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Tilmann E Kuhn - One of the best experts on this subject based on the ideXlab platform.
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calorimetric determination of the solar heat Gain coefficient G with steady state laboratory measurements
Energy and Buildings, 2014Co-Authors: Tilmann E KuhnAbstract:Abstract The paper describes procedures for the direct calorimetric measurement of the solar heat Gain coefficient G in detail. G is also called SHGC, solar factor, G-Value or total solar enerGy transmittance TSET. All these terms are used synonymously in this document althouGh there are some differences in the details of the definitions of these properties (e.G. different reference wind conditions or reference solar spectra). The document aims to summarize more than 25 years of experience in G-Value testinG at Fraunhofer ISE, FreiburG, Germany, which includes many different transparent and translucent buildinG materials ranGinG from transparent insulation materials to dayliGhtinG and solar control systems and active solar enerGy harvestinG facade components like buildinG-inteGrated PV systems (BIPV) or buildinG-inteGrated solar thermal collectors (BIST). The document focuses on methods for the calorimetric measurement of G under steady-state laboratory conditions. Transient outdoor measurements are beyond the scope of this paper. It also describes the correspondinG error analysis and methods to correct experimentally determined Values Gexp to reference conditions, if it is not possible to reproduce the reference boundary conditions exactly in the laboratory.
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calorimetric determination of the solar heat Gain coefficient G with steady state laboratory measurements
Energy and Buildings, 2014Co-Authors: Tilmann E KuhnAbstract:Abstract The paper describes procedures for the direct calorimetric measurement of the solar heat Gain coefficient G in detail. G is also called SHGC, solar factor, G-Value or total solar enerGy transmittance TSET. All these terms are used synonymously in this document althouGh there are some differences in the details of the definitions of these properties (e.G. different reference wind conditions or reference solar spectra). The document aims to summarize more than 25 years of experience in G-Value testinG at Fraunhofer ISE, FreiburG, Germany, which includes many different transparent and translucent buildinG materials ranGinG from transparent insulation materials to dayliGhtinG and solar control systems and active solar enerGy harvestinG facade components like buildinG-inteGrated PV systems (BIPV) or buildinG-inteGrated solar thermal collectors (BIST). The document focuses on methods for the calorimetric measurement of G under steady-state laboratory conditions. Transient outdoor measurements are beyond the scope of this paper. It also describes the correspondinG error analysis and methods to correct experimentally determined Values Gexp to reference conditions, if it is not possible to reproduce the reference boundary conditions exactly in the laboratory.
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variable G Value of transparent facade collectors
Energy and Buildings, 2012Co-Authors: Christoph Maurer, Tilmann E KuhnAbstract:Transparent solar thermal collectors (TSTC) represent a new development. An adequate model is needed to predict their performance. This paper presents a collector model with an advanced calculation of the transmission of diffuse radiation and a connection to the buildinG which allows analysis of the collector Gains and of the G Value, also called “solar factor”, “solar heat Gain coefficient (SHGC)” or “total solar enerGy transmittance”. The model is implemented as a TRNSYS Type and a coupled simulation between a collector and a room is presented for different facade constructions. Facade areas with GlazinG and venetian blinds are simulated with a second new TRNSYS Type which introduces hiGh modellinG accuracy for facades with solar control systems. An HVAC system is presented toGether with a first estimate of possible reductions of primary enerGy. It indicates primary enerGy savinGs of about 30% by replacinG opaque walls with transparent collectors. The G Values prove to depend not only on the irradiation, but also on the operation of the solar collectors and vary e.G. between 0.04 and 0.21. Detailed modellinG of active facades like TSTC is therefore essential for accurate predictions of the collector Gain, the heatinG and coolinG loads and the thermal comfort.
Michael A Mcguire - One of the best experts on this subject based on the ideXlab platform.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
Applied Physics Letters, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), the linewidth increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism, and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn–Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
arXiv: Materials Science, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), line width increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn-Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
Oleg G Poluektov - One of the best experts on this subject based on the ideXlab platform.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
Applied Physics Letters, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), the linewidth increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism, and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn–Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
arXiv: Materials Science, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), line width increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn-Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
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electronic structure of the p700 special pair from hiGh frequency electron paramaGnetic resonance spectroscopy
Journal of Physical Chemistry B, 2002Co-Authors: Oleg G Poluektov, Gary W. Brudvig, Lisa M Utschig, Sandra L Schlesselman, K V Lakshmi, And Gerd Kothe, Marion C ThurnauerAbstract:Enhanced spectral resolution of hiGh-frequency electron paramaGnetic resonance (EPR) spectroscopy allows for detailed G-tensor analysis of the active paramaGnetic piGments in photosynthetic reaction centers. This analysis has been made for the cation radical and triplet state of the primary donor in photosystem I (P700) compared to the same species from chlorophyll a (Chla) in vitro. The data prove that the electronic structures of the primary donor cation and triplet state are very different from those of monomeric Chla. The G-Value anisotropy of P700+• is smaller, and the Gz component considerably deviates from that of Chla+•. The triplet state of P700 is also different from ChlaT. In the present study, this difference is resolved because of the hiGh G-Value resolution of the hiGh-frequency EPR and characterized by the switchinG of the directions of the X and Y G-tensor axes with respect to the zero-field axes. These results can be explained either by a delocalized electronic character of the P700+• and...
S R Singamaneni - One of the best experts on this subject based on the ideXlab platform.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
Applied Physics Letters, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), the linewidth increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism, and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn–Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
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liGht induced electron spin resonance properties of van der waals crx3 x cl i crystals
arXiv: Materials Science, 2020Co-Authors: S R Singamaneni, Oleg G Poluektov, L M Martinez, Jens Niklas, Ravi Yadav, Michele Pizzochero, Oleg V Yazyev, Michael A McguireAbstract:The research on layered van der Waals (vdW) maGnets is rapidly proGressinG owinG to excitinG fundamental science and potential applications. In bulk crystal form, CrCl3 is a vdW antiferromaGnet with in-plane ferromaGnetic orderinG below 17 K, and CrI3 is a vdW ferromaGnet below 61 K. Here, we report on the electron spin resonance (ESR) properties of CrCl3 and CrI3 sinGle crystals upon photo-excitation in the visible ranGe. We noticed remarkable chanGes in the ESR spectra upon illumination. In the case of CrCl3, at 10 K, the ESR siGnal is shifted from G = 1.492 (dark) to 1.661 (liGht), line width increased from 376 to 506 Oe, and the siGnal intensity is reduced by 1.5 times. Most interestinGly, the observed chanGe in the siGnal intensity is reversible when the liGht is cycled on/off. We observed almost no chanGe in the ESR spectral parameters in the paramaGnetic phase (>20 K) upon illumination. Upon photo-excitation of CrI3, the ESR siGnal intensity is reduced by 1.9 times; the G-Value increased from 1.956 to 1.990; the linewidth increased from 1170 to 1260 Oe at 60 K. These findinGs are discussed by takinG into account the skin depth, the slow relaxation mechanism and the appearance of low-symmetry fields at the photo-Generated Cr2+ Jahn-Teller centers. Such an increase in the G-Value as a result of photo-Generated Cr2+ ions is further supported by our many-body wavefunction calculations. This work has the potential to extend to monolayer vdWs maGnets by combininG ESR spectroscopy with optical excitation and detection.
Makoto Sekine - One of the best experts on this subject based on the ideXlab platform.
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real time in situ electron spin resonance measurements on funGal spores of penicillium diGitatum durinG exposure of oxyGen plasmas
Applied Physics Letters, 2012Co-Authors: Kenji Ishikawa, Hiroshi Hashizume, Hiroko Mizuno, Kazuhiro Tamiya, Sachiko Iseki, Hiromasa Tanaka, Keigo Takeda, Hiroki Kondo, Takayuki Ohta, Makoto SekineAbstract:We report the kinetic analysis of free radicals on funGal spores of Penicillium diGitatum interacted with atomic oxyGen Generated plasma electric discharGe usinG real time in situ electron spin resonance (ESR) measurements. We have obtained information that the ESR siGnal from the spores was observed and preliminarily assiGnable to semiquinone radical with a G-Value of around 2.004 and a line width of approximately 5G. The decay of the siGnal is possibly linked to the inactivation of the funGal spore. The real-time in situ ESR has proven to be a useful method to elucidate plasma-induced surface reactions on bioloGical specimens.
