CONCEPTUAL DESIGN REPORT

Brookhaven National Laboratory has prepared a conceptual design for a world class user facility for scientific research using synchrotron radiation. This facility, called the ''National Synchrotron Light Source II'' (NSLS-II), will provide ultra high brightness and flux and exceptional beam stability. It will also provide advanced insertion devices, optics, detectors, and robotics, and a suite of scientific instruments designed to maximize the scientific output of the facility. Together these will enable the study of material properties and functions with a spatial resolution of {approx}1 nm, an energy resolution of {approx}0.1 meV, and the ultra high sensitivity required to perform spectroscopy on a single atom. The overall objective of the NSLS-II project is to deliver a research facility to advance fundamental science and have the capability to characterize and understand physical properties at the nanoscale, the processes by which nanomaterials can be manipulated and assembled into more complex hierarchical structures, and the new phenomena resulting from such assemblages. It will also be a user facility made available to researchers engaged in a broad spectrum of disciplines from universities, industries, and other laboratories

2nd International Planetary Probe Workshop

Included are presentations from the 2nd International Planetary Probe Workshop. The purpose of the second workshop was to continue to unite the community of planetary scientists, spacecraft engineers and mission designers and planners; whose expertise, experience and interests are in the areas of entry probe trajectory and attitude determination, and the aerodynamics/aerothermodynamics of planetary entry vehicles. Mars lander missions and the first probe mission to Titan made 2004 an exciting year for planetary exploration. The Workshop addressed entry probe science, engineering challenges, mission design and instruments, along with the challenges of reconstruction of the entry, descent and landing or the aerocapture phases. Topics addressed included methods, technologies, and algorithms currently employed; techniques and results from the rich history of entry probe science such as PAET, Venera/Vega, Pioneer Venus, Viking, Galileo, Mars Pathfinder and Mars MER; upcoming missions such as the imminent entry of Huygens and future Mars entry probes; and new and novel instrumentation and methodologies

The Structure and Dynamics of Ions at Aqueous Interfaces Studied via Atomic Force Microscopy

The organisation and kinetics of charges at solid and soft interfaces play a central role in biological signalling processes and are vital for energy storage technologies as well as our understanding of heterogeneous catalysis. At the molecular-scale, such interfacial behaviour remains stubbornly difficult to characterise, due to the short-ranged interactions between ions, their aqueous solvent and surface groups. Thus, continuum-scale models quickly break down, especially close to the interface and with high charge densities. This thesis addresses the question of ionic organisation using atomic force microscopy (AFM), which uniquely combines sub-nanometre spatial resolution and the ability to probe relatively long timescales. The use of small oscillation amplitudes allows the topography of the ionic layer to be mapped while simultaneously extracting physical properties from the sample or the interface itself, with time resolution spanning from tens of milliseconds to minutes. The structure of ions at hydrophilic interfaces is shown to be delicately sensitive to the charges’ molecular structure (in the case of larger buffering agents) and their charge density (for simple alkali cations). Specifically, the cations’ interactions with a model lipid membrane and the waters around it lead to an attractive correlation energy which generates nanoscale networks that evolve over the course of many seconds. These ionic structures directly reduce the effective stiffness of the lipids, providing a mechanism for the spontaneous control of membranes’ mechanical properties. These ionic networks are significant in the case of confined fluids and provide an efficient means of lubrication even under high pressures in sub-nanometre gaps. When sheared, such fluid films are revealed to be non-Newtonian, with dynamics that depend on the velocity and lengthscale of the motion. The results highlight the greatly damped kinetics of ions and water molecules at interfaces, and shed light on the mechanisms behind their transport through and along biomolecules

Experimental evidence for the quantum condensation of ultracold dipolar excitons

In this thesis, we report experimental evidence of a "gray" condensate of excitons, as predicted theoretically by M. Combescot et al. Most importantly, the condensate is characterized by the macroscopic population of dark excitons coherently coupled to a weak population of bright excitons through fermion exchanges. Such quantum condensation results from the excitons internal structure, with a dark i.e. optically inactive ground state. It is actually very similar to what occurs in the phases of superfluid 3He or in the more recent spinor condensates of ultracold atomic Bose gases. While it is our belief that such a "gray" condensate will eventually be observed in other excitonic systems, our study focus on its appearance together with the macroscopic auto-organization of dipolar excitons. Precisely we emphasize fragmented exciton rings in an electrically biased GaAs single quantum well. This very striking pattern was first observed independently by the groups of L. Butov and D. Snoke. It was interpreted as the result of an ambipolar diffusion of carriers in the quantum wells. The fragmentation of the macrosopic ring observed at low temperature by Butov and coworkers, and the subsequent evidence for long-range spatial coherence together with complex pattern of polarization, led Butov et al. to interpret the fragmentation as an evidence for the transition to a quantum regime where coherent exciton transport dominates. Our experiments led us to a very different interpretation. Indeed, we show that for our sample the formation of the fragmented ring is dominated by the diffusion of dipolar excitons in an optically induced electrostatic landscape. This potential landscape arises from the modulation of the internal electric field by excess charges injected in the QW by the same excitation beam which induces the ring. Dipolar excitons then explore a potential landscape characterized by a wide anti-trap inside the ring and more strikingly by microscopic traps distributed along the circumference of the ring. There, i.e. in the outside vicinity of the ring, a confining potential is responsible for the formation of "islands" where the population of dark excitons is dominant. Due to the low energy splitting between the bright and dark excitonic states in our sample, the observation of a dominant population of dark excitons signals that excitons condense in the low-lying dark states. To confirm this interpretation we show that the weak photoluminescence emitted in the outer vicinity exhibits macroscopic spatial coherence, up to 10 times larger than the de Broglie wavelength. Islands of extended coherence are in fact identified and quickly disappear upon increase of the bath temperature. This leads to an evolution of the coherence length strongly dependent on the temperature. Finally, we show that the photoluminescence emitted in the vicinity of the fragmented ring is dominantly linearly polarized and also organized in islands outside the ring. All these observations confirm the predicted signatures of a "gray" condensate, as formulated by M. and R. Combescot.En aquesta tesis, mostrem evidència experimental d'un condensat "gris" d'excitons, tal com prediu la teoria de M. Combescot et al. En particular, el condensat està caracteritzat per la població macroscòpica d'excitons foscos acoblats coherentment a una població baixa d'excitons brillants a través d'intercanvis fermiònics. Aquesta condensació quàntica es dóna com a resultat de l'estructura interna dels excitons, amb un estat fonamental fosc i.e. òpticament inactiu. És de fet molt similar al que passa en les fases de 3He superfluid o en els més recents condensats d'espinors de gasos atòmics ultrafreds de Bose. Encara que nosaltres creiem que un condensat "gris" serà eventualment observat en altres sistemes excitònics, el nostre estudi es focalitza en la seva manifestació juntament amb l'auto-organització macroscòpica d'excitons dipolars. Precisament, ens centrem en els anells excitònics fragmentats en un sol pou quàntic elèctricament polaritzat. Aquest sorprenent patró va ser observat independentment per primer cop pels grups de L. Butanov i D. Snoke. Va ser interpretat com el resultat d'una difusió ambipolar de portadors en pous quàntics. La fragmentació de l'anell macroscòpic observada a baixes temperatures per Butov i els seus col.laboradors, i la posterior evidència de coherència espacial de llarg abast juntament amb un patró de polarització complex, va portar a Butov et al. a interpretar la fragmentació com una evidència de la transició cap al règim quàntic en el que domina el transport coherent d'excitons. El nostre experiment ens va portar cap una interpretació molt diferent. En efecte, mostrem que per la nostra mostra la formació d'anells fragmentats és dominada per la difusió d'excitacions dipolars en un perfil electrostàtic òpticament induït. Aquest perfil de potencial sorgeix de la modulació del camp elèctric intern per un excés de càrregues injectades en el PQ pel mateix feix d'excitació que indueix l'anell. Les excitacions dipolars exploren per tant un perfil de potencial caracteritzat per una anti-trampa ampla dins de l'anell i més sorprenentment per trampes microscòpiques distribuïdes al llarg de la circumferència de l'anell. Allà, i.e. en la proximitat exterior de l'anell, un potencial de confinament és el responsable de la formació d'"illes" on la població d'excitons foscos és dominant. Degut a la baixa separació energètica entre els estats excitònics brillant i fosc en la nostra mostra, l'observació d'una població dominant d'excitons foscos senyala que els excitons es condensen en els estats foscos de més baixa energia. Per tal de confirmar aquesta interpretació, mostrem que la dèbil fotoluminescència emesa en la proximitat exterior exhibeix coherència espacial macroscòpica, fins a 10 vegades major que la longitud d'ona de de Broglie. Illes de coherència ampliada són de fet identificades i desapareixen ràpidament en incrementar la temperatura del focus. Això porta cap a una evolució de la longitud de coherència que depèn fortament de la temperatura. Finalment, mostrem que la fotoluminescència emesa en la proximitat de l'anell fragmentat està dominantment polaritzada linealment i organitzada també en illes fora de l'anell. Totes les observacions confirmen les senyals característiques previstes per un condensat "gris", tal com està formulat en la teoria desenvolupada per M. i R. Combesco

Low Dose Analytical Electron Microscopy of Hybrid Perovskite Photovoltaic Devices

The rapid ascent of perovskite photovoltaics over the past decade has enabled this technology to now stand on the cusp of commercialisation. However, a successful entry into the market will only be feasible if the power conversion efficiencies of perovskite solar modules can at least approach those of laboratory-scale cells. Achieving this feat requires spatially homogeneous depositions of device layers over a large area and high-quality interconnections between adjacent cells in a module. Since perovskite photovoltaic devices are nanostructured, materials characterisation with a nanometre spatial resolution can provide valuable insights to optimise the processes involved in scalable film deposition and interconnection fabrication. This thesis presents nanoscale electron microscopy investigations of perovskite photovoltaic devices made using scalable deposition methods and the cell interconnections within. A characterisation workflow consisting of cross-sectional specimen preparation, data acquisition, and multivariate statistical data analysis is developed and validated. Preparation of electron-transparent specimens is performed using focused ion beam milling, which is shown to have minimum impact on the perovskite specimen. Nanoscale compositional mapping is performed using energy-dispersive X-ray spectroscopy in a scanning transmission electron microscope, where the applied electron dose is minimised to suppress beam-induced specimen damage while still ensuring statistical significance in the data. Principal component analysis, a multivariate statistical analysis algorithm, is optimised and applied to improve the signal-to-noise ratio in the obtained datasets by an order of magnitude. This sequence allows acquisition of spatially resolved morphological and compositional data with minimum damage on the perovskite specimen, which are supported by complementary computational methods and other characterisation techniques. The optimised workflow is applied to study perovskite solar modules deposited by blade coating, where electron microscopy revealed how additives in the perovskite precursor solutions contribute towards a more homogeneous device stack and, ultimately, more efficient modules. Finally, the interconnections are studied as they are critical to ensure good electrical performance in solar modules. Compositional characterisation shows how laser pulses used in scribing the interconnection lines can decompose the perovskite layer next to those lines, and also how the decomposition is affected by the perovskite’s homogeneity. Furthermore, elemental mapping reveals diffusion of sodium from the glass substrate into the active layers through the interconnection lines, even before the devices are operated. Sodium diffusion results in passivated defect sites and stronger perovskite luminescence, but also carries an inherent risk of excessive diffusion throughout the device’s lifetime.Jardine Foundation; Cambridge Trus

Analysis of design strategies for RF ESD problems in CMOS circuits

This thesis analyses the design strategies used to protect RF circuits that are implemented in CMOS technologies. It investigates, in detail, the physical mechanisms involved when a ggNMOS structure is exposed to an ESD event and undergoes snapback. The understanding gained is used to understand why the performance of the current RF ESD clamp is poor and suggestions are made as to how the performance of ggNMOS clamps can be improved beyond the current body of knowledge. The ultimate aim is to be able to design effective ESD protection clamps whilst minimising the effect the circuit has on RF I/O signals. A current ggNMOS based RF ESD I/O protection circuit is analysed in detail using a Transmission Line Pulse (TLP) tester. This is shown to be a very effective diagnostic tool by showing many characteristics of the ggNMOS during the triggering and conducting phase of the ESD event and demonstrate deficiencies in the clamp design. The use of a FIB enhances the analysis by allowing the isolation of individual components in the circuit and therefore their analysis using the TLP tester. SPICE simulations are used to provide further commentary on the debate surrounding the specification required of a TLP tester for there to be a good correlation between a TLP test and the industry standard Human Body Model (HBM) ESD test. Finite element simulations are used to probe deeper in to the mechanisms involved when a ggNMOS undergoes snapback especially with regard to the contribution parasitic components within the ggNMOS make to the snapback process. New ggNMOS clamps are proposed which after some modification are shown to work. Some of the finite element experiments are repeated in a 0.18μπ7. process CMOS test chip and a comparison is made between the two sets of results. In the concluding chapter understanding that has been gained from previous chapters is combined with the published body of knowledge to suggest and explain improvements in the design of a ggNMOS for RF and standard applications. These improvements will improve homogeneity of ggNMOS operation thus allowing the device size to be reduced and parasitic loading for a given ESD performance. These techniques can also be used to ensure that the ESD current does not take an unintended path through the chip

Imagerie thermique et thermoélastique de circuits intégrés : application à l'analyse de défaillances

Ce travail décrit le développement d’une instrumentation en mesures thermiques et thermoélastiques pour l’analyse de défaillance sur circuits intégrés, il comporte trois parties : La première partie concerne des mesures interférométriques effectuées avec deux interféromètres, homodyne et hétérodyne. Ces interféromètres seront appliqués pour la détection de points chauds sur des circuits défaillants. La deuxième partie concerne des mesures thermiques effectuées en thermoréflectance. Deux bancs de mesure ont été développés : - le premier s’applique pour l’imagerie face avant. - le deuxième entièrement original, concerne l’imagerie large champ face arrière qui utilise une porte optique temporelle. La dernière partie concerne le développement d’une nouvelle approche pour les mesures de température et déplacement en utilisant la microscopie à balayage laser, avec une étude de résolution et sensibilité.This work describes the development of instrumentation in thermal and thermoelastic measurements for failure localisation and test diagnostic. It is divided in three parts: The first part is about interferometric measurements done with homodyne and heterodyne interferometers. Those interferometers were applied for defects localisation in failures ICs. The second part is about thermal measurements done with thermoreflectance. Two experimental benches were developed: - the first is applied for front side imaging - the second is a new technique applied for back side imaging, which is based on time gating. The last part of this work is about the development of a new approach for thermal and thermelastic measurements with the use of light scanning microscopy. It includes a study of the resolution and the sensitivity

Non-covalent interactions in organotin(IV) derivatives of 5,7-ditertbutyl- and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine as recognition motifs in crystalline self- assembly and their in vitro antistaphylococcal activity

Non-covalent interactions are known to play a key role in biological compounds due to their stabilization of the tertiary and quaternary structure of proteins [1]. Ligands similar to purine rings, such as triazolo pyrimidine ones, are very versatile in their interactions with metals and can act as model systems for natural bio-inorganic compounds [2]. A considerable series (twelve novel compounds are reported) of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) and 5,7-diphenyl- 1,2,4-triazolo[1,5-a]pyrimidine (dptp) were synthesized and investigated by FT-IR and 119Sn M\uf6ssbauer in the solid state and by 1H and 13C NMR spectroscopy, in solution [3]. The X-ray crystal and molecular structures of Et2SnCl2(dbtp)2 and Ph2SnCl2(EtOH)2(dptp)2 were described, in this latter pyrimidine molecules are not directly bound to the metal center but strictly H-bonded, through N(3), to the -OH group of the ethanol moieties. The network of hydrogen bonding and aromatic interactions involving pyrimidine and phenyl rings in both complexes drives their self-assembly. Noncovalent interactions involving aromatic rings are key processes in both chemical and biological recognition, contributing to overall complex stability and forming recognition motifs. It is noteworthy that in Ph2SnCl2(EtOH)2(dptp)2 \u3c0\u2013\u3c0 stacking interactions between pairs of antiparallel triazolopyrimidine rings mimick basepair interactions physiologically occurring in DNA (Fig.1). M\uf6ssbauer spectra suggest for Et2SnCl2(dbtp)2 a distorted octahedral structure, with C-Sn-C bond angles lower than 180\ub0. The estimated angle for Et2SnCl2(dbtp)2 is virtually identical to that determined by X-ray diffraction. Ph2SnCl2(EtOH)2(dptp)2 is characterized by an essentially linear C-Sn-C fragment according to the X-ray all-trans structure. The compounds were screened for their in vitro antibacterial activity on a group of reference staphylococcal strains susceptible or resistant to methicillin and against two reference Gramnegative pathogens [4] . We tested the biological activity of all the specimen against a group of staphylococcal reference strains (S. aureus ATCC 25923, S. aureus ATCC 29213, methicillin resistant S. aureus 43866 and S. epidermidis RP62A) along with Gram-negative pathogens (P. aeruginosa ATCC9027 and E. coli ATCC25922). Ph2SnCl2(EtOH)2(dptp)2 showed good antibacterial activity with a MIC value of 5 \u3bcg mL-1 against S. aureus ATCC29213 and also resulted active against methicillin resistant S. epidermidis RP62A

Apollo-Soyuz test project. Volume 1: Astronomy, earth atmosphere and gravity field, life sciences, and materials processing

The joint U.S.-USSR experiments and the U.S. conducted unilateral experiments performed during the Apollo Soyuz Test Project are described. Scientific concepts and experiment design and operation are discussed along with scientific results of postflight analysis