1
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Prior A, Nikolopoulos LAA. Dynamics of Correlated Double-Ionization of Two-Electron Quantum Dots in Laser Fields. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1405. [PMID: 36837035 PMCID: PMC9967998 DOI: 10.3390/ma16041405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Using an ab initio, time-dependent calculational method, we study the non-linear dynamics of a two-electron quantum dot in the presence of ultrashort Thz laser pulses. The analysis of the contribution of the various partial waves to two-electron joint radial and energy distribution patterns revealed strongly correlated electron ejection channels. In the double-ionization process, regardless of the photon energy, the two-electron wave packets are born and remain concentrated until the pulse's peak; at later times, and depending on the photon energy of the field, distinctly different patterns emerge. Our calculations also showed the gradual transition of the radial and energy patterns from a single-peak to a doubly peaked structure, associated with the direct and the sequential double-ionization mechanisms, respectively.
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2
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Long J, Qiu Z, Wei J, Li D, Song X, Jin B, Zhang B. Liquid-microjet photoelectron imaging spectrometry for liquid aqueous solutions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:065108. [PMID: 34243573 DOI: 10.1063/5.0036471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 05/16/2021] [Indexed: 06/13/2023]
Abstract
A new liquid-microjet photoelectron imaging (PEI) spectrometer has been constructed that combines the liquid-microjet technique with velocity-map imaging. This novel method enables us to simultaneously measure the energy and angular distributions of the photoelectrons produced from highly volatile liquid solutions. The capability of the spectrometer has been demonstrated by recording the photoelectron image of the aqueous 2-furfural. To our knowledge, this is the first time that the PEI of liquid aqueous solutions has succeeded.
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Affiliation(s)
- Jinyou Long
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Ziheng Qiu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Jie Wei
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Duoduo Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Xinli Song
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Bing Jin
- Institute of Molecular Sciences and Engineering, Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao 266235, People's Republic of China
| | - Bing Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
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3
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Hartweg S, Garcia GA, Božanić DK, Nahon L. Condensation Effects on Electron Chiral Asymmetries in the Photoionization of Serine: From Free Molecules to Nanoparticles. J Phys Chem Lett 2021; 12:2385-2393. [PMID: 33660503 DOI: 10.1021/acs.jpclett.1c00258] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Structural changes at the molecular level, occurring at the onset of condensation, can be probed by angle-resolved valence photoelectron spectroscopy, which is inherently sensitive to the electronic structure. For larger condensed systems like aerosol particles, the observation of intrinsic angular anisotropies in photoemission (β parameters) is challenging due to the strong reduction of their magnitude by electron transport effects. Here, we use a less common, more sensitive observable in the form of the chiral asymmetry parameter to perform a comparative study of the VUV photoelectron spectroscopy and photoelectron circular dichroism (PECD) between pure gas phase enantiomers of the amino acid serine and their corresponding homochiral nanoparticles. We observe a relatively large (1%) and strongly kinetic energy-dependent asymmetry, discussed in terms of the emergence of local order and conformational changes potentially counterbalancing the loss of angular information due to electron transport scattering. This demonstrates the potential of PECD as a sensitive probe of the condensation effects from the gas phase to bulk-like chiral aerosol particles surpassing the potential of conventional photoemission observables such as β parameters.
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Affiliation(s)
- Sebastian Hartweg
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Cedex, Gif sur Yvette, France
| | - Gustavo A Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Cedex, Gif sur Yvette, France
| | - Dušan K Božanić
- Department of Radiation Chemistry and Physics, "VINČA" Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, 11001 Belgrade, Serbia
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192 Cedex, Gif sur Yvette, France
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4
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Utterback JK, Ruzicka JL, Keller HR, Pellows LM, Dukovic G. Electron Transfer from Semiconductor Nanocrystals to Redox Enzymes. Annu Rev Phys Chem 2020; 71:335-359. [PMID: 32074472 DOI: 10.1146/annurev-physchem-050317-014232] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review summarizes progress in understanding electron transfer from photoexcited nanocrystals to redox enzymes. The combination of the light-harvesting properties of nanocrystals and the catalytic properties of redox enzymes has emerged as a versatile platform to drive a variety of enzyme-catalyzed reactions with light. Transfer of a photoexcited charge from a nanocrystal to an enzyme is a critical first step for these reactions. This process has been studied in depth in systems that combine Cd-chalcogenide nanocrystals with hydrogenases. The two components can be assembled in close proximity to enable direct interfacial electron transfer or integrated with redox mediators to transport charges. Time-resolved spectroscopy and kinetic modeling have been used to measure the rates and efficiencies of the electron transfer. Electron transfer has been described within the framework of Marcus theory, providing insights into the factors that can be used to control the photochemical activity of these biohybrid systems. The range of potential applications and reactions that can be achieved using nanocrystal-enzyme systems is expanding, and numerous fundamental and practical questions remain to be addressed.
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Affiliation(s)
- James K Utterback
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , , .,Current affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA;
| | - Jesse L Ruzicka
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
| | - Helena R Keller
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, USA;
| | - Lauren M Pellows
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
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5
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Ahmed M, Kostko O. From atoms to aerosols: probing clusters and nanoparticles with synchrotron based mass spectrometry and X-ray spectroscopy. Phys Chem Chem Phys 2020; 22:2713-2737. [DOI: 10.1039/c9cp05802h] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Synchrotron radiation provides insight into spectroscopy and dynamics in clusters and nanoparticles.
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Affiliation(s)
- Musahid Ahmed
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Oleg Kostko
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
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6
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De Anda Villa M, Gaudin J, Amans D, Boudjada F, Bozek J, Evaristo Grisenti R, Lamour E, Laurens G, Macé S, Nicolas C, Papagiannouli I, Patanen M, Prigent C, Robert E, Steydli S, Trassinelli M, Vernhet D, Lévy A. Assessing the Surface Oxidation State of Free-Standing Gold Nanoparticles Produced by Laser Ablation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11859-11871. [PMID: 31453695 DOI: 10.1021/acs.langmuir.9b02159] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The surface chemistry of gold nanoparticles produced by the pulsed laser ablation in liquids method is investigated by X-ray photoelectron spectroscopy (XPS). The presence of surface oxide expected on these systems is investigated using synchrotron radiation in conditions close to their original state in solvent but free from substrate or solvent effects which could affect the interpretation of spectroscopic observations. For that purpose we performed the experiment on a controlled free-standing nanoparticle beam produced by combination of an atomizer and an aerodynamic lens system. These results are compared with those obtained by the standard situation of deposited nanoparticles on silicon substrate. An accurate analysis based on Bayesian statistics concludes that the existence of oxide in the free-standing conditions cannot be solely confirmed by the recorded core-level 4f spectra. If present, our data indicate an upper limit of 2.15 ± 0.68% of oxide. However, a higher credence to the hypothesis of its existence is brought by the structureless valence profile of the free-standing beam. Moreover, the cross-comparison with the deposited nanoparticles case clearly evidences an important misleading substrate effect. Experiment with free-standing nanoparticles is then demonstrated to be the right way to further investigate oxidation states on Au nanoparticles.
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Affiliation(s)
- Manuel De Anda Villa
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Jérôme Gaudin
- CNRS, CEA, CELIA (Centre Lasers Intenses et Applications) , Univeristy of Bordeaux , UMR5107 , F-33405 Talence , France
| | - David Amans
- Université Claude Bernard Lyon 1, UMR5306 CNRS, Institut Lumière Matière , Univeristy of Lyon , F-69622 Villeurbanne , France
| | - Fahima Boudjada
- Université Claude Bernard Lyon 1, UMR5306 CNRS, Institut Lumière Matière , Univeristy of Lyon , F-69622 Villeurbanne , France
| | - John Bozek
- L'Orme des Merisiers , Synchrotron SOLEIL , Saint-Aubin, BP 48 , F-91192 Gif-sur-Yvette Cedex , France
| | - Robert Evaristo Grisenti
- GSI Helmholtzzentrum für Schwerionenforschung GmbH , Planckstrasse 1 , 64291 Darmstadt , Germany
- Institut für Kernphysik , J. W. Goethe-Universität , Max-von-Laue-strasse 1 , 60438 Frankfurt am Main , Germany
| | - Emily Lamour
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Gaétan Laurens
- Université Claude Bernard Lyon 1, UMR5306 CNRS, Institut Lumière Matière , Univeristy of Lyon , F-69622 Villeurbanne , France
| | - Stéphane Macé
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Christophe Nicolas
- L'Orme des Merisiers , Synchrotron SOLEIL , Saint-Aubin, BP 48 , F-91192 Gif-sur-Yvette Cedex , France
| | - Irene Papagiannouli
- CNRS, CEA, CELIA (Centre Lasers Intenses et Applications) , Univeristy of Bordeaux , UMR5107 , F-33405 Talence , France
| | - Minna Patanen
- Nano and Molecular Systems Research Unit, Faculty of Science , University of Oulu , P.O. Box 3000, FI-90014 Oulu , Finland
| | - Christophe Prigent
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Emmanuel Robert
- L'Orme des Merisiers , Synchrotron SOLEIL , Saint-Aubin, BP 48 , F-91192 Gif-sur-Yvette Cedex , France
| | - Sébastien Steydli
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Martino Trassinelli
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Dominique Vernhet
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
| | - Anna Lévy
- Institut des Nanosciences de Paris , Sorbonne Université-Pierre et Marie Curie , CNRS UMR7588 , 75005 Paris , France
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7
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Jacobs MI, Xu B, Kostko O, Wiegel AA, Houle FA, Ahmed M, Wilson KR. Using Nanoparticle X-ray Spectroscopy to Probe the Formation of Reactive Chemical Gradients in Diffusion-Limited Aerosols. J Phys Chem A 2019; 123:6034-6044. [DOI: 10.1021/acs.jpca.9b04507] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Michael I. Jacobs
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Bo Xu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Oleg Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron A. Wiegel
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Frances A. Houle
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Kevin R. Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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8
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Milosavljević AR, Božanić DK, Sadhu S, Vukmirović N, Dojčilović R, Sapkota P, Huang W, Bozek J, Nicolas C, Nahon L, Ptasinska S. Electronic Properties of Free-Standing Surfactant-Capped Lead Halide Perovskite Nanocrystals Isolated in Vacuo. J Phys Chem Lett 2018; 9:3604-3611. [PMID: 29902010 DOI: 10.1021/acs.jpclett.8b01466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We report an investigation of lead halide perovskite CH3NH3PbBr3 nanocrystals and associated ligand molecules by combining several different state-of-the-art experimental techniques, including synchrotron radiation-based XPS and VUV PES of free-standing nanocrystals isolated in vacuum. By using this novel approach for perovskite materials, we could directly obtain complete band alignment to vacuum of both CH3NH3PbBr3 nanocrystals and the ligands widely used in their preparation. We discuss the possible influence of the ligand molecules to apparent perovskite properties, and we compare the electronic properties of nanocrystals to those of bulk material. The experimental results were supported by DFT calculations.
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Affiliation(s)
| | - Dušan K Božanić
- Synchrotron SOLEIL, l'Orme des Merisiers , Saint Aubin , BP48, 91192 Gif sur Yvette Cedex, France
- Vinča Institute of Nuclear Sciences , University of Belgrade , P.O. Box 522, 11001 Belgrade , Serbia
| | - Subha Sadhu
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Nenad Vukmirović
- Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade , University of Belgrade , Pregrevica 118 , 11080 Belgrade , Serbia
| | - Radovan Dojčilović
- Vinča Institute of Nuclear Sciences , University of Belgrade , P.O. Box 522, 11001 Belgrade , Serbia
| | - Pitambar Sapkota
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
- Department of Physics , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Weixin Huang
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - John Bozek
- Synchrotron SOLEIL, l'Orme des Merisiers , Saint Aubin , BP48, 91192 Gif sur Yvette Cedex, France
| | - Christophe Nicolas
- Synchrotron SOLEIL, l'Orme des Merisiers , Saint Aubin , BP48, 91192 Gif sur Yvette Cedex, France
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers , Saint Aubin , BP48, 91192 Gif sur Yvette Cedex, France
| | - Sylwia Ptasinska
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
- Department of Physics , University of Notre Dame , Notre Dame , Indiana 46556 , United States
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9
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Bachau H, Nikolopoulos LAA. Direct and Sequential Two-Photon Double Ionization of Two-Electron Quantum Dots. J Phys Chem A 2018; 122:1574-1583. [PMID: 29356525 DOI: 10.1021/acs.jpca.7b11811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work we study the double ionization yields and kinetic energy spectra of a two-electron spherical quantum dot (QD) exposed in laser fields. The theoretical description is based on an ab initio nonperturbative configuration interaction theory capable of describing the two-electron QD dynamics in THz and mid-IR ultrashort laser fields. The QD's confinement potential is approximated to have a Gaussian-like spatial dependence. We have found that significant variations of the two-electron kinetic energy patterns and two-photon double ionization yields occur as we vary the QD's size. For a given laser pulse, the double ionization yield increases by orders of magnitude when the dot size is reduced. The size of the QD determines the sequential or direct character of the two-photon double ionization process. Provided that it is energetically allowed, the sequential two-photon double ionization process, requiring minimal interelectronic correlations, becomes dominant over the direct one. In the sequential regime, the corresponding two-electron kinetic energy spectrum changes from a broadened single-peaked to a doubly peaked one. Moreover, we also have identified features in the spectrum that are distinctively different than those in its atomic counterpart.
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Affiliation(s)
- Henri Bachau
- Centre des Lasers Intenses et Applications, Université de Bordeaux-CNRS-CEA , F-33405 Talence Cedex, France
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10
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Makarov NS, Lim J, Lin Q, Lewellen JW, Moody NA, Robel I, Pietryga JM. Quantum Dot Thin-Films as Rugged, High-Performance Photocathodes. NANO LETTERS 2017; 17:2319-2327. [PMID: 28253617 DOI: 10.1021/acs.nanolett.6b05175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Typical use of colloidal quantum dots (QDs) as bright, tunable phosphors in real applications relies on engineering of their surfaces to suppress the loss of excited carriers to surface trap states or to the surrounding medium. Here, we explore the utility of QDs in an application that actually exploits their propensity toward photoionization, namely within efficient and robust photocathodes for use in next-generation electron guns. In order to establish the relevance of QD films as photocathodes, we evaluate the efficiency of electron photoemission of films of a variety of compositions in a typical electron gun configuration. By quantifying photocurrent as a function of excitation photon energy, excitation intensity and pulse duration, we establish the role of hot electrons in photoemission within the multiphoton excitation regime. We also demonstrate the effect of QD structure and film deposition methods on efficiency, which suggests numerous pathways for further enhancements. Finally, we show that QD photocathodes offer superior efficiencies relative to standard copper cathodes and are robust against degradation under ambient conditions.
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Affiliation(s)
- Nikolay S Makarov
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jaehoon Lim
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Qianglu Lin
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - John W Lewellen
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Nathan A Moody
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - István Robel
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jeffrey M Pietryga
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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11
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Ellis JL, Hickstein DD, Xiong W, Dollar F, Palm BB, Keister KE, Dorney KM, Ding C, Fan T, Wilker MB, Schnitzenbaumer KJ, Dukovic G, Jimenez JL, Kapteyn HC, Murnane MM. Materials Properties and Solvated Electron Dynamics of Isolated Nanoparticles and Nanodroplets Probed with Ultrafast Extreme Ultraviolet Beams. J Phys Chem Lett 2016; 7:609-615. [PMID: 26807653 DOI: 10.1021/acs.jpclett.5b02772] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present ultrafast photoemission measurements of isolated nanoparticles in vacuum using extreme ultraviolet (EUV) light produced through high harmonic generation. Surface-selective static EUV photoemission measurements were performed on nanoparticles with a wide array of compositions, ranging from ionic crystals to nanodroplets of organic material. We find that the total photoelectron yield varies greatly with nanoparticle composition and provides insight into material properties such as the electron mean free path and effective mass. Additionally, we conduct time-resolved photoelectron yield measurements of isolated oleylamine nanodroplets, observing that EUV photons can create solvated electrons in liquid nanodroplets. Using photoemission from a time-delayed 790 nm pulse, we observe that a solvated electron is produced in an excited state and subsequently relaxes to its ground state with a lifetime of 151 ± 31 fs. This work demonstrates that femotosecond EUV photoemission is a versatile surface-sensitive probe of the properties and ultrafast dynamics of isolated nanoparticles.
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Affiliation(s)
- Jennifer L Ellis
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Daniel D Hickstein
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Wei Xiong
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
- Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States
| | - Franklin Dollar
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Brett B Palm
- CIRES and Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - K Ellen Keister
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Kevin M Dorney
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Chengyuan Ding
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Tingting Fan
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Molly B Wilker
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Kyle J Schnitzenbaumer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Jose L Jimenez
- CIRES and Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Henry C Kapteyn
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
| | - Margaret M Murnane
- JILA-NIST and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309, United States
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12
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Hautala L, Jänkälä K, Mikkelä MH, Tchaplyguine M, Huttula M. Surface site coordination dependent responses resolved in free clusters: applications for neutral sub-nanometer cluster studies. Phys Chem Chem Phys 2015; 17:7012-22. [PMID: 25684564 DOI: 10.1039/c4cp05422a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper we demonstrate how surface site specific experimental information can be obtained from free low nanometer scale clusters using photoelectron spectroscopy utilising synchrotron radiation. In addition, we show how it can be used to gain insight into the geometry and surface structure of the clusters. The present experiments were conducted on alkali metal halides, RbCl and CsCl, which were chosen as advantageous test cases due to their simple electronic and geometric structures. These heavy alkali metal salts provide additional clarity since the surface and bulk responses can be separated, which is not the case for clusters of lighter alkali metal salts. Computational chemical shift calculations and simple alkali halide cluster size modelling were used to interpret the experimental results.
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Affiliation(s)
- Lauri Hautala
- Department of Physics, University of Oulu, P. O. Box 3000, 90014 Oulu, Finland.
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13
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In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection. Sci Rep 2015; 5:15696. [PMID: 26498694 PMCID: PMC4620506 DOI: 10.1038/srep15696] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 09/15/2015] [Indexed: 01/28/2023] Open
Abstract
The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed.
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14
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Ehamparam R, Pavlopoulos NG, Liao MW, Hill LJ, Armstrong NR, Pyun J, Saavedra SS. Band Edge Energetics of Heterostructured Nanorods: Photoemission Spectroscopy and Waveguide Spectroelectrochemistry of Au-Tipped CdSe Nanorod Monolayers. ACS NANO 2015; 9:8786-800. [PMID: 26291717 DOI: 10.1021/acsnano.5b01720] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Conduction and valence band energies (ECB, EVB) for CdSe nanorods (NRs) functionalized with Au nanoparticle (NP) tips are reported here, referenced to the vacuum scale. We use (a) UV photoemission spectroscopy (UPS) to measure EVB for NR films, utilizing advanced approaches to secondary electron background correction, satellite removal to enhance spectral contrast, and correction for shifts in local vacuum levels; and (b) waveguide-based spectroelectrochemistry to measure ECB from onset potentials for electron injection into NR films tethered to ITO. For untipped CdSe NRs, both approaches show EVB = 5.9-6.1 eV and ECB = 4.1-4.3 eV. Addition of Au tips alters the NR band edge energies and introduces midgap states, in ways that are predicted to influence the efficiency of these nanomaterials as photoelectrocatalysts. UPS results show that Au tipping shifts EVB closer to vacuum by up to 0.4 eV, shifts the apparent Fermi energy toward the middle of the band gap, and introduces additional states above EVB. Spectroelectrochemical results confirm these trends: Au tipping shifts ECB closer to vacuum, by 0.4-0.6 eV, and introduces midgap states below ECB, which are assigned as metal-semiconductor interface (MSI) states. Characterization of these band edge energies and understanding the origins of MSI states is needed to design energy conversion systems with proper band alignment between the light absorbing NR, the NP catalyst, and solution electron donors and acceptors. The complementary characterization protocols presented here should be applicable to a wide variety of thin films of heterogeneous photoactive nanomaterials, aiding in the identification of the most promising material combinations for photoelectrochemical energy conversion.
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Affiliation(s)
- Ramanan Ehamparam
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Nicholas G Pavlopoulos
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Michael W Liao
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Lawrence J Hill
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Neal R Armstrong
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Jeffrey Pyun
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
- World Class University Program for Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering, Seoul National University , Seoul 151-744, Korea
| | - S Scott Saavedra
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
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15
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Ellis JL, Hickstein DD, Schnitzenbaumer KJ, Wilker MB, Palm BB, Jimenez JL, Dukovic G, Kapteyn HC, Murnane MM, Xiong W. Solvents effects on charge transfer from quantum dots. J Am Chem Soc 2015; 137:3759-62. [PMID: 25751367 DOI: 10.1021/jacs.5b00463] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To predict and understand the performance of nanodevices in different environments, the influence of the solvent must be explicitly understood. In this Communication, this important but largely unexplored question is addressed through a comparison of quantum dot charge transfer processes occurring in both liquid phase and in vacuum. By comparing solution phase transient absorption spectroscopy and gas-phase photoelectron spectroscopy, we show that hexane, a common nonpolar solvent for quantum dots, has negligible influence on charge transfer dynamics. Our experimental results, supported by insights from theory, indicate that the reorganization energy of nonpolar solvents plays a minimal role in the energy landscape of charge transfer in quantum dot devices. Thus, this study demonstrates that measurements conducted in nonpolar solvents can indeed provide insight into nanodevice performance in a wide variety of environments.
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Affiliation(s)
- Jennifer L Ellis
- †Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
| | - Daniel D Hickstein
- †Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
| | - Kyle J Schnitzenbaumer
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Molly B Wilker
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Brett B Palm
- §Department of Chemistry and Biochemistry and CIRES, University of Colorado, Boulder, Colorado 80309, United States
| | - Jose L Jimenez
- §Department of Chemistry and Biochemistry and CIRES, University of Colorado, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Henry C Kapteyn
- †Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
| | - Margaret M Murnane
- †Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
| | - Wei Xiong
- †Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
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16
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Howder CR, Long BA, Bell DM, Furakawa KH, Johnson RC, Fang Z, Anderson SL. Photoluminescence of charged CdSe/ZnS quantum dots in the gas phase: effects of charge and heating on absorption and emission probabilities. ACS NANO 2014; 8:12534-12548. [PMID: 25427008 DOI: 10.1021/nn505374d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Gas phase spectral measurements for CdSe/ZnS core/shell nanocrystal quantum dots (QDs) before and after heating with both infrared (CO2) and visible lasers are reported. As-trapped QDs are spectrally similar to the same QDs in solution; however their photoluminescence (PL) intensities are very low, at least partly due to low absorption cross sections. After heating, the PL intensities brighten by factors ranging from ∼4 to 1800 depending on the QD size and pump laser wavelength. The emission spectra no longer resemble solution spectra and are similar, regardless of the QD diameter. Emission extends from the pump laser wavelength into the near-IR, with strong emission features above the band gap energy, between 645 and 775 nm, and in the near-infrared. Emission spectra from brightened QD ensembles, single QD aggregates, and single QD monomers are similar, showing that even single QDs support PL from a wide variety of states. The heating and cooling processes for QDs in this environment are analyzed, providing limits on the magnitudes of the absorption cross sections before and after thermal brightening. A model, based on absorption bleaching by extra electrons in the conduction band, appears to account for the changes in absorption and emission behavior induced by charging and heating.
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Affiliation(s)
- Collin R Howder
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
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17
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Miron C, Patanen M. Synchrotron-radiation-based soft X-ray electron spectroscopy applied to structural and chemical characterization of isolated species, from molecules to nanoparticles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:7911-7916. [PMID: 24902675 DOI: 10.1002/adma.201304837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 01/27/2014] [Indexed: 06/03/2023]
Abstract
With its extended tunability from the IR to hard X-rays and the exceptional spectral brightness offered by the 3rd generation storage rings, synchrotron radiation (SR) is an invaluable investigation tool. Major methodological developments are now available, and are applied to simple, isolated atoms and molecules (which can be often modeled ab initio) and are then extended to the investigation of more and more complex species, up to soft and hard condensed matter. The present article highlights, with a few examples, the most recent achievements in SR-based soft X-ray electron spectroscopy applied to the structural characterization of isolated species of increasing complexity, from molecules and clusters to nanoparticles. Special attention is devoted to very high resolution studies of single molecules revealing electron diffraction and interference effects, as well as detailed information about their potential energy surfaces. These achievements are only possible based on the new opportunities offered by the most advanced SR facilities.
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Affiliation(s)
- Catalin Miron
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192, Gif-sur-Yvette Cedex, France
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18
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Sublemontier O, Nicolas C, Aureau D, Patanen M, Kintz H, Liu X, Gaveau MA, Le Garrec JL, Robert E, Barreda FA, Etcheberry A, Reynaud C, Mitchell JB, Miron C. X-ray Photoelectron Spectroscopy of Isolated Nanoparticles. J Phys Chem Lett 2014; 5:3399-403. [PMID: 26278452 DOI: 10.1021/jz501532c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
X-ray photoelectron spectroscopy (XPS) is a very efficient and still progressing surface analysis technique. However, when applied to nano-objects, this technique faces drawbacks due to interactions with the substrate and sample charging effects. We present a new experimental approach to XPS based on coupling soft X-ray synchrotron radiation with an in-vacuum beam of free nanoparticles, focused by an aerodynamic lens system. The structure of the Si/SiO2 interface was probed without any substrate interaction or charging effects for silicon nanocrystals previously oxidized in ambient air. Complete characterization of the surface was obtained. The Si 2p core level spectrum reveals a nonabrupt interface.
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Affiliation(s)
| | - Christophe Nicolas
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Damien Aureau
- §Institut Lavoisier de Versailles, Université Versailles-St Quentin, UMR CNRS 8180, 78035 Versailles, France
| | - Minna Patanen
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Harold Kintz
- †CEA/IRAMIS/Laboratoire Francis Perrin, URA 2453, 91191 Gif-sur-Yvette, France
| | - Xiaojing Liu
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Marc-André Gaveau
- †CEA/IRAMIS/Laboratoire Francis Perrin, URA 2453, 91191 Gif-sur-Yvette, France
| | - Jean-Luc Le Garrec
- ∥Institut de Physique de Rennes, Université Rennes 1, 35042 Rennes, France
| | - Emmanuel Robert
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Flory-Anne Barreda
- †CEA/IRAMIS/Laboratoire Francis Perrin, URA 2453, 91191 Gif-sur-Yvette, France
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Arnaud Etcheberry
- §Institut Lavoisier de Versailles, Université Versailles-St Quentin, UMR CNRS 8180, 78035 Versailles, France
| | - Cécile Reynaud
- †CEA/IRAMIS/Laboratoire Francis Perrin, URA 2453, 91191 Gif-sur-Yvette, France
| | - James B Mitchell
- ∥Institut de Physique de Rennes, Université Rennes 1, 35042 Rennes, France
| | - Catalin Miron
- ‡Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
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19
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Hickstein DD, Dollar F, Ellis JL, Schnitzenbaumer KJ, Keister KE, Petrov GM, Ding C, Palm BB, Gaffney JA, Foord ME, Libby SB, Dukovic G, Jimenez JL, Kapteyn HC, Murnane MM, Xiong W. Mapping nanoscale absorption of femtosecond laser pulses using plasma explosion imaging. ACS NANO 2014; 8:8810-8. [PMID: 25100104 DOI: 10.1021/nn503199v] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We make direct observations of localized light absorption in a single nanostructure irradiated by a strong femtosecond laser field, by developing and applying a technique that we refer to as plasma explosion imaging. By imaging the photoion momentum distribution resulting from plasma formation in a laser-irradiated nanostructure, we map the spatial location of the highly localized plasma and thereby image the nanoscale light absorption. Our method probes individual, isolated nanoparticles in vacuum, which allows us to observe how small variations in the composition, shape, and orientation of the nanostructures lead to vastly different light absorption. Here, we study four different nanoparticle samples with overall dimensions of ∼100 nm and find that each sample exhibits distinct light absorption mechanisms despite their similar size. Specifically, we observe subwavelength focusing in single NaCl crystals, symmetric absorption in TiO2 aggregates, surface enhancement in dielectric particles containing a single gold nanoparticle, and interparticle hot spots in dielectric particles containing multiple smaller gold nanoparticles. These observations demonstrate how plasma explosion imaging directly reveals the diverse ways in which nanoparticles respond to strong laser fields, a process that is notoriously challenging to model because of the rapid evolution of materials properties that takes place on the femtosecond time scale as a solid nanostructure is transformed into a dense plasma.
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Affiliation(s)
- Daniel D Hickstein
- JILA and Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
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20
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Mangum BD, Sampat S, Ghosh Y, Hollingsworth JA, Htoon H, Malko AV. Influence of the core size on biexciton quantum yield of giant CdSe/CdS nanocrystals. NANOSCALE 2014; 6:3712-3720. [PMID: 24569861 DOI: 10.1039/c3nr06558h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a systematic study of photoluminescence (PL) emission intensity and biexciton (BX) quantum yields (QYBX) in individual "giant" CdSe/CdS nanocrystals (g-NCs) as a function of g-NC core size and shell thickness. We show that g-NC core size significantly affects QYBX and can be utilized as an effective tuning parameter towards higher QYBX while keeping the total volume of the g-NC constant. Specifically, we observe that small-core (2.2 nm diameter) CdSe/CdS NCs with a volume of ∼200 nm(3) (shell comprises 4 CdS monolayers) show very low average and maximum QYBX's of ∼3 and 7%, respectively. In contrast, same-volume medium-core (3 nm diameter) NCs afford higher average values of ∼10%, while QYBX's of ∼30% are achieved for same-volume large-core (5.5 nm diameter) CdSe/CdS NCs, with some approaching ∼80%. These observations underline the influence of the g-NC core size on the evolution of PL emissive states in multi-shell NCs. Moreover, our study also reveals that the use of long anneal times in the growth of CdS shells plays a critical role in achieving high QYBX.
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Affiliation(s)
- Benjamin D Mangum
- Materials Physics and Applications Division, Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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21
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Bell DM, Howder CR, Johnson RC, Anderson SL. Single CdSe/ZnS nanocrystals in an ion trap: charge and mass determination and photophysics evolution with changing mass, charge, and temperature. ACS NANO 2014; 8:2387-2398. [PMID: 24410129 DOI: 10.1021/nn405920k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report measurements of fluorescence intermittency (blinking) and spectral behavior for single semiconductor nanocrystal quantum dots (QDs) isolated in the gas phase and discuss the effects on fluorescence of the QD charge state and heating to the point of sublimation. Core-shell CdSe/ZnS QDs were trapped in a quadrupole ion trap and detected by laser-induced fluorescence. The mass (M) and charge (Q) were determined nondestructively, and both were followed continuously over the course of hours or days. Emission spectra of the trapped QDs are significantly red-shifted relative to the solution-phase emission from the same particles. The temperature of the trapped QDs is determined by the balance between laser heating and collisional cooling and thermal emission, and it is possible to heat the particles to remove ligands or to the point of sublimation. QDs are observed to be emissive during sublimation, for up to 85% mass loss, with emission intensity roughly proportional to the surface area. Eventually, the fluorescence quantum yield drops suddenly, and the QDs begin to blink. The method used is versatile and will allow studies of quantum dot optical properties as a function of size, ligand removal, heating, surface oxidation, and other manipulations, where these properties are continuously correlated with the mass and charge.
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Affiliation(s)
- David M Bell
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
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22
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Hickstein DD, Dollar F, Gaffney JA, Foord ME, Petrov GM, Palm BB, Keister KE, Ellis JL, Ding C, Libby SB, Jimenez JL, Kapteyn HC, Murnane MM, Xiong W. Observation and control of shock waves in individual nanoplasmas. PHYSICAL REVIEW LETTERS 2014; 112:115004. [PMID: 24702383 DOI: 10.1103/physrevlett.112.115004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Indexed: 05/20/2023]
Abstract
Using an apparatus that images the momentum distribution of individual, isolated 100-nm-scale plasmas, we make the first experimental observation of shock waves in nanoplasmas. We demonstrate that the introduction of a heating pulse prior to the main laser pulse increases the intensity of the shock wave, producing a strong burst of quasimonoenergetic ions with an energy spread of less than 15%. Numerical hydrodynamic calculations confirm the appearance of accelerating shock waves and provide a mechanism for the generation and control of these shock waves. This observation of distinct shock waves in dense plasmas enables the control, study, and exploitation of nanoscale shock phenomena with tabletop-scale lasers.
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Affiliation(s)
- Daniel D Hickstein
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Franklin Dollar
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Jim A Gaffney
- Physics Division, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Mark E Foord
- Physics Division, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - George M Petrov
- Plasma Physics Division, Naval Research Lab, Washington, District of Columbia 20375, USA
| | - Brett B Palm
- Department of Chemistry and Biochemistry and CIRES, University of Colorado, Boulder, Colorado 80309, USA
| | - K Ellen Keister
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Jennifer L Ellis
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Chengyuan Ding
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Stephen B Libby
- Physics Division, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Jose L Jimenez
- Department of Chemistry and Biochemistry and CIRES, University of Colorado, Boulder, Colorado 80309, USA
| | - Henry C Kapteyn
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Margaret M Murnane
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Wei Xiong
- Department of Physics, University of Colorado and JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
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23
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Zhao MX, Li Y, Zeng EZ, Wang CJ. The application of CdSe quantum dots with multicolor emission as fluorescent probes for cell labeling. Chem Asian J 2014; 9:1349-55. [PMID: 24616373 DOI: 10.1002/asia.201301692] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Indexed: 12/16/2022]
Abstract
Herein, highly luminescent CdSe quantum dots (QDs) with emissions from the blue to the red region of visible light were synthesized by using a simple method. The emission range of the CdSe QDs could be tuned from λ=503 to 606 nm by controlling the size of the CdSe QDs. Two amino acids, L-tryptophan (L-Trp) and L-arginine (L-Arg), were used as coating agents. The quantum yield (QY) of CdSe QDs (green color) with an optimized thickness could reach up to 52 %. The structures and compositions of QDs were examined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Optical properties were studied by using UV/Vis and photoluminescence (PL) spectroscopy and a comparison was made between uncoated and coated CdSe QDs. The amino acid-modified β-cyclodextrin (CD)-coated CdSe QDs presented lower cytotoxicity to cells for 48 h. Furthermore, amino acid-modified β-CD-coated green CdSe QDs in HepG2 cells were assessed by using confocal laser scanning fluorescence microscopy. The results showed that amino acid-modified β-CD-coated green CdSe QDs could enter tumor cells efficiently and indicated that biomolecule-coated QDs could be used as a potential fluorescent probe.
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Affiliation(s)
- Mei-Xia Zhao
- Key Laboratory of Natural Medicine and Immune Engineering, Henan University, Kaifeng 475004 (China), Fax: (+86) 371-22864665.
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24
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Katsiev K, Ip AH, Fischer A, Tanabe I, Zhang X, Kirmani AR, Voznyy O, Rollny LR, Chou KW, Thon SM, Carey GH, Cui X, Amassian A, Dowben P, Sargent EH, Bakr OM. The complete in-gap electronic structure of colloidal quantum dot solids and its correlation with electronic transport and photovoltaic performance. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:937-42. [PMID: 24243769 DOI: 10.1002/adma.201304166] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/30/2013] [Indexed: 05/25/2023]
Abstract
The direct observation of the complete electronic band structure of a family of PbS CQD solids via photoelectron spectroscopy is reported. We investigate how materials processing strategies, such as the latest passivation methods that produce record-performance photovoltaics, achieve their performance advances. Halide passivated films show a drastic reduction in states in the midgap, contributing to a marked improvement in the device performance.
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Affiliation(s)
- Khabiboulakh Katsiev
- Division of Physical Sciences and Engineering, Solar and Photovoltaic Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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