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論文

Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

Goux, P.*; Glessgen, F.*; Gazzola, E.*; Singh Reen, M.*; Focillon, W.*; Gonin, M.*; 田中 智之*; 萩原 開人*; Ali, A.*; 須藤 高志*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2023(6), p.063H01_1 - 063H01_15, 2023/06

 被引用回数:0 パーセンタイル:0.01(Physics, Multidisciplinary)

We investigated the angular correlation of two $$gamma$$-rays emitted in neutron capture at the Materials and Life Science Experimental Facility of J-PARC. The 14 Ge crystals in a cluster detector and one coaxial Ge crystal were employed. We obtained angular correlation functions for two $$gamma$$-rays emerging in the electromagnetic transitions of the capture reactions on $$^{155}$$Gd and $$^{157}$$Gd. We found mild angular correlations for the strong, but rare transitions from the resonance state to two excited levels with known spin and parities. In contrast, angular correlations was negligibly small for arbitrary pairs of two $$gamma$$-rays produced in the majority of transitions in continuum states.

論文

Improved measurement of the $$0_2^+rightarrow0_1^+$$ $$E$$0 transition strength for $$^{72}$$Se using the SPICE spectrometer

Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.

Physical Review C, 106(1), p.014312_1 - 014312_9, 2022/07

 被引用回数:3 パーセンタイル:64.25(Physics, Nuclear)

The selenium isotopes lie at the heart of a tumultuous region of the nuclear chart where shape coexistence effects grapple with neutron-proton pairing correlations, triaxiality, and the impending proton dripline. In this work a study of $$^{72}$$Se by internal conversion electron and $$gamma$$-ray spectroscopy was undertaken with the SPICE and TIGRESS arrays. New measurements of the branching ratio and lifetime of the $$0_2^+$$ state were performed yielding a determination of $$rho^2(E0; 0_2^+{rightarrow}0_1^+)=29(3)$$ milliunits. Two state mixing calculations were performed that highlighted the importance of interpretation of such $$E0$$ strength values in the context of shape-coexistence.

論文

Expansion of agriculture in northern cold-climate regions; A Cross-sectoral perspective on opportunities and challenges

Unc, A.*; Altdorff, D.*; Abakumov, E.*; Adl, S.*; Baldursson, S.*; Bechtold, M.*; Cattani, D. J.*; Firbank, L. G.*; Grand, S.*; Gudjonsdottir, M.*; et al.

Frontiers in Sustainable Food Systems (Internet), 5, p.663448_1 - 663448_11, 2021/07

 被引用回数:34 パーセンタイル:94.15(Food Science & Technology)

本レビュー論文では、関連分野を研究する科学者の意識調査と既存文献の調査を実施し、地球温暖化の加速が寒冷な北方地域を地域および世界の農業セクター拡大にとってますます魅力的なターゲットにしていることを明らかにした。ただし、こうした活動の持続可能な長期的発展は、信頼性のある関連知見に対し全てのステークホルダーが容易にアクセスできる場合にのみ実現できる、という共通認識があることも明らかになった。特に、北方地域における農業の拡大は、温室効果ガス収支や生物多様性、生態系サービスに対し、負の影響をもたらす傾向にあることが明らかになってきている。以上より、寒冷な北方地域における農業の拡大と強化は、社会的な向上とニュートラルな環境影響とを両立できる計画の下で遂行される必要がある。

論文

Groundwater $$Elusimicrobia$$ are metabolically diverse compared to gut microbiome $$Elusimicrobia$$ and some have a novel nitrogenase paralog

M$'e$heust, R.*; Castelle, C. J.*; Matheus Carnevali, P. B.*; Farag, I. F.*; He, C.*; Chen, L.-X.*; 天野 由記; Hug, L. A.*; Banfield, J. F.*

ISME Journal, 14(12), p.2907 - 2922, 2020/12

 被引用回数:40 パーセンタイル:94.4(Ecology)

We reconstructed 94 draft-quality, non-redundant genomes from diverse animal-associated and natural environments. Genomes group into 12 clades, 10 of which previously lacked reference genomes. Groundwater-associated $$Elusimicrobia$$ are predicted to be capable of heterotrophic or autotrophic lifestyles, reliant on oxygen or nitrate/nitrite-dependent respiration of fatty acids, or a variety of organic compounds and Rnf-dependent acetogenesis with hydrogen and carbon dioxide as the substrates. Genomes from two clades of groundwater-associated $$Elusimicrobia$$ often encode a new homologous group of nitrogenase-like proteins that co-occur with an extensive suite of radical SAM-based proteins. We identified similar genomic loci in genomes of bacteria from the Gracilibacteria and Myxococcus phyla and predict that the gene clusters reduce a tetrapyrrole, possibly to form a novel cofactor. The animal-associated $$Elusimicrobia$$ clades nest phylogenetically within two groundwater-associated clades. Thus, we propose an evolutionary trajectory in which some $$Elusimicrobia$$ adapted to animal-associated lifestyles from groundwater-associated species via genome reduction.

論文

Population of a low-spin positive-parity band from high-spin intruder states in $$^{177}$$Au; The Two-state mixing effect

Venhart, M.*; Balogh, M.*; Herz$'a$$v{n}$, A.*; Wood, J. L.*; Ali, F. A.*; Joss, D. T.*; Andreyev, A. N.; Auranen, K.*; Carroll, R. J.*; Drummond, M. C.*; et al.

Physics Letters B, 806, p.135488_1 - 135488_6, 2020/07

 被引用回数:6 パーセンタイル:58.52(Astronomy & Astrophysics)

The extremely neutron-deficient isotopes $$^{177,179}$$Au were studied by means of in-beam $$gamma$$-ray spectroscopy. Specific tagging techniques, $$alpha$$-decay tagging in $$^{177}$$Au and isomer tagging in $$^{179}$$Au, were used for these studies. Feeding of positive-parity, nearly spherical states, which are associated with 2$$d_{3/2}$$ and 3$$s_{1/2}$$ proton-hole configurations, from the 1$$i_{13/2}$$ proton-intruder configuration was observed in $$^{177}$$Au. Such a decay path has no precedent in odd-Au isotopes and it is explained by the effect of mixing of wave functions of the initial state.

論文

Clades of huge phages from across Earth's ecosystems

Al-Shayeb, B.*; Sachdeva, R.*; Chen, L.-X.*; Ward, F.*; Munk, P.*; Devoto, A.*; Castelle, C. J.*; Olm, M. R.*; Bouma-Gregson, K.*; 天野 由記; et al.

Nature, 578(7795), p.425 - 431, 2020/02

 被引用回数:223 パーセンタイル:99.47(Multidisciplinary Sciences)

Phage typically have small genomes and depend on their bacterial hosts for replication. We generated metagenomic datasets from many diverse ecosystems and reconstructed hundreds of huge phage genomes, between 200 kbp and 716 kbp in length. Thirty four genomes were manually curated to completion, including the largest phage genomes yet reported. Expanded genetic repertoires include diverse and new CRISPR-Cas systems, tRNAs, tRNA synthetases, tRNA modification enzymes, initiation and elongation factors and ribosomal proteins. Phage CRISPR have the capacity to silence host transcription factors and translational genes, potentially as part of a larger interaction network that intercepts translation to redirect biosynthesis to phage-encoded functions. Some phage repurpose bacterial systems for phage-defense to eliminate competing phage. We phylogenetically define seven major clades of huge phage from human and other animal microbiomes, oceans, lakes, sediments, soils and the built environment. We conclude that large gene inventories reflect a conserved biological strategy, observed across a broad bacterial host range and resulting in the distribution of huge phage across Earth's ecosystems.

論文

$$alpha$$-decay properties of $$^{200,202}$$Fr

Ghys, L.*; Andreyev, A. N.; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; Cocolios, T. E.*; Cubiss, J.*; Derkx, X.*; et al.

Physical Review C, 100(5), p.054310_1 - 054310_13, 2019/11

 被引用回数:13 パーセンタイル:76.6(Physics, Nuclear)

The aim of this work was to investigate the $$alpha$$-decay properties of $$^{200,202}$$Fr and daughter products. Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Due to the very high statistics and the high beam purity, improved decay data for $$^{202}$$Fr and its daughters were obtained. The observation of crossover transitions positioned the isomeric high-spin level of $$^{198}$$At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of $$^{198}$$At and 52(3) ms for the ground-state decay of $$^{200}$$Fr.

論文

High-precision quadrupole moment reveals significant intruder component in $$^{33}_{13}$$Al$$_{20}$$ ground state

Heylen, H.*; De Rydt, M.*; Neyens, G.*; Bissell, M. L.*; Caceres, L.*; Chevrier, R.*; Daugas, J. M.*; 市川 雄一*; 石橋 陽子*; Kamalou, O.*; et al.

Physical Review C, 94(3), p.034312_1 - 034312_5, 2016/09

AA2016-0115.pdf:0.4MB

 被引用回数:38 パーセンタイル:91.71(Physics, Nuclear)

フランスGANIL研究所にて、中性子過剰核$$^{33}$$Alの電気的四重極モーメントの高精度測定を$$beta$$-NQR法を用いて行った。この領域の不安定核では、$$^{32}$$Mgでは中性子数20魔法数が消滅しており、$$^{34}$$Siでは中性子数20魔法数が保たれていることが知られている。その中間にある$$^{33}$$Alで魔法数が消滅しているか否かは大きな興味を持たれているが、これまでの実験では魔法数消滅の程度に対する決定的なデータは存在しなかった。この実験では、魔法数の消滅の程度に敏感と考えられている電気的四重極モーメントを高精度で測定し、$$|Q|=141(3)$$mbが得られた。この値を殻模型計算と比較したところ、$$^{33}$$Alでは魔法数が50%以上消滅していることが明らかになった。

論文

Single-photon emitting diode in silicon carbide

Lohrmann, A.*; 岩本 直也*; Bodrog, Z.*; Castelletto, S.*; 大島 武; Karle, T. J.*; Gali, A.*; Prawer, S.*; McCallum, J. C.*; Johnson, B. C.*

Nature Communications (Internet), 6, p.7783_1 - 7783_7, 2015/07

 被引用回数:145 パーセンタイル:96.84(Multidisciplinary Sciences)

A new single photon source (SPS) was found in hexagonal silicon carbide (SiC), and the luminescence from the SPS could be controlled by the operation of the pn diode. The SPS showed electro-luminescence (EL) with spectra between 700 and 850 nm (zero phonon line: 745 nm) and the EL could be easily observed at even room temperature (RT). Also, the SPS has very high thermal stability and can be observed even after 1800 $$^{circ}$$C annealing. The luminescence from the SPS was also observed by photo-luminescence measurements at RT. From Ab initio calculation, it was proposed that the silicon antisite defects beneath cubic SiC inclusion are a reasonable structure for the SPS although the identification of the SPS has not yet done.

論文

Coherent control of single spins in silicon carbide at room temperature

Widmann, M.*; Lee, S.-Y.*; Rendler, T.*; Son, N. T.*; Fedder, H.*; Paik, S.*; Yang, L.-P.*; Zhao, N.*; Yang, S.*; Booker, I.*; et al.

Nature Materials, 14(2), p.164 - 168, 2015/02

 被引用回数:438 パーセンタイル:99.56(Chemistry, Physical)

Single silicon vacancy (V$$_{Si}$$) in silicon carbide (SiC) was studied from the point of view of single photon source for quantum computing. The V$$_{Si}$$ centers were created in high purity semi-insulating hexagonal (4H)-SiC by 2 MeV electron irradiation with fluences up to 5$$times$$10$$^{15}$$ /cm$$^{2}$$. No subsequent annealing was carried out. A couple of solid immersion lens (SIL) with 20 $$mu$$m diameter were created on samples by ion milling using 40 keV Ga focused ion beam. A typical home-built confocal setup was used after optimizing for emission in the wavelength range around 900 nm. As a result, optically detected electron spin resonance (ODMR) for V$$_{Si}$$ was observed at room temperature (RT). Using ODMR, Rabi oscillations were also observed, and the Rabi frequency increased with increasing applied-magnetic field. In addition, spin relaxation time T$$_{1}$$ and T$$_{2}$$ were detected to be 500 $$mu$$s and 160 $$mu$$s, respectively.

論文

Room temperature quantum emission from cubic silicon carbide nanoparticles

Castelletto, S.*; Johnson, B. C.*; Zachreson, C.*; Beke, D.*; Balogh, I.*; 大島 武; Aharonovich, I.*; Gali, A.*

ACS Nano, 8(8), p.7938 - 7947, 2014/08

 被引用回数:86 パーセンタイル:90.39(Chemistry, Multidisciplinary)

Single Photon Sources (SPSs) in cubic (3C) Silicon Carbide (SiC) Nano Particles (NPs) were investigated. As a result, photo luminescence (PL) with broad emission at wavelength ranges between 600 and 800 nm was observed from 3C-SiC NPs at room temperature. The second order photon auto-correlation measurements revealed that defect with the PL characteristic is SPSs. The intensity and stability of the PL increased when samples were irradiated with electrons and subsequently annealed at 500 $$^{circ}$$C. From PL measurements at low temperature and theoretical analysis using spin-polarized density functional theory, the defect can be identified as carbon-antisite carbon-vacancy pair (C$$_{Si}$$V$$_{C}$$).

論文

Low-velocity transient-field technique with radioactive ion beams; $$g$$ factor of the first excited $$2^+$$ state in $$^{72}$$Zn

Illana, A.*; Jungclaus, A.*; Orlandi, R.; Perea, A.*; Bauer, C.*; Briz, J. A.*; Egido, J. L.*; Gernh$"a$user, R.*; Leske, J.*; M$"u$cher, D.*; et al.

Physical Review C, 89(5), p.054316_1 - 054316_11, 2014/05

 被引用回数:11 パーセンタイル:60.17(Physics, Nuclear)

The $$g$$ factor of the first excited state in $$^{72}$$Zn was measured using the transient-field technique in combination with Coulomb excitation. The experiment was ran at REX-ISOLDE, CERN, and the $$gamma$$-ray perturbed angular correlations were measured using 4 triple Germanium clusters of the Miniball array. The experimental result $$g$$(2$$_1^{+}$$) = +0.47(14) is significant to establish the structure of the Zn isotopes near N=40. Comparison with shell-model calculations reveal that to reproduce the measured energies and B(E2) of the Zn isotopes around N=40, both the proton excitations from the $$f_{7/2}$$ orbit and neutron excitations into the $$g_{9/2}$$ and $$d_{5/2}$$ orbits are essential. Furthermore, beyond-mean-field calculations reveal the need to include the triaxial degree of freedom.

論文

A Silicon carbide room-temperature single-photon source

Castelletto, S.*; Johnson, B.*; Ivady, V.*; Stavrias, N.*; 梅田 享英*; Gali, A.*; 大島 武

Nature Materials, 13(2), p.151 - 156, 2014/02

 被引用回数:413 パーセンタイル:99.43(Chemistry, Physical)

単一フォトンの発生や検出は量子力学の実験的な基盤や計測理論に重要な役割を示す。また、効率的、高品質の単一発光源は量子情報等の実現にとって不可欠と考えられている。本研究では、室温においても非常に明るく安定な炭化ケイ素(SiC)中の単一発光源の形成と同定に成功した。この単一発光源はSiC中のシリコンサイトを炭素で置換した炭素アンチサイト(C$$_{Si}$$)と炭素空孔(V$$_{C}$$)の複合欠陥(C$$_{Si}$$V$$_{C}$$)として知られる点欠陥であり、高純度SiCに対して、電子線照射と照射後の熱処理を組み合わせることで形成が可能となる。非常に明るい光源(2$$times$$10$$^{6}$$ counts/s)であり、キャビティーの使用が無い場合においても高い量子効率が得られる。

論文

Photoperiod-insensitive mutants with shorter plant height identified in the M1 generation of rice irradiated with carbon ion beams

Azad, M. A. K.*; Mazumdar, M. N. N.*; Chaki, A. K.*; Ali, M.*; Hakim, M. L.*; Mamun, A. N. K.*; 長谷 純宏; 野澤 樹; 田中 淳; 小池 亜紀*; et al.

SABRAO Journal of Breeding and Genetics, 45(2), p.179 - 186, 2013/06

短日植物であるイネは、短日条件に応答して出穂する。バングラデシュの在来品種Ashfalは、高い耐塩性及び冠水耐性を持つことから100年以上に渡って栽培されてきたが、光感受性が高いため、バングラデシュでの3つの作期のうち、長日条件にあたるboro期では出穂しないため栽培ができない。また、短日条件にあたるaman期においても草丈が高いために倒伏することがある。そこで、Ashfalへの炭素イオン照射によって光非感受性並びに矮性系統の作出を試みた。照射当代(M1)植物をboro期で栽培した結果、親品種のAshfalは全く出穂しなかったが、照射した計1,500粒の種子に由来する9個体が出穂した。このうち、草丈が低い3個体は稔性があり、次世代(M2)種子が得られた。これらの変異系統の形質を確認するため、M2種子をaman期で栽培した結果、Ashfalに比べて出穂が早いこと並びに草丈が低いことが確認され、また、遺伝的な分離は見られなかった。さらにM2植物から得たM3種子をboro期で栽培した結果、親品種のAshfalは全く出穂しなかったが、変異系統は出穂することが確認された。以上の結果から、炭素イオン照射によってM1世代で遺伝的に固定された光非感受性変異体が得られたことが示唆された。これらの変異系統は草丈も低いことから実用的価値も高いと考えられる。

論文

Measurement of the first ionization potential of astatine by laser ionization spectroscopy

Rothe, S.*; Andreyev, A. N.*; Antalic, S.*; Borschevsky, A.*; Capponi, L.*; Cocolios, T. E.*; De Witte, H.*; Eliav, E.*; Fedorov, D. V.*; Fedosseev, V. N.*; et al.

Nature Communications (Internet), 4, p.1835_1 - 1835_6, 2013/05

 被引用回数:84 パーセンタイル:94.4(Multidisciplinary Sciences)

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of smallest quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential (IP). Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states allowed the deduction of the IP of the astatine atom for the first time. New ab initio calculations were performed to support the experimental result. The measured value of IP(At) serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of super-heavy element 117, the heaviest homologue of astatine.

論文

Spins and magnetic moments of $$^{49}$$K and $$^{51}$$K; Establishing the 1/2$$^+$$ and 3/2$$^+$$ level ordering beyond $$N$$ = 28

Papuga, J.*; Bissell, M. L.*; Kreim, K.*; Blaum, K.*; Brown, B. A.*; De Rydt, M.*; Garcia Ruiz, R. F.*; Heylen, H.*; Kowalska, M.*; Neugart, R.*; et al.

Physical Review Letters, 110(17), p.172503_1 - 172503_5, 2013/04

 被引用回数:35 パーセンタイル:82.04(Physics, Multidisciplinary)

CERNのISOLDEにて、中性子過剰のカリウム同位体を生成,分離し、レーザー核分光によって$$^{49}$$K及び$$^{51}$$Kの基底状態のスピン及び磁気モーメントを初めて測定した。カリウム同位体は陽子数が19であるため、低励起状態に陽子の一空孔状態が観測されると考えられ、基底状態の量子数から陽子の殻構造の情報が引き出される。これまで、中性子数28の同位体までの基底状態が測定されており、中性子数20から28まで変化させると、基底状態が3/2$$^+$$から1/2$$^+$$へと変化するという準位の逆転現象が知られていた。今回の実験で、$$^{49}$$Kの基底状態は1/2$$^+$$, $$^{51}$$Kの基底状態は3/2$$^+$$であることが確定し、陽子準位が再逆転することを観測した。この再逆転現象は、標準的なポテンシャル模型では理解されず、殻模型計算によって、有効相互作用が殻構造の変化をもたらすのに本質的であることを明らかにした。

論文

Local thermal expansion and the C-C stretch vibration of the dicarbon antisite in 4H SiC

Devaty, R. P.*; Yan, F.*; Choyke, W. J.*; Gali, A.*; 木本 恒暢*; 大島 武

Materials Science Forum, 717-720, p.263 - 266, 2012/05

 被引用回数:1 パーセンタイル:54.53(Materials Science, Multidisciplinary)

The Carbon-Carbon (C-C) stretch vibration associated with the dicarbon antisite in 4H Silicon Carbide (SiC) has been observed from up to the fifth harmonic in the low temperature photoluminescence spectrum. By the fitting to the obtained data using the Morse potential, we can obtain the reasonable anharmonicity. We also combined experimental results, the analytically tractable Morse potential, and results obtained from first principles calculations in order to estimate the thermal expansion coefficient of the C-C bond. This local thermal expansion coefficient is considerably smaller than the linear thermal expansion coefficient of bulk 4H SiC, in striking contrast with the recent result obtained from the nitrogen-vacancy center in diamond that the local thermal expansion coefficientis larger than the bulk value.

論文

Anharmonic vibrations of the dicarbon antisite defect in 4H-SiC

Yan, F.*; Devaty, R. P.*; Choyke, W. J.*; Gali, A.*; 木本 恒暢*; 大島 武; Pensl, G.*

Applied Physics Letters, 100(13), p.132107_1 - 132107_3, 2012/03

 被引用回数:3 パーセンタイル:13.48(Physics, Applied)

Dicarbon antisite defects were introduced into 4H Silicon Carbide (SiC) by either electron irradiation or ion implantation (H or He) and subsequent annealing between 700 and 1700 $$^{circ}$$C for 30 min in Ar. As a result of low temperature photoluminescence at 2 K, the no-phonon lines from the dicarbon antisite defect center were detected with their phonon replicas. The stretch frequencies of the defect with up to the fifth harmonic were also observed. The Morse potential model accounts for the anharmonicity quite well and gives a very good prediction of the vibration energies up to the fifth harmonic at an error within 1%. The observed anharmonicity can be explained in terms of the model of a dicarbon antisite defect along with its four nearest neighboring carbon atoms using first principles calculations.

論文

Defects at nitrogen site in electron-irradiated AlN

Son, N. T.*; Gali, A.*; Szab$'o$, $'A$.*; Bikermann, M.*; 大島 武; 磯谷 順一*; Janz$'e$n, E.*

Applied Physics Letters, 98(24), p.242116_1 - 242116_3, 2011/06

 被引用回数:9 パーセンタイル:37.91(Physics, Applied)

耐放射線性にも優れるといわれる窒化アルミ(AlN)中に発生する照射欠陥に関しての知見を得るために、AlN試料に2MeV電子線を照射し、発生した欠陥を電子常磁性共鳴(EPR)により調べた。その結果、EI-1と名付けられたスピン1/2の欠陥中心が観測された。電子のスピンと囲まれる4つの$$^{27}$$Aの核スピンとの超微細相互作用を詳細に調べ、さらに、スーパーセルを用いた理論計算結果と比較したところ、得られたEI-1中心はAlN中の中性の窒素空孔型の欠陥であると帰結できた。

論文

EPR and ${it ab initio}$ calculation study on the EI4 center in 4$$H$$- and 6$$H$$-SiC

Carlsson, P.*; Son, N. T.*; Gali, A.*; 磯谷 順一*; 森下 憲雄; 大島 武; Magnusson, B.*; Janz$'e$n, E.*

Physical Review B, 82(23), p.235203_1 - 235203_11, 2010/12

 被引用回数:11 パーセンタイル:46(Materials Science, Multidisciplinary)

六方晶(4$$H$$及び6$$H$$)炭化ケイ素(SiC)中のEI4欠陥中心に関して電子常磁性共鳴(EPR)による評価を行った。高純度半絶縁性のSiCに電子線照射を行い、その後700$$sim$$750$$^{circ}$$Cの熱処理を行うことでEI4欠陥中心が増加することが判明した。$$^{29}$$Si及び$$^{13}$$Cの超微細相互作用を調べ、熱処理によるEPRシグナルの変化量及び異なる炭素空孔型欠陥を考慮した${it ab initio}$ supercell計算の結果、このEI4センターが中性の炭素空孔とシリコンサイトに炭素が入ったアンチサイトと炭素空孔の複合欠陥((V$$_{C}$$-C$$_{Si}$$V$$_{C}$$)$$^{0}$$)であることが同定できた。

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