantly influenced the atmospheric radioccarbon concentration before 10,000 years BP.
TL;DR: In this article, a semi-empirical many-body interatomic potential for large-scale molecular dynamics simulations of magnetic α-iron was derived using a combination of the Stoner and the Ginzburg-Landau models.
Abstract: We develop a semi-empirical many-body interatomic potential suitable for large scale molecular dynamics simulations of magnetic α-iron. The functional form of the embedding part of the potential is derived using a combination of the Stoner and the Ginzburg–Landau models. We show that it is the symmetry broken solutions of the Ginzburg–Landau model describing spontaneous magnetization of atoms that provide the link between magnetism and interatomic forces. We discuss a range of potential applications of the new method.
TL;DR: A new type of nano-sized silicon/carbon composite shows superior electrochemical cycling properties as negative electrode material for possible use in lithium-ion batteries with respect to high reversible and low irreversible capacity, and low fading.
TL;DR: In this paper, the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis.
Abstract: The cost of polymer electrolyte fuel cell (PEFC) components is crucial to the commercial viability of the technology. Proton exchange membranes fabricated via the method of radiation grafting offer a cost-competitive option, because starting materials are inexpensive commodity products and the preparation procedure is based on established industrial processes. Radiation grafted membranes have been used with commercial success in membrane separation technology. This review focuses on the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis. The application in hydrogen and methanol fuelled cells is treated separately. Optimized styrene / crosslinker grafted and sulfonated membranes show performance comparable to perfluorinated membranes. Some properties, such as methanol permeability, can be tailored to be superior. Durability of several thousand hours at practical operating conditions has been demonstrated. Alternative styrene derived monomers with higher chemical stability offer the prospect of enhanced durability or higher operating temperature.
TL;DR: In this paper, the reaction kinetics of MoSe2 formation were investigated by selenizing Mo layers in Se vapor at different temperatures and for different durations, and it was found that in all samples, a homogeneous MoSe 2 layer is formed on top of the Mo layer.
TL;DR: In this paper, the dependence of the surface structure, composition, and electronic properties of three low index surfaces on the annealing temperature in vacuum has been investigated experimentally by low energy ion scattering spectroscopy (LEIS), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle resolved valence band photoemission (ARUPS) using synchrotron radiation.
Abstract: The dependence of the surface structure, composition, and electronic properties of three low index $\mathrm{Sn}{\mathrm{O}}_{2}$ surfaces on the annealing temperature in vacuum has been investigated experimentally by low energy ${\mathrm{He}}^{+}$ ion scattering spectroscopy (LEIS), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle resolved valence band photoemission (ARUPS) using synchrotron radiation. Transitions from stoichiometric to reduced surface phases have been observed at $440--520\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, $610--660\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, and $560--660\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for the $\mathrm{Sn}{\mathrm{O}}_{2}$ (110), (100), and (101) surfaces, respectively. Density functional theory has been employed to assess the oxidation state and stability of different surface structures and compositions at various oxygen chemical potentials. The reduction of the $\mathrm{Sn}{\mathrm{O}}_{2}$ surfaces is facilitated by the dual valency of Sn, and for all three surfaces a transition from Sn(IV) to Sn(II) is observed. For the (100) and (101) surfaces, theory supports the experimental observations that the phase transitions are accomplished by removal of bridging oxygen atoms from a stoichiometric $\mathrm{Sn}{\mathrm{O}}_{2}$ surface, leaving a SnO surface layer with a $1\ifmmode\times\else\texttimes\fi{}1$ periodicity. For the (110) surface the lowest energy surface under reducing conditions was predicted for a model with a SnO surface layer with all bridging oxygen and every second row of in-plane oxygen atoms removed. Ab initio atomistic thermodynamic calculations predict the phase transition conditions for the (101) surface, but there are significant differences with the experimentally observed transition temperatures for the (110) and (100) surfaces. This discrepancy between experiment and thermodynamic equilibrium calculations is likely because of a dominant role of kinetic processes in the experiment. The reduction of surface Sn atoms from a Sn(IV) to a Sn(II) valence state results in filling of the $\mathrm{Sn}\text{\ensuremath{-}}5s$ states and, consequently, the formation of Sn derived surface states for all three investigated surfaces. The dispersion of the surface states for the reduced (101) surface was determined and found to be in good agreement with the DFT results. For the (110) surface, the $4\ifmmode\times\else\texttimes\fi{}1$ reconstruction that forms after sputter and annealing cycles was also investigated. For this surface, states that span almost the entire band gap were observed. Resonant photoemission spectroscopy identified all the surface states on the reduced $\mathrm{Sn}{\mathrm{O}}_{2}$ surfaces as Sn derived.