Pressure-Induced Phase Transformation, Reversible Amorphization, and Anomalous Visible Light Response in Organolead Bromide Perovskite
Abstract not provided
Wang, Yonggang↗
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Moisture‐Budget Drivers of Global Projections of Meteorological Drought From Multiple GCM Large Ensembles
Future projections of global meteorological drought are evaluated in the Multi‐Model Large Ensemble Archive, including an evaluation of the atmospheric moisture budget, conditioned on drought years. Drought is defined as 5‐year running‐mean annual precipitation below some threshold, for example, 10th percentile. Drought increases in frequency over the subtropics, in addition to certain tropical regions, consistent with previous studies. Here, the moisture‐budget decomposition allows drought to be defined as mean‐flow, eddy, or feedback droughts, depending on which term in the equation contributes the largest negative interannual anomaly. In the historical climate, mean‐flow droughts constitute most droughts at low latitudes; eddy droughts are equally common at higher latitudes; feedback droughts (i.e., droughts exacerbated by land–atmosphere feedbacks) constitute almost all droughts in water‐limited subtropical/Mediterranean regions. The future drought increases are predominantly due to increases in feedback droughts in regions where these droughts are common historically but also over the Amazon. However, over most Mediterranean‐type regions mean‐flow droughts are also large contributors, resulting from dynamics. Eddy droughts also contribute to future increases along the equatorward flanks of historical eddy‐driven jets, likely reflecting poleward shifts therein. Model uncertainty is particularly large over the Amazon and Australia, a reflection of model diversity in processes associated with land‐atmosphere interaction. Based on these results, an availability of 3‐D atmospheric data from a wider swath of global climate model large ensembles could help constrain global drought projections based on the representation of drought mechanisms in the historical climate.
54 ENVIRONMENTAL SCIENCES↗
Embedded argon as a tool for sampling local structure in thin plasma deposited aluminum oxide films
Al{sub 2}O{sub 3} thin films, either amorphous or of varying degrees of crystallinity, were deposited by two-frequency radio-frequency magnetron sputtering. Film crystallinity was investigated by Fourier transform infrared spectroscopy and X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the amount of Ar naturally trapped within the films during the deposition process. A clear correlation was found between the existence of crystalline phases, as determined by XRD, and a shift towards lower binding energy positions of the Ar2p core levels of embedded gas. The shift is due to differences in the local Al{sub 2}O{sub 3} matrix (amorphous or crystalline) of the embedded gas, thus, providing an XPS fingerprint that can be used to qualitatively determine the presence or absence of crystalline phases in very thin films.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing
This work isolated the cause of the observed discrepancy between the electron temperature (T{sub e}) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the stray light filters transmission functions due to the variations in the incidence angles of the collected photons impacted plasma measurements. To correct for this identified source of error, correction factors were developed using ray tracing models for the calibration and operational states of the diagnostic. The application of these correction factors resulted in an increase in the observed T{sub e}, resulting in the partial if not complete removal of the observed discrepancy in the measured T{sub e} between the JET core LIDAR TS diagnostic, High Resolution Thomson Scattering, and the Electron Cyclotron Emission diagnostics.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy
Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Origin of core-to-core x-ray emission spectroscopy sensitivity to structural dynamics
Recently, coherent structural dynamics in the excited state of an iron photosensitizer was observed through oscillations in the intensity of Kα x-ray emission spectroscopy (XES). Understanding the origin of the unexpected sensitivity of core-to-core transitions to structural dynamics is important for further development of femtosecond time-resolved XES methods and, we believe, generally necessary for interpretation of XES signals from highly non-equilibrium structures that are ubiquitous in photophysics and photochemistry. Here, we use multiconfigurational wavefunction calculations combined with atomic theory to analyze the emission process in detail. The sensitivity of core-to-core transitions to structural dynamics is due to a shift of the minimum energy metal–ligand bond distance between 1s and 2p core-hole states. A key effect is the additional contraction of the non-bonding 3s and 3p orbitals in 1s core-hole states, which decreases electron– electron repulsion and increases overlap in the metal–ligand bonds. The effect is believed to be general and especially pronounced for systems with strong bonds. The important role of 3s and 3p orbitals is consistent with the analysis of radial charge and spin densities and can be connected to the negative chemical shift observed for many transition metal complexes. The XES sensitivity to structural dynamics can be optimized by tuning the emission energy spectrometer, with oscillations up to ±4% of the maximum intensity for the current system. The theoretical predictions can be used to design experiments that separate electronic and nuclear degrees of freedom in ultrafast excited state dynamics.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
COSMIC SHEAR RESULTS FROM THE DEEP LENS SURVEY. I. JOINT CONSTRAINTS ON {Omega} {sub M} AND {sigma}{sub 8} WITH A TWO-DIMENSIONAL ANALYSIS
We present a cosmic shear study from the Deep Lens Survey (DLS), a deep BVRz multi-band imaging survey of five 4 deg{sup 2} fields with two National Optical Astronomy Observatory (NOAO) 4 m telescopes at Kitt Peak and Cerro Tololo. For both telescopes, the change of the point-spread-function (PSF) shape across the focal plane is complicated, and the exposure-to-exposure variation of this position-dependent PSF change is significant. We overcome this challenge by modeling the PSF separately for individual exposures and CCDs with principal component analysis (PCA). We find that stacking these PSFs reproduces the final PSF pattern on the mosaic image with high fidelity, and the method successfully separates PSF-induced systematics from gravitational lensing effects. We calibrate our shears and estimate the errors, utilizing an image simulator, which generates sheared ground-based galaxy images from deep Hubble Space Telescope archival data with a realistic atmospheric turbulence model. For cosmological parameter constraints, we marginalize over shear calibration error, photometric redshift uncertainty, and the Hubble constant. We use cosmology-dependent covariances for the Markov Chain Monte Carlo analysis and find that the role of this varying covariance is critical in our parameter estimation. Our current non-tomographic analysis alone constrains the {Omega} {sub M}-{sigma}{sub 8} likelihood contour tightly, providing a joint constraint of {Omega} {sub M} = 0.262 {+-} 0.051 and {sigma}{sub 8} = 0.868 {+-} 0.071. We expect that a future DLS weak-lensing tomographic study will further tighten these constraints because explicit treatment of the redshift dependence of cosmic shear more efficiently breaks the {Omega} {sub M}-{sigma}{sub 8} degeneracy. Combining the current results with the Wilkinson Microwave Anisotropy Probe 7 year (WMAP7) likelihood data, we obtain {Omega} {sub M} = 0.278 {+-} 0.018 and {sigma}{sub 8} = 0.815 {+-} 0.020.
79 ASTRONOMY AND ASTROPHYSICS↗
Gravitational waves and stalled satellites from massive galaxy mergers at z ≤ 1
We present a model for merger-driven evolution of the mass function for massive galaxies and their central supermassive black holes at late times. We discuss the current observational evidence in favor of merger-driven massive galaxy evolution during this epoch, and demonstrate that the observed evolution of the mass function can be reproduced by evolving an initial mass function under the assumption of negligible star formation. We calculate the stochastic gravitational wave signal from the resulting black hole binary mergers in the low redshift universe (z ≤ 1) implied by this model, and find that this population has a signal-to-noise ratio 2 × to 5 × larger than previous estimates for pulsar timing arrays, with a (2σ, 3σ) lower limit within this model of h{sub c}(f = 1 yr{sup –1}) = (1.1 × 10{sup –15}, 6.8 × 10{sup –16}). The strength of this signal is sufficient to make it detectable with high probability under conservative assumptions within the next several years. A principle reason that this result is larger than previous estimates is our use of a recent recalibration of the black hole-stellar mass correlation for the brightest cluster galaxies, which increases our estimate by a factor of ∼2 relative to past results. For cases where a galaxy merger fails to lead to a black hole merger, we estimate the probability for a given number of satellite black holes to remain within a massive host galaxy, and interpret the result in light of ULX observations. We find that in rare cases, wandering supermassive black holes may be bright enough to appear as ULXs.
79 ASTRONOMY AND ASTROPHYSICS↗
3C 220.3: A radio galaxy lensing a submillimeter galaxy
Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1''.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1''.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1''.02) and B (0''.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, M/L{sub i}∼8±4 M{sub ⊙} L{sub ⊙}{sup −1}, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a dust-enshrouded nucleus.
79 ASTRONOMY AND ASTROPHYSICS↗
Stochastic microhertz gravitational radiation from stellar convection
High Reynolds-number turbulence driven by stellar convection in main-sequence stars generates stochastic gravitational radiation. We calculate the wave-strain power spectral density as a function of the zero-age main-sequence mass for an individual star and for an isotropic, universal stellar population described by the Salpeter initial mass function and redshift-dependent Hopkins-Beacom star formation rate. The spectrum is a broken power law, which peaks near the turnover frequency of the largest turbulent eddies. The signal from the Sun dominates the universal background. For the Sun, the far-zone power spectral density peaks at S(f {sub peak}) = 5.2 × 10{sup –52} Hz{sup –1} at frequency f {sub peak} = 2.3 × 10{sup –7} Hz. However, at low observing frequencies f < 3 × 10{sup –4} Hz, the Earth lies inside the Sun's near zone and the signal is amplified to S {sub near}(f {sub peak}) = 4.1 × 10{sup –27} Hz{sup –1} because the wave strain scales more steeply with distance (∝d {sup –5}) in the near zone than in the far zone (∝d {sup –1}). Hence the Solar signal may prove relevant for pulsar timing arrays. Other individual sources and the universal background fall well below the projected sensitivities of the Laser Interferometer Space Antenna and next-generation pulsar timing arrays. Stellar convection sets a fundamental noise floor for more sensitive stochastic gravitational-wave experiments in the more distant future.
79 ASTRONOMY AND ASTROPHYSICS↗
Tension in the void: cosmic rulers strain inhomogeneous cosmologies
New constraints on inhomogeneous Lemaitre-Tolman-Bondi (LTB) models alternative to Dark Energy are presented, focusing on adiabatic profiles with space-independent Big Bang and baryon fraction. The Baryon Acoustic Oscillation (BAO) scale at early times is computed in terms of the asymptotic value and then projected to different redshifts by following the geodesics of the background metric. Additionally, a model-independent method to constraint the local expansion rate using a prior on supernovae luminosity is presented. Cosmologies described by an adiabatic GBH matter profile with Ω{sub out} = 1 and Ω{sub out} ≤ 1 are investigated using a Markov Chain Monte Carlo analysis including the latest BAO data from the WiggleZ collaboration and the local expansion rate from the Hubble Space Telescope, together with Union2 type Ia supernovae data and the position and height of the Cosmic Microwave Background acoustic peaks. The addition of BAO data at higher redshifts increases considerably their constraining power and represents a new drawback for this type of models, yielding a value of the local density parameter Ω{sub in}∼>0.2 which is 3σ apart from the value Ω{sub in}∼<0.15 found using supernovae. The situation does not improve if the asymptotic flatness assumption is dropped, and a Bayesian analysis shows that constrained GBH models are ruled out at high confidence. We emphasize that these are purely geometric probes, that only recently have become sufficiently constraining to independently rule out the whole class of adiabatic LTB models.
79 ASTRONOMY AND ASTROPHYSICS↗
Confronting DGP braneworld gravity with cosmico observations after Planck data
The normal branch of Dvali-Gabadadze-Porrati braneworld gravity with brane tension is confronted by the currently available cosmic observations from the geometrical and dynamical perspectives. On the geometrical side, the type Ia supernova as standard candle, the baryon acoustic oscillation as standard ruler and the cosmic microwave background measurement from the first released 15.5 months data were used to fix the background evolutions. On the dynamical side, the redshift space distortion data will be used to determine the evolution of the matter perturbation. Through a Markov chain Monte Carlo analysis, we found the dimensionless crossover scale Ω{sub r{sub c}} = 1/(4H{sup 2}{sub 0}r{sup 2}{sub c}) = 0.00183{sub −0.00183}{sup +0.000338} in a spatially flat normal branch of Dvali-Gabadadze-Porrati braneworld. This result suggests that the crossover scale r{sub c} should be around 12H{sup −1}{sub 0} which is consistent with the previous result r{sub c} > 3H{sup −1}{sub 0} and greater. It also implies that the five-dimensional gravity effect is weak to be observed in H{sup −1}{sub 0} scale.
79 ASTRONOMY AND ASTROPHYSICS↗
Constraining cosmic curvature by using age of galaxies and gravitational lenses
We use two model-independent methods to constrain the curvature of the universe. In the first method, we study the evolution of the curvature parameter (Ω {sub k} {sup 0}) with redshift by using the observations of the Hubble parameter and transverse comoving distances obtained from the age of galaxies. Secondly, we also use an indirect method based on the mean image separation statistics of gravitationally lensed quasars. The basis of this methodology is that the average image separation of lensed images will show a positive, negative or zero correlation with the source redshift in a closed, open or flat universe respectively. In order to smoothen the datasets used in both the methods, we use a non-parametric method namely, Gaussian Process (GP). Finally from first method we obtain Ω {sub k} {sup 0} = 0.025±0.57 for a presumed flat universe while the cosmic curvature remains constant throughout the redshift region 0 < z < 1.37 which indicates that the universe may be homogeneous. Moreover, the combined result from both the methods suggests that the universe is marginally closed. However, a flat universe can be incorporated at 3σ level.
79 ASTRONOMY AND ASTROPHYSICS↗
Diagrammatic approach to nonlinear optical response with application to Weyl semimetals
Nonlinear optical responses are a crucial probe of physical systems including periodic solids. In the absence of electron-electron interactions, they are calculable with standard perturbation theory starting from the band structure of Bloch electrons, but the resulting formulas are often large and unwieldy, involving many energy denominators from intermediate states. This work gives a Feynman diagram approach to calculating nonlinear responses. This diagrammatic method is a systematic way to perform perturbation theory, which often offers shorter derivations and also provides a natural interpretation of nonlinear responses in terms of physical processes. Applying this method to second-order responses concisely reproduces formulas for the second-order-harmonic shift current. We then apply this method to third-order responses and derive formulas for third-order-harmonic generation and self-focusing of light, which can be directly applied to tight-binding models. Third-order responses in the semiclasscial regime include a Berry curvature quadrupole term, whose importance is discussed including symmetry considerations and when the Berry curvature quadrupole becomes the leading contribution. In conclusion, the method is applied to compute third-order optical responses for a model Weyl semimetal, where we find a new topological contribution that diverges in a clean material, as well as resonances with a peculiar linear character.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Nonuniform cosmological birefringence and active galactic nuclei
The CMB constrains the cosmological-birefringence rotation angle to be |{alpha}| < or approx. 1 deg. (1{sigma}) out to redshifts z{approx_equal}1100 for a rotation that is uniform across the sky. However, the rotation angle {alpha}({theta},{phi}) may vary with position ({theta},{phi}) on the sky, and if so, then it can be sought in current and future active galactic nuclei data. An upper limit <{alpha}{sup 2}>{sup 1/2} < or approx. 3.7 deg. to the scatter in the position-angle-polarization offsets in a sample of only N=9 active galactic nuclei already constrains the rotation spherical-harmonic coefficients to (4{pi}){sup -1/2{alpha}}{sub lm} < or approx. 3.7 deg. and constrains the power spectrum for {alpha} in models where it is a stochastic field. Future constraints can be improved with more sources and by analyzing well-mapped sources with a tensor-harmonic decomposition of the polarization.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
TiN Nanoporous Electrode Covered by Single Cell as Bio-Electronic Sensor of Radiation Hazard
Here we demonstrate a simple label-free bio-electronic radiation (ultra-violet) hazard detector based on non-destructive electrical impedance spectroscopy technique with a single living cell as a sensing element. Radiation results in wrong cell’s functioning and, as corollary, cell’s membrane distortion. The latter results in impedance shift for the electrode covered by the cell. The additional sensitivity of impedance shift is achieved by the simultaneous usage of the TiN porous electrodes and adaptive filtering for impedance data processing. The main advantage of the proposed sensor with respect to purely physical and/or chemical sensors is high selectivity: it a priory reacts only on the dangerous for living beings radiation.
36 MATERIALS SCIENCE↗
LiAISON (Life-cycle Assessment Integration into Scalable Open-source Numerical models) [SWR-24-01]
We introduce an open source prospective LCA framework, the Life-cycle Assessment Integration into Scalable Open-source Numerical models (LiAISON), to analyze the non-linear relationships between technology foreground and the future energy system background across a series of midpoint and resource use metrics The integration of LCA and IAM data is achieved using prospective environmental Impact assessment (PREMISE)7. We showcase it by assessing two Power-to-Hydrogen (PtH2) processes, namely Solid Oxide Electrolysis (SOE) and Polymer Electrolyte Membrane Electrolysis (PEME). We compare the technologies to a baseline of hydrogen production via natural gas-based Steam Methane Reforming (SMR) in a US context of multiple energy system and climate change mitigation futures. Besides providing an analysis that specifies the LCA results ranges with temporal and geospatial explicitness across the two technologies, metrics, and impact assessment methods, this research also aims to establish a base framework that can be expanded to use other IAM generated scenarios and US open-source life cycle inventory (LCI) databases. We find that the temporal environmental performance of either technology or their difference to SMR is directly influenced by the underlying background dynamics. Under baseline projections (i.e., no decarbonization goals), neither process reaches parity with the incumbent technology across several environmental metrics. Under the decarbonization scenarios, the underlying sectoral shifts result in declining impacts over time, compared to 2020 levels, except for metal depletion levels, which increase. The background shifts postulate a heavily decarbonized economy and energy system, which help technologies reach parity with SMR between 2040-2050 (RCP2.6) and 2030-2040 (RCP1.9) for global warming. Despite declines across several other metrics over time, neither PtH2 technology break even with SMR by 2100 besides for global warming. Scientific publication available here: https://pubs.acs.org/doi/full/10.1021/acs.est.2c04246
Ghosh, Tapajyoti↗
From Policy to Compliance: Federal Energy Efficient Product Procurement
Federal buyers are required to purchase energy-efficient products in an effort to minimize energy use in the federal sector, save the federal government money, and spur market development of efficient products. The Federal Energy Management Program (FEMP)’s Energy Efficient Product Procurement (EEPP) Program helps federal agencies comply with the requirement to purchase energy-efficient products by providing technical assistance and guidance and setting efficiency requirements for certain product categories. Past studies have estimated the savings potential of purchasing energy-efficient products at over $500 million per year in energy costs across federal agencies.1 Despite the strong policy support for EEPP and resources available, energy-efficient product purchasing operates within complex decision-making processes and operational structures; implementation challenges exist that may hinder agencies’ ability to comply with purchasing requirements. The shift to purchasing green products, including energy-efficient products, relies on “buy in” from a variety of potential actors throughout different purchasing pathways. Challenges may be especially high for EEPP relative to other sustainable acquisition programs given that efficient products frequently have a higher first cost than non-efficient ones, which may be perceived as a conflict with fiscal responsibility, or more simply problematic for agency personnel trying to stretch limited budgets. Federal buyers may also face challenges in determining whether a given product is subject to EEPP requirements. Previous analysis on agency compliance with EEPP, conducted by the Alliance to Save Energy (ASE), shows that federal agencies are getting better at purchasing energy-efficient products. ASE conducted two reviews of relevant solicitations for product and service contracts listed on Federal Business Opportunities (FBO), the centralized website where federal agencies are required to post procurements greater than $25,000. In 2010, ASE estimated a compliance rate of 46% in 2010, up from an estimate of 12% in 2008. Our work updates and expands on ASE’s 2010 analysis to gauge agency compliance with EEPP requirements.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗