中国科学院机构知识库网格系统: 检索

Raman spectroscopic and X-ray diffraction study of alpha- and beta-Mg2P2O7 at various temperatures 期刊论文 OAI收割
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2022, 卷号: 273, 页码: 121076
作者: Weihong Xue; Kuan Zhai; Hu Wang; Xiang Wu; Wen Wen

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收藏 | 浏览/下载：14/0 | 提交时间：2023/03/22

Mg2p2o7 phase Transition raman Spectra x-ray Diffraction high Temperature

A combined experiment and first-principles study on lattice dynamics of thermoelectric CuInTe2 期刊论文 OAI收割
JOURNAL OF ALLOYS AND COMPOUNDS, 2020, 卷号: 822
作者: Yu, Hao; Huang, Ge; Peng, Qing; Chen, Liu-Cheng; Pang, Hong-Jie

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收藏 | 浏览/下载：38/0 | 提交时间：2020/11/26

Chalcopyrite compounds X-ray diffraction Raman spectra Ab initio calculations

Kinetics, compositions and structures of carbon dioxide/hydrogen hydrate formation in the presence of cyclopentane 期刊论文 OAI收割
APPLIED ENERGY, 2020, 卷号: 265, 页码: 9
作者: Yu, Yi-Song; Zhang, Qing-Zong; Li, Xiao-Sen; Chen, Chang; Zhou, Shi-Dong

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收藏 | 浏览/下载：23/0 | 提交时间：2020/10/29

Cyclopentane Hydrate CO2 recovery Raman spectra X-ray Gas-liquid ratio

Probing NaCl hydrate formation from aqueous solutions by terahertz time-domain spectroscopy 期刊论文 OAI收割
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2020, 卷号: 22, 期号: 32, 页码: 17791-17797
作者: Chen, LG; Ren, GH; Liu, LY; Guo, P; Wang, ED

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收藏 | 浏览/下载：38/0 | 提交时间：2021/09/06

X-RAY MOLECULAR-DYNAMICS WATER-STRUCTURE THZ SPECTRA ICE IONS HYSTERESIS PRINCIPLES SCATTERING PHASE

No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文 OAI收割
Nature, 2020, 卷号: 587, 页码: 63-65
作者: HXMT

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收藏 | 浏览/下载：44/0 | 提交时间：2022/02/08

Astrophysics - High Energy Astrophysical Phenomena Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文 OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者: HXMT

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收藏 | 浏览/下载：49/0 | 提交时间：2022/02/08

Insight-HXMT Geant4 simulation Background observation Astrophysics - Instrumentation and Methods for Astrophysics Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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收藏 | 浏览/下载：58/0 | 提交时间：2022/02/08

accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Lattice dynamics of thermoelectric palladium sulfide 期刊论文 OAI收割
JOURNAL OF ALLOYS AND COMPOUNDS, 2019, 卷号: 798, 页码: 484
作者: Chen, Liu-Cheng; Peng, Qing; Yu, Hao; Pang, Hong-Jie; Jiang, Bin-Bin

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收藏 | 浏览/下载：66/0 | 提交时间：2019/12/26

Palladium sulfide X-ray diffraction Raman spectra Ab initio calculations

Finely Tuned Structure and Catalytic Performance of Cerium Oxides by a Continuous Samarium Doping from 0 to 100% 期刊论文 OAI收割
INORGANIC CHEMISTRY, 2019, 卷号: 58, 期号: 19, 页码: 13066-13076
作者: Tao, R; Xu, JS; Zhong, H; Wen, W; Pan, QF

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收藏 | 浏览/下载：24/0 | 提交时间：2020/10/16

GD-DOPED CERIA X-RAY-DIFFRACTION ALCOHOL ELECTROOXIDATION RAMAN-SPECTRA CEO2 NANOPARTICLES EVOLUTION DEFECTS STABILITY ARRAYS

High-pressure in-situ X-ray diffraction and Raman spectroscopy of Ca 2 AlFeO 5 brownmillerite 期刊论文 OAI收割
High Pressure Research, 2019, 卷号: 39, 期号: 1, 页码: 92-105
作者: Zeming Li; Yuan Yin; Justin D. Rumney; Sean R. Shieh; Jingui Xu; Dawei Fan; Wen Liang; Shuai Yan; Shuangmeng Zhai

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收藏 | 浏览/下载：22/0 | 提交时间：2020/12/08

Brownmillerite Ca2alfeo5 High-pressure X-ray Diffraction Raman Spectra