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Your search keyword '"Wei, Mingzhi"' showing total 282 results
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282 results on '"Wei, Mingzhi"'

24. Isomerization of surface functionalized SWCNTs and the critical influence on photoluminescence: static calculations and excited-state dynamics simulations.

Author

Chen, Shunwei, Li, Yi, Chen, Xinxin, Li, Lingyun, Lu, Qifang, Guo, Enyan, Si, Conghui, Wei, Mingzhi, and Han, Xiujun

Abstract

Single-walled carbon nanotubes (SWCNTs) functionalized with sparse surface chemical groups are promising for a variety of optical applications such as quantum information and bio-imaging. However, the luminescence efficiencies and stability, two key aspects, undoubtedly govern their practical usage. Herein, we assess the surface migration of oxygen and triazine groups on as-modified SWCNT fragments by adopting transition state theory and explore the de-excitation of oxygen-functionalized SWCNT fragments by performing non-adiabatic excited-state dynamics simulations. According to the predicted moderate or even small reaction barriers, the migration of both oxygen and triazine groups is feasible from an sp3 defect configuration forming an energetically more stable sp2 configuration at moderate or even room temperatures. Such isomerization leads to drastically different light emission capabilities as indicated by the large or zero oscillator strengths. During the dynamics simulations, the lowest excited singlet (S1) state rapidly decays in energy within 20 fs and then fluctuates until the end, providing insights into the emission mechanism of SWCNTs. This study highlights the potential intrinsic limitations of surface-functionalized SWCNTs for luminescence applications. [ABSTRACT FROM AUTHOR]

Published
2024
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32. APF - The Lick Observatory Automated Planet Finder

Author

Vogt, Steven S., Radovan, Matthew, Kibrick, Robert, Butler, R. Paul, Alcott, Barry, Allen, Steve, Arriagada, Pamela, Bolte, Mike, Burt, Jennifer, Cabak, Jerry, Chloros, Kostas, Cowley, David, Deich, William, Dupraw, Brian, Earthman, Wayne, Epps, Harland, Faber, Sandra, Fischer, Debra, Gates, Elinor, Hilyard, David, Holden, Brad, Johnston, Ken, Keiser, Sandy, Kanto, Dick, Katsuki, Myra, Laiterman, Lee, Lanclos, Kyle, Laughlin, Greg, Lewis, Jeff, Lockwood, Chris, Lynam, Paul, Marcy, Geoffrey, McLean, Maureen, Miller, Joe, Misch, Tony, Peck, Michael, Pfister, Terry, Phillips, Andrew, Rivera, Eugenio, Sandford, Dale, Saylor, Mike, Stover, Richard, Thompson, Matthew, Walp, Bernie, Ward, James, Wareham, John, Wei, Mingzhi, and Wright, Chris

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Automated Planet Finder (APF) is a facility purpose-built for the discovery and characterization of extrasolar planets through high-cadence Doppler velocimetry of the reflex barycentric accelerations of their host stars. Located atop Mt. Hamilton, the APF facility consists of a 2.4-m telescope and its Levy spectrometer, an optical echelle spectrometer optimized for precision Doppler velocimetry. APF features a fixed format spectral range from 374 nm - 970 nm, and delivers a "Throughput" (resolution * slit width product) of 114,000 arc-seconds, with spectral resolutions up to 150,000. Overall system efficiency (fraction of photons incident on the primary mirror that are detected by the science CCD) on blaze at 560 nm in planet-hunting mode is 15%. First-light tests on the RV standard stars HD 185144 and HD 9407 demonstrate sub-meter per second precision (RMS per observation) held over a 3-month period. This paper reviews the basic features of the telescope, dome, and spectrometer, and gives a brief summary of first-light performance., Comment: Accepted at PASP. Version with full resolution available at http://oklo.org/Vogt_APF_2014.pdf

Published
2014
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33. High-Efficiency Pure-Red CsPbI3Quantum Dot Light-Emitting Diodes Enabled by Strongly Electrostatic Potential Solvent and Sequential Ligand Post-treatment Process

Author

Hu, Jingcong, Bi, Chenghao, Ren, Ke, Zhang, Xuetao, Wang, Weiqiang, Ma, Sai, Wei, Mingzhi, Lu, Yue, and Sui, Manling

Abstract

Efficient pure-red emission light-emitting diodes (LEDs) are essential for high-definition displays, yet achieving pure-red emission is hindered by challenges like phase segregation and spectral instability when using halide mixing. Additionally, strongly confined quantum dots (QDs) produced through traditional hot-injection methods face byproduct contamination due to poor solubility of metal halide salts in the solvent octadecene (ODE) at low temperatures. Herein, we introduced a novel method using a benzene-series strongly electrostatic potential solvent instead of ODE to prevent PbI2intermediates and promote their dissolution into [PbI3]−. Increasing methyl groups on benzene yields precisely sized (4.4 ± 0.1 nm) CsPbI3QDs with exceptional properties: a narrow 630 nm PL peak with photoluminescence quantum yield (PLQY) of 97%. Sequential ligand post-treatment optimizes optical and electrical performance of QDs. PeLEDs based on optimized QDs achieve pure-red EL (CIE: 0.700, 0.290) approaching Rec. 2020 standards, with an EQE of 25.2% and T50of 120 min at initial luminance of 107 cd/m2.

Published
2024
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41. Zero-Dimensional/Two-Dimensional Schottky Junction of Mn0.5Cd0.5S/Ti3C2MXene Induces Rapid Electron Transfer and Enrichment for Boosting Photocatalytic H2Production Activity

Author

Zhang, Yue, Zhang, Zhe, Li, Qiancheng, Gao, Xinglong, Lu, Qifang, Guo, Enyan, Si, Conghui, and Wei, Mingzhi

Abstract

Efficient charge separation and transfer in photocatalytic systems continuously enable better water splitting for clean H2evolution. Herein, a feasible in situgrowth hydrothermal strategy by coupling an ultrathin Ti3C2(TC) MXene nanosheet electron acceptor with a Mn0.5Cd0.5S (MCS) nanoparticle donor is introduced to construct a multifunctional donor–acceptor MCS/TC photocatalyst with a strong Schottky junction toward green and sustainable photocatalytic H2production. The strong Schottky junction realizes a rapid carrier directional separation and transportation. The ultrathin TC nanosheets, as an electron acceptor to catalyze proton reduction, can promote the separation of photogenerated electron–hole pairs and provide rich active sites for photocatalytic hydrogen production. Moreover, the optimal MCS/TC-10 (10 wt % TC) photocatalyst provides a highly stable photocatalytic H2activity, up to 3730 μmol h–1g–1, which is 9 times higher than that of Mn0.5Cd0.5S solid solution. This work will inspire the development of design principles for accelerating charge transfer for efficient photocatalytic green H2production.

Published
2024
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43. The DEIMOS spectrograph for the Keck II Telescope: integration and testing

Author

Faber, Sandra M, Phillips, Andrew C, Kibrick, Robert I, Alcott, Barry, Allen, Steven L, Burrous, Jim, Cantrall, T, Clarke, De, Coil, Alison L, Cowley, David J, Davis, Marc, Deich, William TS, Dietsch, Ken, Gilmore, David K, Harper, Carol A, Hilyard, David F, Lewis, Jeffrey P, McVeigh, Molly, Newman, Jeffrey, Osborne, Jack, Schiavon, Ricardo, Stover, Richard J, Tucker, Dean, Wallace, Vernon, Wei, Mingzhi, Wirth, Gregory, and Wright, Christopher A

Subjects
astronomical spectrographs, multi-object spectrographs, astronomical cameras, ground-based instrumentation, CCDs, mosaic detectors, flexure compensation, optical testing
Abstract

The DEIMOS spectrograph is a multi-object spectrograph being built for Keck II. DEIMOS was delivered in February 2002, became operational in May, and is now about three-quarters of the way through its commissioning period. This paper describes the major problems encountered in completing the spectrograph, with particular emphasis on optical quality and image motion. The strategies developed to deal with these problems are described. Overall, commissioning is going well, and it appears that DEIMOS will meet all of its major performance goals.

Published
2003

44. Fully-depleted, back-illuminated charge-coupled devices fabricated on high-resistivity silicon

Author

Holland, Stephen E., Groom, Donald E., Palaio, Nick P., Stover, Richard J., and Wei, Mingzhi

Subjects
Instrumentation -- other, Instrumentation -- other, charge coupled device fully depleted back illuminated
Abstract

Charge-coupled devices (CCD's) have been fabricated on high-resistivity silicon. The resistivity, on the order of 10,000 $\Omega$-cm, allows for depletion depths of several hundred microns. Fully-depleted, back-illuminated operation is achieved by the application of a bias voltage to a ohmic contact on the wafer back side consisting of a thin in-situ doped polycrystalline silicon layer capped by indium tin oxide and silicon dioxide. This thin contact allows for good short wavelength response, while the relatively large depleted thickness results in good near-infrared response.

Published
2002

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