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Lv P, Zhao D, Ma Z, Cong M, Sui Y, Xiao G, Zou B. Pressure-Modulated Interface Engineering toward Realizing Core@Shell Configuration Transition. NANO LETTERS 2023; 23:11982-11988. [PMID: 38051759 DOI: 10.1021/acs.nanolett.3c04359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The strained interface of core@shell nanocrystals (NCs) can effectively modulate the energy level alignment, thereby significantly affecting the optical properties. Herein, the unique photoluminescence (PL) response of doped Mn ions is introduced as a robust probe to detect the targeted pressure-strain relation of CdS@ZnS NCs. Results show that the core experiences actually less pressure than the applied external pressure, attributed to the pressure-induced optimized interface that reduces the compressive strain on core. The pressure difference between core and shell increases the conduction band and valence band offsets and further achieves the core@shell configuration transition from quasi type II to type I. Accordingly, the PL intensity of CdS@ZnS NCs slightly increases, along with a faster blue-shift rate of PL peak under low pressure. This study elucidates the interplay between external physical pressure and interfacial chemical stress for core@shell NCs, leading to precise construction of interface engineering for practical applications.
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Affiliation(s)
- Pengfei Lv
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Dianlong Zhao
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Zhiwei Ma
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Ming Cong
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Yongming Sui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Guanjun Xiao
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Bo Zou
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China
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2
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Pérez LM, Aghoutane N, Laroze D, Díaz P, El-Yadri M, Feddi EM. Unveiling the Role of Donor Impurity Position on the Electronic Properties in Strained Type I and Type II Core/Shell Quantum Dots under Magnetic Field. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6535. [PMID: 37834672 PMCID: PMC10574289 DOI: 10.3390/ma16196535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/19/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023]
Abstract
In this theoretical investigation, we delve into the significant effects of donor impurity position within core/shell quantum dot structures: type I (CdTe/ZnS) and type II (CdTe/CdS). The donor impurity's precise location within both the core and the shell regions is explored to unveil its profound influence on the electronic properties of these nanostructures. Our study investigates the diamagnetic susceptibility and binding energy of the donor impurity while considering the presence of an external magnetic field. Moreover, the lattice mismatch-induced strain between the core and shell materials is carefully examined as it profoundly influences the electronic structure of the quantum dot system. Through detailed calculations, we analyze the strain effects on the conduction and valence bands, as well as the electron and hole energy spectrum within the core/shell quantum dots. The results highlight the significance of donor impurity position as a key factor in shaping the behaviors of impurity binding energy and diamagnetic susceptibility. Furthermore, our findings shed light on the potential for tuning the electronic properties of core/shell quantum dots through precise impurity positioning and strain engineering.
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Affiliation(s)
- Laura M. Pérez
- Departamento de Física, FACI, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile
| | - Noreddine Aghoutane
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile; (N.A.); (D.L.)
| | - David Laroze
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile; (N.A.); (D.L.)
| | - Pablo Díaz
- Departamento de Ciencias Físicas, Universidad de La Frontera, Casilla 54-D, Temuco 4780000, Chile;
| | - Mohamed El-Yadri
- Group of Optoelectronic of Semiconductors and Nanomaterials, ENSAM, Mohammed V University, Rabat 10100, Morocco (E.M.F.)
| | - El Mustapha Feddi
- Group of Optoelectronic of Semiconductors and Nanomaterials, ENSAM, Mohammed V University, Rabat 10100, Morocco (E.M.F.)
- Institute of Applied Physics, Mohammed VI Polytechnic University, Ben Guerir 43150, Morocco
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3
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Just J, Coughlan C, Singh S, Ren H, Müller O, Becker P, Unold T, Ryan KM. Insights into Nucleation and Growth of Colloidal Quaternary Nanocrystals by Multimodal X-ray Analysis. ACS NANO 2021; 15:6439-6447. [PMID: 33770436 PMCID: PMC8291568 DOI: 10.1021/acsnano.0c08617] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/24/2021] [Indexed: 06/12/2023]
Abstract
Copper chalcogenide nanocrystals find applications in photovoltaic inks, bio labels, and thermoelectric materials. We reveal insights in the nucleation and growth during synthesis of anisotropic Cu2ZnSnS4 nanocrystals by simultaneously performing in situ X-ray absorption spectroscopy (XAS) and small-angle X-ray scattering (SAXS). Real-time XAFS reveals that upon thiol injection into the reaction flask, a key copper thiolate intermediate species is formed within fractions of seconds, which decomposes further within a narrow temperature and time window to form copper sulfide nanocrystals. These nanocrystals convert into Cu2ZnSnS4 nanorods by sequentially incorporating Sn and Zn. Real-time SAXS and ex situ TEM of aliquots corroborate these findings. Our work demonstrates how combined in situ X-ray absorption and small-angle X-ray scattering enables the understanding of mechanistic pathways in colloidal nanocrystal formation.
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Affiliation(s)
- Justus Just
- MAX
IV Laboratory, Lund University, Fotongatan 2, 22484 Lund, Sweden
| | - Claudia Coughlan
- Department
of Chemical Sciences and Bernal Institute, University of Limerick, V94T9PX Limerick, Ireland
| | - Shalini Singh
- Department
of Chemical Sciences and Bernal Institute, University of Limerick, V94T9PX Limerick, Ireland
| | - Huan Ren
- Department
of Chemical Sciences and Bernal Institute, University of Limerick, V94T9PX Limerick, Ireland
| | - Oliver Müller
- Stanford
Synchrotron Radiation Lightsource, SLAC National Acceleration Laboratory, Menlo Park, California 94025, United States
| | - Pascal Becker
- Department
of Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Thomas Unold
- Department
of Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Kevin M. Ryan
- Department
of Chemical Sciences and Bernal Institute, University of Limerick, V94T9PX Limerick, Ireland
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4
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Zhao J, Chen B, Wang F. Shedding Light on the Role of Misfit Strain in Controlling Core-Shell Nanocrystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004142. [PMID: 33051904 DOI: 10.1002/adma.202004142] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/21/2020] [Indexed: 05/17/2023]
Abstract
Heteroepitaxial modification of nanomaterials has become a powerful means to create novel functionalities for various applications. One of the most elementary factors in heteroepitaxial nanostructures is the misfit strain arising from mismatched lattices of the constituent parts. Misfit strain not only dictates epitaxy kinetics for diversifying nanocrystal morphologies but also provides rational control over materials properties. In recent years, advances in chemical synthesis along with the rapid development of electron microscopy and X-ray diffraction techniques have enabled a substantial understanding of strain-related processes, which offers theoretical foundation and experimental guidance for researchers to refine heteroepitaxial nanostructures and their properties. Herein, recent investigations on heterogeneous core-shell nanocrystals containing misfit strains are summarized, with a focus on the mechanistic understanding of strain and strain-induced effects such as tuning the epitaxial habit, modulating the optical emission, and enhancing the catalytic activity and magnetic coercivity.
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Affiliation(s)
- Jianxiong Zhao
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| | - Bing Chen
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| | - Feng Wang
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
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5
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Piveteau L, Dirin DN, Gordon CP, Walder BJ, Ong TC, Emsley L, Copéret C, Kovalenko MV. Colloidal-ALD-Grown Core/Shell CdSe/CdS Nanoplatelets as Seen by DNP Enhanced PASS-PIETA NMR Spectroscopy. NANO LETTERS 2020; 20:3003-3018. [PMID: 32078332 PMCID: PMC7227022 DOI: 10.1021/acs.nanolett.9b04870] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ligand exchange and CdS shell growth onto colloidal CdSe nanoplatelets (NPLs) using colloidal atomic layer deposition (c-ALD) were investigated by solid-state nuclear magnetic resonance (NMR) experiments, in particular, dynamic nuclear polarization (DNP) enhanced phase adjusted spinning sidebands-phase incremented echo-train acquisition (PASS-PIETA). The improved sensitivity and resolution of DNP enhanced PASS-PIETA permits the identification and study of the core, shell, and surface species of CdSe and CdSe/CdS core/shell NPLs heterostructures at all stages of c-ALD. The cadmium chemical shielding was found to be proportionally dependent on the number and nature of coordinating chalcogen-based ligands. DFT calculations permitted the separation of the the 111/113Cd chemical shielding into its different components, revealing that the varying strength of paramagnetic and spin-orbit shielding contributions are responsible for the chemical shielding trend of cadmium chalcogenides. Overall, this study points to the roughening and increased chemical disorder at the surface during the shell growth process, which is not readily captured by the conventional characterization tools such as electron microscopy.
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Affiliation(s)
- Laura Piveteau
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Dmitry N. Dirin
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Christopher P. Gordon
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Brennan J. Walder
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ta-Chung Ong
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Lyndon Emsley
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Christophe Copéret
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- E-mail:
| | - Maksym V. Kovalenko
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
- E-mail:
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6
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Fainblat R, Delikanli S, Spee L, Czerny T, Isik F, Sharma VK, Demir HV, Bacher G. Impurity incorporation and exchange interactions in Co2+-doped CdSe/CdS core/shell nanoplatelets. J Chem Phys 2019; 151:224708. [DOI: 10.1063/1.5129391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Savas Delikanli
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Leon Spee
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Tamara Czerny
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Furkan Isik
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Vijay Kumar Sharma
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
| | - Hilmi Volkan Demir
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
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7
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Engineered nanomaterials and human health: Part 1. Preparation, functionalization and characterization (IUPAC Technical Report). PURE APPL CHEM 2018. [DOI: 10.1515/pac-2017-0101] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Abstract
Nanotechnology is a rapidly evolving field, as evidenced by the large number of publications on the synthesis, characterization, and biological/environmental effects of new nano-sized materials. The unique, size-dependent properties of nanomaterials have been exploited in a diverse range of applications and in many examples of nano-enabled consumer products. In this account we focus on Engineered Nanomaterials (ENM), a class of deliberately designed and constructed nano-sized materials. Due to the large volume of publications, we separated the preparation and characterisation of ENM from applications and toxicity into two interconnected documents. Part 1 summarizes nanomaterial terminology and provides an overview of the best practices for their preparation, surface functionalization, and analytical characterization. Part 2 (this issue, Pure Appl. Chem. 2018; 90(8): 1325–1356) focuses on ENM that are used in products that are expected to come in close contact with consumers. It reviews nanomaterials used in therapeutics, diagnostics, and consumer goods and summarizes current nanotoxicology challenges and the current state of nanomaterial regulation, providing insight on the growing public debate on whether the environmental and social costs of nanotechnology outweigh its potential benefits.
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8
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Gabka G, Bujak P, Żukrowski J, Zabost D, Kotwica K, Malinowska K, Ostrowski A, Wielgus I, Lisowski W, Sobczak JW, Przybylski M, Pron A. Non-injection synthesis of monodisperse Cu-Fe-S nanocrystals and their size dependent properties. Phys Chem Chem Phys 2017; 18:15091-101. [PMID: 27197089 DOI: 10.1039/c6cp01887d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
It is demonstrated that ternary Cu-Fe-S nanocrystals differing in composition (from Cu-rich to Fe-rich), structure (chalcopyrite or high bornite) and size can be obtained from a mixture of CuCl, FeCl3, thiourea and oleic acid (OA) in oleylamine (OLA) using the heating up procedure. This new preparation method yields the smallest Cu-Fe-S nanocrystals ever reported to date (1.5 nm for the high bornite structure and 2.7 nm for the chalcopyrite structure). A comparative study of nanocrystals of the same composition (Cu1.6Fe1.0S2.0) but different in size (2.7 nm and 9.3 nm) revealed a pronounced quantum confinement effect, confirmed by three different techniques: UV-vis spectroscopy, cyclic voltammetry and Mössbauer spectroscopy. The optical band gap increased from 0.60 eV in the bulk material to 0.69 eV in the nanocrystals of 9.3 nm size and to 1.39 eV in nanocrystals of 2.7 nm size. The same trend was observed in the electrochemical band gaps, derived from cyclic voltammetry studies (band gaps of 0.74 eV and 1.54 eV). The quantum effect was also manifested in Mössbauer spectroscopy by an abrupt change in the spectrum from a quadrupole doublet to a Zeeman sextet below 10 K, which could be interpreted in terms of the well defined energy states in these nanoparticles, resulting from quantum confinement. The Mössbauer spectroscopic data confirmed, in addition to the results of XPS spectroscopy, the co-existence of Fe(iii) and Fe(ii) in the synthesized nanocrystals. The organic shell composition was investigated by NMR (after dissolution of the inorganic core) and IR spectroscopy. Both methods identified oleylamine (OLA) and 1-octadecene (ODE) as surfacial ligands, the latter being formed in situ via an elimination-hydrogenation reaction occurring between OLA and the nanocrystal surface.
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Affiliation(s)
- Grzegorz Gabka
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Piotr Bujak
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Jan Żukrowski
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Kraków, Poland
| | - Damian Zabost
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Kamil Kotwica
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Karolina Malinowska
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Andrzej Ostrowski
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Ireneusz Wielgus
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
| | - Wojciech Lisowski
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Janusz W Sobczak
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Marek Przybylski
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Kraków, Poland and Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Kraków, Poland
| | - Adam Pron
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
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9
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Antanovich A, Achtstein AW, Matsukovich A, Prudnikau A, Bhaskar P, Gurin V, Molinari M, Artemyev M. A strain-induced exciton transition energy shift in CdSe nanoplatelets: the impact of an organic ligand shell. NANOSCALE 2017; 9:18042-18053. [PMID: 29131231 DOI: 10.1039/c7nr05065h] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study the influence of surface passivating ligands on the optical and structural properties of zinc blende CdSe nanoplatelets. Ligand exchange of native oleic acid with aliphatic thiol or phosphonic acid on the surface of nanoplatelets results in a large shift of exciton transition energy for up to 240 meV. Ligand exchange also leads to structural changes (strain) in the nanoplatelet's core analysed by wide-angle X-ray diffraction. By correlating the experimental data with theoretical calculations we demonstrate that the exciton energy shift is mainly caused by the ligand-induced anisotropic transformation of the crystalline structure altering the well width of the CdSe core. Further the exciton reduced mass in these CdSe quantum wells is determined by a new method and this agrees well with the expected values substantiating that ligand-strain induced changes in the colloidal quantum well thickness are responsible for the observed spectral shifts. Our findings are important for theoretical modeling of other anisotropically strained systems and demonstrate an approach to tune the optical properties of 2D semiconductor nanocrystals over a broad region thus widening the range of possible applications of AIIBVI nanoplatelets in optics and optoelectronics.
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Affiliation(s)
- A Antanovich
- Research Institute for Physical Chemical Problems of the Belarusian State University, 220006 Minsk, Belarus.
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10
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Efimova AA, Grokhovskaya TE, Efimov AV. Sorption of CdTe and Au nanoparticles by microporous isotactic polypropylene. MENDELEEV COMMUNICATIONS 2017. [DOI: 10.1016/j.mencom.2017.05.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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11
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Karabudak E, Brookes E, Lesnyak V, Gaponik N, Eychmüller A, Walter J, Segets D, Peukert W, Wohlleben W, Demeler B, Cölfen H. Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution with Subnanometer Resolution. Angew Chem Int Ed Engl 2016; 55:11770-4. [PMID: 27461742 PMCID: PMC5148131 DOI: 10.1002/anie.201603844] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Indexed: 11/11/2022]
Abstract
We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.
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Affiliation(s)
- Engin Karabudak
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm, Am Mühlenberg, 14424, Potsdam, Germany
- Izmir Institute of Technology, Chemistry Department, 35430, Izmir, Turkey
| | - Emre Brookes
- University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3901, USA
| | - Vladimir Lesnyak
- Physikalische Chemie, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany
| | - Nikolai Gaponik
- Physikalische Chemie, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany
| | | | - Johannes Walter
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | - Doris Segets
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | | | - Borries Demeler
- University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3901, USA.
| | - Helmut Cölfen
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm, Am Mühlenberg, 14424, Potsdam, Germany.
- Universität Konstanz, Physikalische Chemie, Universitätsstrasse 10, 78457, Konstanz, Germany.
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12
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Karabudak E, Brookes E, Lesnyak V, Gaponik N, Eychmüller A, Walter J, Segets D, Peukert W, Wohlleben W, Demeler B, Cölfen H. Simultane Bestimmung spektraler Eigenschaften und Größen von multiplen Partikeln in Lösung mit Subnanometer‐Auflösung. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Engin Karabudak
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm Am Mühlenberg 14424 Potsdam Deutschland
- Izmir Institute of Technology, Chemistry Department 35430 Izmir Türkei
| | - Emre Brookes
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio TX 78229-3901 USA
| | - Vladimir Lesnyak
- Physikalische Chemie, TU Dresden Bergstraße 66b 01062 Dresden Deutschland
| | - Nikolai Gaponik
- Physikalische Chemie, TU Dresden Bergstraße 66b 01062 Dresden Deutschland
| | | | - Johannes Walter
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | - Doris Segets
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | - Wolfgang Peukert
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | | | - Borries Demeler
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio TX 78229-3901 USA
| | - Helmut Cölfen
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm Am Mühlenberg 14424 Potsdam Deutschland
- Universität Konstanz, Physikalische Chemie Universitätsstraße 10 78457 Konstanz Deutschland
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Kapush OA, Trishchuk LI, Tomashik VN, Tomashik ZF, Budzulyak SI, Boruk SD, Ermakov VN, Demchina LA. Effect of medium pH on the optical properties of CdTe nanocrystals at colloidal synthesis and postsynthetic treatment. RUSS J INORG CHEM+ 2016. [DOI: 10.1134/s0036023616050089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Beane GA, Gong K, Kelley DF. Auger and Carrier Trapping Dynamics in Core/Shell Quantum Dots Having Sharp and Alloyed Interfaces. ACS NANO 2016; 10:3755-3765. [PMID: 26895220 DOI: 10.1021/acsnano.6b00370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The role of interface sharpness in controlling the excited state dynamics in CdSe/ZnSe core/shell particles is examined here. Particles composed of CdSe/ZnSe with 2.4-4.0 nm diameter cores and approximately 4 monolayer shells are synthesized at relatively low temperature, ensuring a sharp core-shell interface. Subsequent annealing results in cadmium and zinc interdiffusion, softening the interface. TEM imaging and absorption spectra reveal that annealing results in no change in the particle sizes. Annealing results in a 5-10 nm blue shift in the absorption spectrum, which is compared to calculated spectral shifts to characterize the extent of metal interdiffusion. The one- and two-photon dynamics are measured using time-resolved absorption spectroscopy. We find that biexcitons undergo biexponential decays, with fast and slow decay times differing by about an order of magnitude. The relative magnitudes of the fast and slow components depend on the sharpness of the core-shell interface, with larger fast component amplitudes associated with a sharp core-shell interface. The slow component is assigned to Auger recombination of band edge carriers and the fast decay component to Auger recombination of holes that are trapped in defects produced by lattice strain. Annealing of these particles softens the core-shell interface and thereby reduces the amount of lattice strain and diminishes the magnitude of the fast decay component. The time constant of the slow biexciton Auger recombination component changes only slightly upon softening of the core-shell interface.
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Affiliation(s)
- Gary A Beane
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Ke Gong
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
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15
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Gong K, Kelley DF. A predictive model of shell morphology in CdSe/CdS core/shell quantum dots. J Chem Phys 2015; 141:194704. [PMID: 25416902 DOI: 10.1063/1.4901428] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Lattice mismatch in core/shell nanoparticles occurs when the core and shell materials have different lattice parameters. When there is a significant lattice mismatch, a coherent core-shell interface results in substantial lattice strain energy, which can affect the shell morphology. The shell can be of uniform thickness or can be rough, having thin and thick regions. A smooth shell minimizes the surface energy at the expense of increased lattice strain energy and a rough shell does the opposite. A quantitative treatment of the lattice strain energy in determining the shell morphology of CdSe/CdS core/shell nanoparticles is presented here. We use the inhomogeneity in hole tunneling rates through the shell to adsorbed hole acceptors to quantify the extent of shell thickness inhomogeneity. The results can be understood in terms of a model based on elastic continuum calculations, which indicate that the lattice strain energy depends on both core size and shell thickness. The model assumes thermodynamic equilibrium, i.e., that the shell morphology corresponds to a minimum total (lattice strain plus surface) energy. Comparison with the experimental results indicates that CdSe/CdS nanoparticles undergo an abrupt transition from smooth to rough shells when the total lattice strain energy exceeds about 27 eV or the strain energy density exceeds 0.59 eV/nm(2). We also find that the predictions of this model are not followed for CdSe/CdS nanoparticles when the shell is deposited at very low temperature and therefore equilibrium is not established.
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Affiliation(s)
- Ke Gong
- Chemistry and Chemical Biology, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA
| | - David F Kelley
- Chemistry and Chemical Biology, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA
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16
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Gong K, Kelley DF. Lattice Strain Limit for Uniform Shell Deposition in Zincblende CdSe/CdS Quantum Dots. J Phys Chem Lett 2015; 6:1559-62. [PMID: 26263313 DOI: 10.1021/acs.jpclett.5b00566] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The effects of lattice strain on the spectroscopy and photoluminescence quantum yields of zincblende CdSe/CdS core/shell quantum dots are examined. The quantum yields are measured as a function of core size and shell thickness. High quantum yields are achieved as long as the lattice strain energy density is below ~0.85 eV/nm(2), which is considerably greater than the limiting value of 0.59 eV/nm(2) for thermodynamic stability of a smooth, defect-free shell, as previously reported (J. Chem. Phys. 2014, 141, 194704). Thus, core/shell quantum dots having strain energy densities between 0.59 and 0.85 eV/nm(2) can have very high PL QYs but are metastable with respect to surface defect formation. Such metastable core/shell QDs can be produced by shell deposition at comparatively low temperatures (<140 °C). Annealing of these particles causes partial loss of core pressure and a red shift of the spectrum.
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Affiliation(s)
- Ke Gong
- Chemistry and Chemical Biology, University of California Merced, 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California Merced, 5200 North Lake Road, Merced, California 95343, United States
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17
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Doan-Nguyen VVT, Carroll PJ, Murray CB. Structure determination and modeling of monoclinic trioctylphosphine oxide. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2015; 71:239-41. [DOI: 10.1107/s2053229615003009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/11/2015] [Indexed: 11/11/2022]
Abstract
Trioctylphosphine oxide (TOPO), C24H51OP, was recrystallized from ambient evaporation in acetone. TOPO single crystals form with a monoclinicP21/cstructure. Fourier transform IR (FT–IR) spectroscopy captures the characteristic stretching modes from the seven methylene groups, the phosphoryl P=O bond, and the phosphoryl–carbon bond.
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18
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Li J, Kempken B, Dzhagan V, Zahn DRT, Grzelak J, Mackowski S, Parisi J, Kolny-Olesiak J. Alloyed CuInS2–ZnS nanorods: synthesis, structure and optical properties. CrystEngComm 2015. [DOI: 10.1039/c5ce00380f] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Baldi A, Narayan TC, Koh AL, Dionne JA. In situ detection of hydrogen-induced phase transitions in individual palladium nanocrystals. NATURE MATERIALS 2014; 13:1143-8. [PMID: 25194700 DOI: 10.1038/nmat4086] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 08/08/2014] [Indexed: 05/26/2023]
Abstract
Many energy- and information-storage processes rely on phase changes of nanomaterials in reactive environments. Compared to their bulk counterparts, nanostructured materials seem to exhibit faster charging and discharging kinetics, extended life cycles, and size-tunable thermodynamics. However, in ensemble studies of these materials, it is often difficult to discriminate between intrinsic size-dependent properties and effects due to sample size and shape dispersity. Here, we detect the phase transitions of individual palladium nanocrystals during hydrogen absorption and desorption, using in situ electron energy-loss spectroscopy in an environmental transmission electron microscope. In contrast to ensemble measurements, we find that palladium nanocrystals undergo sharp transitions between the α and β phases, and that surface effects dictate the size dependence of the hydrogen absorption pressures. Our results provide a general framework for monitoring phase transitions in individual nanocrystals in a reactive environment and highlight the importance of single-particle approaches for the characterization of nanostructured materials.
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Affiliation(s)
- Andrea Baldi
- 1] Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA [2] FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
| | - Tarun C Narayan
- Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA
| | - Ai Leen Koh
- Stanford Nanocharacterization Laboratory, Stanford University, Stanford, California 94305, USA
| | - Jennifer A Dionne
- 1] Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA [2] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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20
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Bian K, Bassett W, Wang Z, Hanrath T. The Strongest Particle: Size-Dependent Elastic Strength and Debye Temperature of PbS Nanocrystals. J Phys Chem Lett 2014; 5:3688-3693. [PMID: 26278737 DOI: 10.1021/jz501797y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigated the elastic compressibility of PbS nanocrystals (NCs) pressurized in a diamond anvil cell and simultaneously probed the structure using synchrotron-based X-ray diffraction. The compressibility of PbS NCs exhibits bimodal size dependence. The elastic modulus of small NCs increases with increasing diameter and peaks near a particle diameter of approximately 7 nm. For large NCs the elastic modulus decreases toward the bulk value with increasing NC diameter. We explain the bimodal size-dependence of the elastic modulus in terms of a core-shell model based on distinct elasticity of the crystal near the surface and in the core of the particle. We combined insights into the size-dependent elasticity and lattice spacing to determine the Debye temperature of PbS NCs as a function of particle diameter. Understanding the size-dependent elasticity of defect-free colloidal NCs provides new insights into their crystal structure and mechanical properties.
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Affiliation(s)
- Kaifu Bian
- †School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States
| | - William Bassett
- †School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States
| | - Zhongwu Wang
- †School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States
| | - Tobias Hanrath
- †School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States
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21
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Comparative syntheses of tetracycline-imprinted polymeric silicate and acrylate on CdTe quantum dots as fluorescent sensors. Biosens Bioelectron 2014; 61:471-7. [DOI: 10.1016/j.bios.2014.05.058] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/28/2014] [Accepted: 05/29/2014] [Indexed: 11/23/2022]
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22
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Lin YC, Chou WC, Susha AS, Kershaw SV, Rogach AL. Photoluminescence and time-resolved carrier dynamics in thiol-capped CdTe nanocrystals under high pressure. NANOSCALE 2013; 5:3400-3405. [PMID: 23471137 DOI: 10.1039/c3nr33928a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The application of static high pressure provides a method for precisely controlling and investigating many fundamental and unique properties of semiconductor nanocrystals (NCs). This study systematically investigates the high-pressure photoluminescence (PL) and time-resolved carrier dynamics of thiol-capped CdTe NCs of different sizes, at different concentrations, and in various stress environments. The zincblende-to-rocksalt phase transition in thiol-capped CdTe NCs is observed at a pressure far in excess of the bulk phase transition pressure. Additionally, the process of transformation depends strongly on NC size, and the phase transition pressure increases with NC size. These peculiar phenomena are attributed to the distinctive bonding of thiols to the NC surface. In a nonhydrostatic environment, considerable flattening of the PL energy of CdTe NC powder is observed above 3.0 GPa. Furthermore, asymmetric and double-peak PL emissions are obtained from a concentrated solution of CdTe NCs under hydrostatic pressure, implying the feasibility of pressure-induced interparticle coupling.
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Affiliation(s)
- Yan-Cheng Lin
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan.
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23
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Gomes SA, Vieira CS, Almeida DB, Santos-Mallet JR, Menna-Barreto RFS, Cesar CL, Feder D. CdTe and CdSe quantum dots cytotoxicity: a comparative study on microorganisms. SENSORS 2011; 11:11664-78. [PMID: 22247686 PMCID: PMC3252003 DOI: 10.3390/s111211664] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 11/26/2011] [Accepted: 12/09/2011] [Indexed: 11/16/2022]
Abstract
Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe) or cadmium selenium (CdSe) forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus.
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Affiliation(s)
- Suzete A.O. Gomes
- Laboratório de Biologia de Insetos, GBG, Universidade Federal Fluminense—UFF, Niterói, RJ, CEP: 24210-130, Brazil; E-Mail: (S.A.O.G.)
| | - Cecilia Stahl Vieira
- Laboratório de Transmissores de Leishmanioses, Setor de Entomologia Médica e Forense, IOC-FIOCRUZ, Rio de Janeiro, RJ, CEP: 21040-360, Brazil; E-Mails: (C.S.V.); (J.R.S.-M.)
| | - Diogo B. Almeida
- Laboratório de Aplicações Biomédicas de Lasers, Departamento de Eletrônica Quântica, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, CEP: 13083-970, Brazil; E-Mails: (D.B.A.); (C.L.C.)
| | - Jacenir R. Santos-Mallet
- Laboratório de Transmissores de Leishmanioses, Setor de Entomologia Médica e Forense, IOC-FIOCRUZ, Rio de Janeiro, RJ, CEP: 21040-360, Brazil; E-Mails: (C.S.V.); (J.R.S.-M.)
| | - Rubem F. S. Menna-Barreto
- Laboratório de Biologia Celular, IOC-FIOCRUZ, Rio de Janeiro, RJ, CEP: 21040-360, Brazil; E-Mail: (R.F.S.M.-B.)
| | - Carlos L. Cesar
- Laboratório de Aplicações Biomédicas de Lasers, Departamento de Eletrônica Quântica, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, CEP: 13083-970, Brazil; E-Mails: (D.B.A.); (C.L.C.)
| | - Denise Feder
- Laboratório de Biologia de Insetos, GBG, Universidade Federal Fluminense—UFF, Niterói, RJ, CEP: 24210-130, Brazil; E-Mail: (S.A.O.G.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +55-21-2629-2285
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24
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Gasperini A, Malachias A, Fabbris G, Kellermann G, Gobbi A, Avendaño E, Azevedo GDM. Investigation of indirect structural and chemical parameters of GeSi nanoparticles in a silica matrix by combined synchrotron radiation techniques. J Appl Crystallogr 2011. [DOI: 10.1107/s0021889811049302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The formation of GeSi nanoparticles on an SiO2matrix is studied here by synchrotron-based techniques. The shape, average diameter and size dispersion were obtained from grazing-incidence small-angle X-ray scattering data. X-ray diffraction measurements were used to obtain crystallite sizes and compositionviaresonant (anomalous) measurements. By using these techniques as input for extended X-ray absorption fine structure analysis, the local composition surrounding the Ge atoms is investigated. Although the results for each of the methods above are commonly analyzed separately, the combination of such techniques leads to an improved understanding of nanoparticle structural and chemical properties. Crucial indirect parameters that cannot be quantified by other means are accessed in this work, such as local strain, the possibility of forming core–shell structures, the fraction of Ge atoms diluted in the matrix (not forming nanoparticles), the amorphous and crystalline Ge fractions, and the relative population of nanoparticles with single and multiple crystalline domains.
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25
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Rogach AL, Eychmüller A, Rockenberger J, Kornowski A, Weller H, Troger L, Gao MY, Harrison MT, Kershaw SV, Burt MG. Thiol-Capped CdSe and CdTe Nanoclusters: Synthesis by a Wet Chemical Route, Structural and Optical Properties. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-536-365] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractCdSe and CdTe nanoclusters were formed in aqueous solutions at moderate temperatures by a wet chemical route in the presence of thiols as effective stabilizing agents. The nature of the stabilizing agent (thioalcohols or thioacids) had an important influence on the particle size and largely determined the photoluminescence properties. The nanoclusters were characterized by means of UV-vis absorption and photoluminescence spectroscopy, powder X-ray diffraction, high resolution transmission electron microscopy, and extended X-ray absorption fine structure measurements. CdSe and CdTe nanoclusters were crystalline, in the cubic zincblende phase, with mean sizes in the range of 2 to 5 nm depending on the preparative conditions and the postpreparative size-selective fractionation, and showed pronounced electronic transitions in the absorption spectra. Thioglycerol-stabilized CdTe nanoclusters possessed sharp band-egde photoluminescence being tunable with particle size.
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26
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Nonoguchi Y, Nakashima T, Tanaka A, Miyabayashi K, Miyake M, Kawai T. Oligomerization of cadmium chalcogenide nanocrystals into CdTe-containing superlattice chains. Chem Commun (Camb) 2011; 47:11270-2. [DOI: 10.1039/c1cc14103a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Stamatoiu O, Mirzaei J, Feng X, Hegmann T. Nanoparticles in liquid crystals and liquid crystalline nanoparticles. Top Curr Chem (Cham) 2011; 318:331-93. [PMID: 21928012 DOI: 10.1007/128_2011_233] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Combinations of liquid crystals and materials with unique features as well as properties at the nanoscale are reviewed. Particular attention is paid to recent developments, i.e., since 2007, in areas ranging from liquid crystal-nanoparticle dispersions to nanomaterials forming liquid crystalline phases after surface modification with mesogenic or promesogenic moieties. Experimental and synthetic approaches are summarized, design strategies compared, and potential as well as existing applications discussed. Finally, a critical outlook into the future of this fascinating field of liquid crystal research is provided.
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Affiliation(s)
- Oana Stamatoiu
- Department of Chemistry, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
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28
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Mostafa S, Behafarid F, Croy JR, Ono LK, Li L, Yang JC, Frenkel AI, Cuenya BR. Shape-dependent catalytic properties of Pt nanoparticles. J Am Chem Soc 2010. [PMID: 20949968 DOI: 10.1103/physrevb.82.155450] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in catalysis research. In order to achieve this elusive goal, fundamental understanding of the geometric and electronic structure of these complex systems at the atomic level must be obtained. This article reports the influence of the nanoparticle shape on the reactivity of Pt nanocatalysts supported on γ-Al(2)O(3). Nanoparticles with analogous average size distributions (∼0.8-1 nm), but with different shapes, synthesized by inverse micelle encapsulation, were found to display distinct reactivities for the oxidation of 2-propanol. A correlation between the number of undercoordinated atoms at the nanoparticle surface and the onset temperature for 2-propanol oxidation was observed, demonstrating that catalytic properties can be controlled through shape-selective synthesis.
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Affiliation(s)
- Simon Mostafa
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
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Abstract
Colloidal heteronanocrystals (HNCs) can be regarded as solution-grown inorganic-organic hybrid nanomaterials, since they consist of inorganic nanoparticles that are coated with a layer of organic ligand molecules. The hybrid nature of these nanostructures provides great flexibility in engineering their physical and chemical properties. The inorganic particles are heterostructured, i.e. they comprise two (or more) different materials joined together, what gives them remarkable and unique properties that can be controlled by the composition, size and shape of each component of the HNC. The interaction between the inorganic component and the organic ligand molecules allows the size and shape of the HNCs to be controlled and gives rise to novel properties. Moreover, the organic surfactant layer opens up the possibility of surface chemistry manipulation, making it possible to tailor a number of properties. These features have turned colloidal HNCs into promising materials for a number of applications, spurring a growing interest on the investigation of their preparation and properties. This critical review provides an overview of recent developments in this rapidly expanding field, with emphasis on semiconductor HNCs (e.g., quantum dots and quantum rods). In addition to defining the state of the art and highlighting the key issues in the field, this review addresses the fundamental physical and chemical principles needed to understand the properties and preparation of colloidal HNCs (283 references).
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Affiliation(s)
- Celso de Mello Donegá
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, Netherlands.
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30
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Chen H, Lin L, Lin Z, Guo G, Lin JM. Chemiluminescence Arising from the Decomposition of Peroxymonocarbonate and Enhanced by CdTe Quantum Dots. J Phys Chem A 2010; 114:10049-58. [DOI: 10.1021/jp104060x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hui Chen
- Department of Chemistry, Tsinghua University, Beijing 100084, China, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Ling Lin
- Department of Chemistry, Tsinghua University, Beijing 100084, China, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhen Lin
- Department of Chemistry, Tsinghua University, Beijing 100084, China, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Guangsheng Guo
- Department of Chemistry, Tsinghua University, Beijing 100084, China, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jin-Ming Lin
- Department of Chemistry, Tsinghua University, Beijing 100084, China, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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31
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Zhou Y, Yang M, Sun K, Tang Z, Kotov NA. Similar topological origin of chiral centers in organic and nanoscale inorganic structures: effect of stabilizer chirality on optical isomerism and growth of CdTe nanocrystals. J Am Chem Soc 2010; 132:6006-13. [PMID: 20384329 DOI: 10.1021/ja906894r] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is observed in this study that the chirality of cysteine stabilizers has a distinct effect on both the growth kinetics and the optical properties of CdTe nanocrystals synthesized in aqueous solution. The effect was studied by circular dichroism spectroscopy, temporal UV-vis spectroscopy, photoluminescence spectroscopy, and several other microscopy and spectroscopic techniques including atomic modeling. Detailed analysis of the entirety of experimental and theoretical data led to the hypothesis that the atomic origin of chiral sites in nanocrystals is topologically similar to that in organic compounds. Since atoms in CdTe nanocrystals are arranged as tetrahedrons, chirality can occur when all four atomic positions have chemical differences. This can happen in apexes of nanocrystals, which are the most susceptible to chemical modification and substitution. Quantum mechanical calculations reveal that the thermodynamically preferred configuration of CdTe nanocrystals is S type when the stabilizer is D-cysteine and R type when L-cysteine is used as a stabilizer, which correlates well with the experimental kinetics of particle growth. These findings help clarify the nature of chirality in inorganic nanomaterials, the methods of selective production of optical isomers of nanocrystals, the influence of chiral biomolecules on the nanoscale crystallization, and practical perspectives of chiral nanomaterials for optics and medicine.
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Affiliation(s)
- Yunlong Zhou
- National Centre for Nanoscience and Technology, Beijing 100190, People's Republic of China
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32
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Rockenberger J, Tröger L, Rogach AL, Tischer M, Grundmann M, Weller H, Eychmüller A. An EXAFS study on thiolcapped CdTe nanocrystals. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19981021110] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Thomson JW, Cademartiri L, MacDonald M, Petrov S, Calestani G, Zhang P, Ozin GA. Ultrathin Bi2S3 Nanowires: Surface and Core Structure at the Cluster-Nanocrystal Transition. J Am Chem Soc 2010; 132:9058-68. [DOI: 10.1021/ja101908k] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Jordan W. Thomson
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Ludovico Cademartiri
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Mark MacDonald
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Srebri Petrov
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Gianluca Calestani
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Peng Zhang
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
| | - Geoffrey A. Ozin
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, Department of Chemistry, Dalhousie University, Halifax, NS, Canada, and Dipartimento di Chimica GIAF, Universita’ di Parma, viale Usberti 17, Parma, Italy
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34
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Ferreira DL, Silva FO, Viol LCDS, Licínio P, Schiavon MA, Alves JLA. Theoretical and experimental studies of stressed nanoparticles of II-VI semiconductors. J Chem Phys 2010; 132:014107. [DOI: 10.1063/1.3280074] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- D Lourençoni Ferreira
- Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, C. P. 702, 30123-970, Belo Horizonte, Minas Gerais, Brazil.
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35
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Gaponik N, Rogach AL. Thiol-capped CdTe nanocrystals: progress and perspectives of the related research fields. Phys Chem Chem Phys 2010; 12:8685-93. [DOI: 10.1039/c000916d] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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36
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Vaqueiro P. Hybrid materials through linkage of chalcogenide tetrahedral clusters. Dalton Trans 2010; 39:5965-72. [DOI: 10.1039/c000130a] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nakashima T, Kobayashi Y, Kawai T. Optical activity and chiral memory of thiol-capped CdTe nanocrystals. J Am Chem Soc 2009; 131:10342-3. [PMID: 19588974 DOI: 10.1021/ja902800f] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CdTe nanocrystals (NCs) passivated with chiral ligands d- and l-cysteinemethylester hydrochloride were prepared and observed to exhibit characteristic CD profiles with symmetrical mirror images depending on the chirality of the capping ligand. The optical activity of CdTe NCs is shown to originate from the distorted CdS shell including chiral capping molecules. The chirality of the NC surface is maintained even after ligand exchange with an achiral thiol, providing an unprecedented chiral memory effect.
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Affiliation(s)
- Takuya Nakashima
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
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38
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Two-dimensional assembly of the type Cd10Te4 thiolate cluster with 4,4′-trimethylenedipyridine. INORG CHEM COMMUN 2009. [DOI: 10.1016/j.inoche.2009.08.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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39
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Farias PMA, Santos BS, Fontes A. Semiconductor fluorescent quantum dots: efficient biolabels in cancer diagnostics. Methods Mol Biol 2009; 544:407-19. [PMID: 19488715 DOI: 10.1007/978-1-59745-483-4_27] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We present and discuss results and features related to the synthesis of water-soluble semiconductor quantum dots and their application as fluorescent biomarkers in cancer diagnostics. We have prepared and applied different core-shell quantum dots, such as cadmium telluride-cadmium sulfide, CdTe-CdS, and cadmium sulfide-cadmium hydroxide, CdS/Cd(OH)(2), in living healthy and neoplastic cells and tissues samples. The CdS/Cd(OH)(2) quantum dots presented the best results, maintaining high levels of luminescence as well as high photostability in cells and tissues. Labeled tissues and cells were analyzed by their resulting fluorescence, via conventional fluorescence microscopy or via laser scanning confocal microscopy. The procedure presented in this work was shown to be efficient as a potential tool for fast and precise cancer diagnostics.
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Affiliation(s)
- Patricia M A Farias
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Cidade Universitária, Recife, PE, Brazil.
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40
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Dagtepe P, Chikan V. Effect of Cd/Te Ratio on the Formation of CdTe Magic-Sized Quantum Dots during Aggregation. J Phys Chem A 2008; 112:9304-11. [DOI: 10.1021/jp802254n] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pinar Dagtepe
- Kansas State University, Department of Chemistry, Manhattan, Kansas 66506-3701
| | - Viktor Chikan
- Kansas State University, Department of Chemistry, Manhattan, Kansas 66506-3701
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41
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Shang Q, Wang H, Yu H, Shan G, Yan R. Effect of phenylalanine on photoluminescence and stability of CdTe nanocrystals capped with thioglycolic acid. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2006.07.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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42
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43
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Lobo A, Borchert H, Talapin D, Weller H, Möller T. Surface oxidation of CdTe nanocrystals—A high resolution core-level photoelectron spectroscopy study. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.11.068] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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44
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Duan HL, Karihaloo BL, Wang J, Yi X. Strain distributions in nano-onions with uniform and non-uniform compositions. NANOTECHNOLOGY 2006; 17:3380-3387. [PMID: 19661579 DOI: 10.1088/0957-4484/17/14/007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nano-onions are ellipsoidal or spherical particles consisting of a core surrounded by concentric shells of nanometre size. Nano-onions produced by self-assembly and colloidal techniques have different structures and compositions, and thus differ in the state of strains. The mismatch of the thermal expansion coefficients and lattice constants between neighbouring shells induces stress/strain fields in the core and shells, which in turn affect their physical/mechanical properties and/or the properties of the composites containing them. In this paper, the strains in embedded and free-standing nano-onions with uniform and non-uniform compositions are studied in detail. It is found that the strains in the nano-onions can be modified by adjusting their compositions and structures. The results are useful for the band structure engineering of semiconductor nano-onions.
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Affiliation(s)
- H L Duan
- School of Engineering, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, UK. LTCS and College of Engineering, Peking University, Beijing 100871, People's Republic of China
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45
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Gattás-Asfura KM, Naistat DM, Leblanc RM. Color change of toluidine blue induced by polyanionic quantum dots. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.10.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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46
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Gilbert B, Huang F, Lin Z, Goodell C, Zhang H, Banfield JF. Surface chemistry controls crystallinity of ZnS nanoparticles. NANO LETTERS 2006; 6:605-10. [PMID: 16608252 DOI: 10.1021/nl052201c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Combined small-angle and high energy wide-angle X-ray scattering measurements of nanoparticle size and structure permit interior strain and disorder to be observed directly in the real-space pair distribution function (PDF). PDF analysis showed that samples of ZnS nanoparticles with similar mean diameters (3.2-3.6 nm) but synthesized and treated with different low-temperature procedures possess a dramatic range of interior disorder. We used Fourier transform infrared spectroscopy to detect the surface species and the nature of surface chemical interactions. Our results suggest that there is a direct correlation between the strength of surface-ligand interactions and interior crystallinity.
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Affiliation(s)
- Benjamin Gilbert
- Department of Earth and Planetary Sciences, University of California, Berkeley, California 94720, USA.
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47
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Schöps O, Le Thomas N, Woggon U, Artemyev MV. Recombination Dynamics of CdTe/CdS Core−Shell Nanocrystals. J Phys Chem B 2006; 110:2074-9. [PMID: 16471785 DOI: 10.1021/jp0557013] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The recombination dynamics of zinc-blende-type, deep-red emitting CdTe/CdS core-shell nanocrystals is studied over a wide temperature range. Two characteristic decay regimes are found: a temperature-dependent decay component of a few nanoseconds and a long-living temperature-independent component of approximately 315 ns. The average decay time of the exciton states changes from 20 to 5ns when the temperature is increased from 15 to 295 K. At low temperatures, the observed decay behavior is assigned to thermally induced population and decay of the allowed exchange-split exciton states. At temperatures above T>100 K, nonradiative decay channels involving phonons start to contribute to the exciton recombination. The observed broad distribution in decay times, monitored by stretched exponential fitting functions, we explain by variations in the electron-hole overlap caused by a partly incomplete CdTe/CdS core-shell structure and the nearly energy-degenerated bright and dark state superposition.
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Affiliation(s)
- O Schöps
- Fachbereich Physik, Universität Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
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48
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Boldt K, Bruns OT, Gaponik N, Eychmüller A. Comparative Examination of the Stability of Semiconductor Quantum Dots in Various Biochemical Buffers. J Phys Chem B 2006; 110:1959-63. [PMID: 16471768 DOI: 10.1021/jp056371p] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Due to their greater photostability compared to established organic fluorescence markers, semiconductor quantum dots provide an attractive alternative for the biolabeling of living cells. On the basis of a comparative investigation using differently sized thiol-stabilized CdTe nanocrystals in a variety of commonly used biological buffers, a method is developed to quantify the stability of such a multicomponent system. Above a certain critical size, the intensity of the photoluminescence of the nanocrystals is found to diminish with pseudo-zero-order kinetics, whereas for specific combinations of particle size, ligand, and buffer there appears to be no decay below this critical particle size, pointing out the necessity for thorough investigations of this kind in the view of prospect applications of semiconductor nanocrystals in the area of biolabeling.
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Affiliation(s)
- Klaus Boldt
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
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Fleischer H, Dienes Y, Mathiasch B, Schmitt V, Schollmeyer D. Cysteamine and Its Homoleptic Complexes with Group 12 Metal Ions. Differences in the Coordination Chemistry of ZnII, CdII, and HgII with a Small N,S-Donor Ligand. Inorg Chem 2005; 44:8087-96. [PMID: 16241159 DOI: 10.1021/ic050814m] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2-Ammoniumethanethiolate, (-)SCH(2)CH(2)NH(3)(+), the first structurally characterized zwitterionic ammoniumthiolate, is the stable form of cysteamine (HL) in the solid state and in aqueous solution. Reactions of ZnCl(2), Cd(Oac)(2), and HgCl(2) with cysteamine and NaOH in a 1:2:2 ratio, respectively, lead to the homoleptic complexes ML(2). Their single-crystal X-ray structures demonstrate basic differences in the coordination chemistry of Zn(II), Cd(II), and Hg(II). While chelating N,S-coordination modes are found for all metal ions, Zn(II) forms a mononuclear complex with a distorted tetrahedral Zn(N(2)S(2)) coordination mode, whereas Hg(II) displays a dimer with Hg(N(2)S(2)) coordinated monomers being connected by two long Hg...S contacts. Solid-state (199)Hg NMR spectra of HgL(2) and [Hg(HL)(2)]Cl(2) reveal a low-field shift of the signals with increasing coordination number. Strong and nearly symmetric Cd-S-Cd bridges in solid CdL(2) lead to a chain structure, Cd(II) displaying a distorted square pyramidal Cd(N(2)S(3)) coordination mode. The ab initio [MP2/LANL2DZ(d,f)] structures of isolated ML(2) show a change from a distorted tetrahedral to bisphenoidal coordination mode in the sequence Zn(II)-Cd(II)-Hg(II). A natural bond orbital analysis showed a high ionic character for the M-S bonds and suggests that the S-M-S fragment is best described by a 3c4e bond. The strength of the M...N interactions and the stability of ML(2) toward decomposition to M and L-L decreases in the sequence Zn > Cd > Hg. Ab initio calculations further suggest that a tetrahedral S-M-S angle stabilizes Zn(II) against substitution by Cd(II) and Hg(II) in a M(N(2)S(2)) environment. Such geometry is provided in zinc-finger proteins, as was found by a database survey.
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Affiliation(s)
- Holger Fleischer
- Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg Universität Mainz, Germany.
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50
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Yaroslavov AA, Sinani VA, Efimova AA, Yaroslavova EG, Rakhnyanskaya AA, Ermakov YA, Kotov NA. What Is the Effective Charge of TGA-Stabilized CdTe Nanocolloids? J Am Chem Soc 2005; 127:7322-3. [PMID: 15898775 DOI: 10.1021/ja051095d] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The surface charge of semiconductor nanoparticles, Q, is an important parameter which determines their electrokinetic behavior, stability in water and polar solvents, functions of optical and electronic devices, self-assembly properties, and interactions with cell membranes. We have developed a simple method for quantitative determination of Q in their native aqueous environment. The method does not require the knowledge of exact atomic structure or make assumptions about effects of drying on charge distribution. The method is based on titration of nanoparticle dispersion with a solution of oppositely charged polyelectrolyte. The point of complete neutralization is recognized as an inflection point on the dependence of fluorescence intensity on the amount of polyelectrolyte added. Thioglycolic acid-stabilized CdTe nanoparticles 2 nm in diameter were found to carry an average Q from -2.6 to -5.5 for pH 7.5 to 10, respectively. This charge is found to be smaller than that calculated theoretically for an analogous structure (i.e., Q = -8), presumably due to adsorption of Cd(2+) ions on the stabilizer shell and on Te atoms with unsaturated valence located on the side planes of CdTe tetrahedrons.
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