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[en] Graphical abstract: -- Highlights: •Theory and analytical considerations for molecular absorption spectrometry (MAS). •Critical review of low resolution MAS. •Critical review of the analytical performance of high-resolution continuum source (HR-CS) flame MAS. •Critical review of the analytical performance of HR-CS graphite furnace MAS. •Current status of HR-CS MAS and its future prospects for elemental analysis. -- Abstract: Molecular absorption spectrometry (MAS), originally developed in the 1970s, is a technique to determine non-metals in flames and graphite furnaces by monitoring the absorbance of diatomic molecules. Early studies employed low resolution instruments designed for line source atomic absorption, which provided a limited choice of analytical wavelengths, insufficient spectral resolution, and spectral interferences. However, the development of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) instrumentation has allowed the analysis of challenging samples for non-metals as well as some difficult elements to determine by AAS, such as aluminum and phosphorus. In this review, theory and analytical considerations for MAS are discussed. The principles and limitations of low resolution MAS are described, along with its applications. HR-CS AAS instrumentation is reviewed, emphasizing performance characteristics most relevant for MAS. Applications of flame and HR-CS GFMAS are reviewed, highlighting the most significant work to date. The paper concludes with an evaluation of the enhanced analytical capabilities provided by HR-CS MAS
[en] Aromatic and oxygenated compounds emitted in automobile exhaust are of concern because of their toxicity, ability to undergo photochemical reactions in air to produce ozone, and persistence in ground water. Current analytical protocols for these compounds involve chromatographic methods that preclude real-time measurements. Laser mass spectrometry methods using direct sampling interfaces provide a sensitive, selective alternative to these procedures that allows real-time analysis. Two major approaches have been developed. Resonance enhanced ionization mass spectrometry (REMPI) time-of-flight mass spectrometry (TOFMS) involves the use of a tunable laser to selectively ionize molecules. Single photon ionization (SPI) ion trap mass spectrometry (ITMS) employs vacuum ultraviolet light to selectively ionize the analytes while discriminating against the major components of air. In this paper, the instrumentation and results obtained with these two instrumental approaches are discussed. The conclusion of the article is a comparison of proposed roles these instruments for exhaust analysis.
[en] We formulate macroscopic quantum electrodynamics in the most general linear, absorbing media. In particular, Onsager reciprocity is not assumed to hold. The field quantization is based on the source-quantity representation of the electromagnetic field in terms of the dyadic Green's tensor. For media with a nonlocal response, a description in terms of a complex conductivity tensor is employed. As an alternative description, we introduce the permittivity, permeability and magnetoelectric susceptibilities to obtain an explicitly duality-invariant scheme. We find that duality invariance only holds as a continuous symmetry when nonreciprocal responses are allowed for. (paper)
[en] The chiral component of the Casimir–Polder potential is derived within the framework of macroscopic quantum electrodynamics. It is shown to exist only if the particle and the medium are both chiral. Furthermore, the chiral component of the Casimir–Polder potential can be attractive or repulsive, depending on the chirality of the molecule and the medium. The theory is applied to a cavity geometry in the non-retarded limit with the intention of enantiomer separation. For a ground state molecule the chiral component is dominated by the electric component and thus no explicit separation will happen. If the molecule is initially in an excited state the electric component of the Casimir–Polder force can be suppressed by an appropriate choice of material and the chiral component can select the molecule based on its chirality, allowing enantiomeric separation to occur. (paper)
[en] The 21. annual World Energy Markets Observatory (WEMO) reveals a world struggling to balance the desire for continued economic growth with the need to take deliberate and drastic steps against climate change. In 2018, global energy consumption rose 2.3 percent - nearly twice the average rate since 2010 - as driven by a robust worldwide economy. Despite the rapid growth of renewables in some regions, oil, gas and coal accounted for nearly three-quarters of the increase in total energy demand, their highest share in five years. As a result, greenhouse gas emissions climbed 2 percent globally, a significant break from the plateau of 2014 to 2016. While renewables remain the fastest-growing energy source worldwide, investments during the first half of 2019 declined 14 percent compared with the same period in 2018. Population growth, as well as a lack of anticipated technical breakthroughs over the next two decades, further contribute to a bleak medium- and long-term landscape. This year's WEMO report explores these issues in greater detail and presents new ideas for how utilities, policy-makers and private companies can embrace a long-term strategy that balances growth and change - and draws opportunity from crisis.
[en] The World Energy Council's definition of energy sustainability is based on three core dimensions: Energy Security, Energy Equity, and Environmental Sustainability of Energy Systems. Balancing these three goals constitutes a 'Trilemma' and balanced systems enable prosperity and competitiveness of individual countries. The World Energy Trilemma Index presents a comparative ranking of 128 countries' energy systems. It provides an assessment of a country's energy system performance, reflecting balance and robustness in the three Trilemma dimensions. To provide greater insight, we have evolved the methodology for the 2019 Trilemma and, for the first time, introduced visualisation of historical trends to enable the Trilemma performance of individual countries to be tracked back two decades to 2000. The new time-series analysis provides insights into a country's historical trends, challenges and opportunities for improvements in meeting energy goals now and in the future. The Index demonstrates the impact of varying policy pathways countries have taken in each of the dimensions over the past 20 years. Looking at these trends can inform a dialogue on national energy policy to promote coherence and integration to enable better calibrated energy systems in the context of the global energy transition challenge. Ten countries achieve the top AAA balance grade in the 2019 World Energy Trilemma Index, representing top quartile performance in every dimension. Since 2000, no countries have consistently improved in each dimension every year; instead most show historical trends with a variety of peaks and troughs in a general upward direction. Overall Trilemma performance for 119 countries over the 20-year period has improved, with only 9 countries seeing their overall performance declining. The rate of improvement in overall Trilemma performance also increases as the transition progresses and encourages countries to improve their energy policies. The overall top three countries across all three Trilemma dimensions are Switzerland, Sweden and Denmark. For the Energy Security dimension, the top performing countries in 2019 are Sweden, Denmark, and Finland. The top of the Energy Equity dimension traditionally ranks well-endowed or well-connected countries and geographically concentrated populations with access to abundant and affordable energy: Luxembourg, Bahrain and Qatar are the top performers in 2019. The leaders of the 2019 ranking for the Environmental Sustainability of Energy Systems are countries making steady gains on the pathway to decarbonization and pollution control, in the context of sustainable economic growth. The top performers in this dimension are also the overall Trilemma leaders - Switzerland, Denmark and Sweden. Across the different regions of the world, pathways through the transition are different, and leading countries in each region represent this diversity. The top 10 2019 Trilemma ranking is dominated by European countries, with Switzerland as the top performer in Europe both due to robust baseline systems and coherent policies improving upon these. Uruguay ranks highest of all Latin American and Caribbean countries, with high scores in the Security and Sustainability dimensions. In the Middle East and Gulf region, Israel ranks highest due to its performance in Sustainability compared to the regional average. New Zealand, with a placing in the global top 10, heads up the Asia-Pacific region with an AAA grade. Mauritius is ahead of other countries in Africa, balancing both Equity and Sustainability performance. Canada represents the best overall performance in the North American region due to strong Energy Security and a commitment to balanced and integrated energy policy