13 research outputs found
Kinetic and Diagnostic Studies of Molecular Plasmas Using Laser Absorption Techniques
Within the last decade, mid-infrared absorption spectroscopy between 3 and 20 ÎŒm â known as infrared laser absorption spectroscopy (IRLAS) and based on tunable semiconductor lasers, namely lead salt diode lasers, often called tunable diode lasers (TDLs), and quantum cascade lasers (QCLs) â has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry of molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, and organosilicon compounds has led to further applications of IRLAS because most of these compounds and their decomposition products are infrared active. IRLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetics. Information about gas temperature and population densities can also be derived from IRLAS measurements. A variety of free radicals and molecular ions have been detected, especially using TDLs. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of QCLs offers an attractive new option for the monitoring and control of industrial plasma processes as well as for highly time-resolved studies on the kinetics of plasma processes. The aim of the present contribution is threefold (1) to review recent achievements in our understanding of molecular phenomena in plasmas including interactions with solid surfaces, (2) to report on selected studies of the spectroscopic properties and kinetic behavior of radicals, and (3) to review new applications of QCLs and to describe the current status of advanced instrumentation for QCLAS in the midinfrared.</p
Determination of atmospherically deposited microplastics in moss: Method development and performance evaluation
The investigation of atmospheric microplastic pollution is a rising topic within microplastic research. However, sampling strategies concerning atmospheric microplastics are not standardized yet and strongly depend on the scientific objectives investigated. A few research groups are currently focused on determining atmospherically deposited microplastics in moss, as it can be a biomonitoring system for other atmospheric pollutants such as heavy metals, nitrogen, and persistent organic components. In this context, and for atmospheric microplastics in general, almost all examinations focus on determining microplastic numbers and shapes, while polymer masses are barely investigated. However, particle- and mass-based information are needed to assess the fate of atmospherically transported microplastics in the environment. For this purpose, this study shows the development and evaluation of a new sample preparation method for determining microplastics in moss for both analytical approaches using thermal extraction desorption-gas chromatography-mass spectrometry (TED-GC-MS) and Raman microspectroscopy (”Raman). Further, this newly developed microplastics/moss separation method (”PEEL) was compared to oxidative digestion using Fenton's reagent, usually used as a sample preparation method for organic-rich samples and moss. The method comparison was performed concerning green analytical chemistry (GAC) and its respective method functionality. The greenness was assessed using the software tool AGREEprep, which covers ten comprehensive aspects of GAC. Both methodsâ functionality was assessed regarding observable matrix interferences and the data quality achieved. It is demonstrated that ”PEEL benefits GAC and method functionality since harmful chemicals can be avoided, matrix interferences can be minimized, and the separation quality is increased
Reduction of silicon dioxide interfacial layer to 4.6 A EOT by Al remote scavenging in high K/metal gate stacks on Si
The continued device scaling demands the reduction of the equivalent oxide thickness (EOT) below 1 nm. For HfO2-based gate stacks, the interfacial SiO2 limits the EOT scaling. A low EOT can only be achieved if the interfacial layer (IL) is reduced to its physical limit of âŒ4 Ă
. Such thin EOT are achievable if redox reactions within the gate stack are employed in order to reduce SiO2. This study reports on the use of an Al layer in combination with a TiN metal electrode to reduce the IL and achieve lowest EOT values. The lowest EOT achieved was 4.6 Ă
. However, the scavenging process was found to strongly depend on the thermal budget after Al deposition. The presented process adapts a standard metal-inserted poly-Si flow (MIPS) prior to Al deposition, but may also be an option to control IL regrowth
Global sea-level budget 1993-present
Abstract. Global mean sea level is an integral of changes occurring in the climate system in response to unforced climate variability as well as natural and anthropogenic forcing factors. Its temporal evolution allows changes (e.g., acceleration) to be detected in one or more components. Study of the sea-level budget provides constraints on missing or poorly known contributions, such as the unsurveyed deep ocean or the still uncertain land water component. In the context of the World Climate Research Programme Grand Challenge entitled Regional Sea Level and Coastal Impacts, an international effort involving the sea-level community worldwide has been recently initiated with the objective of assessing the various datasets used to estimate components of the sea-level budget during the altimetry era (1993 to present). These datasets are based on the combination of a broad range of space-based and in situ observations, model estimates, and algorithms. Evaluating their quality, quantifying uncertainties and identifying sources of discrepancies between component estimates is extremely useful for various applications in climate research. This effort involves several tens of scientists from about 50 research teams/institutions worldwide (www.wcrp-climate.org/grand-challenges/gc-sea-level, last access: 22 August 2018). The results presented in this paper are a synthesis of the first assessment performed during 2017â2018. We present estimates of the altimetry-based global mean sea level (average rate of 3.1â±â0.3âmmâyrâ1 and acceleration of 0.1âmmâyrâ2 over 1993âpresent), as well as of the different components of the sea-level budget (http://doi.org/10.17882/54854, last access: 22 August 2018). We further examine closure of the sea-level budget, comparing the observed global mean sea level with the sum of components. Ocean thermal expansion, glaciers, Greenland and Antarctica contribute 42â%, 21â%, 15â% and 8â% to the global mean sea level over the 1993âpresent period. We also study the sea-level budget over 2005âpresent, using GRACE-based ocean mass estimates instead of the sum of individual mass components. Our results demonstrate that the global mean sea level can be closed to within 0.3âmmâyrâ1 (1Ï). Substantial uncertainty remains for the land water storage component, as shown when examining individual mass contributions to sea level.
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Competition and moral behavior: a meta-analysis of forty-five crowd-sourced experimental designs
Does competition affect moral behavior? This fundamental question has been debated among leading scholars for centuries, and more recently, it has been tested in experimental studies yielding a body of rather inconclusive empirical evidence. A potential source of ambivalent empirical results on the same hypothesis is design heterogeneity-variation in true effect sizes across various reasonable experimental research protocols. To provide further evidence on whether competition affects moral behavior and to examine whether the generalizability of a single experimental study is jeopardized by design heterogeneity, we invited independent research teams to contribute experimental designs to a crowd-sourced project. In a large-scale online data collection, 18,123 experimental participants were randomly allocated to 45 randomly selected experimental designs out of 95 submitted designs. We find a small adverse effect of competition on moral behavior in a meta-analysis of the pooled data. The crowd-sourced design of our study allows for a clean identification and estimation of the variation in effect sizes above and beyond what could be expected due to sampling variance. We find substantial design heterogeneity-estimated to be about 1.6 times as large as the average standard error of effect size estimates of the 45 research designs-indicating that the informativeness and generalizability of results based on a single experimental design are limited. Drawing strong conclusions about the underlying hypotheses in the presence of substantive design heterogeneity requires moving toward much larger data collections on various experimental designs testing the same hypothesis.For financial support, we thank the Austrian National Bank (grant 17788 to M. Kirchler), Austrian Science Fund (grants SFB F6307 to A.D.; SFB F6309 to J.H.; and SFB F6310 to M. Kirchler), Jan Wallander and Tom Hedelius Foundation (grant P21-0091 to A.D.), Knut and Alice Wallenberg Foundation (grant KAW 2018.0134 to A.D.), Marianne and Marcus Wallenberg Foundation (grant KAW 2019.0434; to A.D.), Radboud University Nijmegen (grant 2701437 to U.W.), and Riksbankens Jubileumsfond (grant P21-0168 to M. Johannesson)