1
|
Wen H, Li J, Zhang Q, Inose T, Peeters W, Fortuni B, Asakawa H, Masuhara A, Hirai K, Toyouchi S, Fujita Y, Uji-I H. Length-Controllable Gold-Coated Silver Nanowire Probes for High AFM-TERS Scattering Activity. NANO LETTERS 2023; 23:1615-1621. [PMID: 36484776 DOI: 10.1021/acs.nanolett.2c03985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Tip-enhanced Raman scattering (TERS) microscopy is an advanced technique for investigation at the nanoscale that provides topographic and chemical information simultaneously. The TERS probe plays a crucial role in the microscopic performance. In the recent past, the development of silver nanowire (AgNW) based TERS probes solved the main tip fabrication issues, such as low mechanical strength and reproducibility. However, this fabrication method still suffers from low control of the protruded length of the AgNW. In this work, a simple water-air interface electrocutting method is proposed to achieve wide controllability of the length. This water cutting method was combined with a succedent Au coating on the AgNW surface, and the probe achieved an up to 100× higher enhancement factor (EF) and a 2× smaller spatial resolution compared to pristine AgNW. Thanks to this excellent EF, the water-cut Au-coated AgNW probes were found to possess high TERS activity even in the nongap mode, enabling broad applications.
Collapse
Affiliation(s)
- Han Wen
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan
| | - Jiangtao Li
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan
| | - Qiang Zhang
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan
| | - Tomoko Inose
- Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto, Kyoto 606-8501, Japan
| | - Wannes Peeters
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Beatrice Fortuni
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Hitoshi Asakawa
- Nanomaterials Research Institute (NanoMaRi), Graduate School of Natural Science and Technology, and Nano Life Science Institute (NanoLSI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Akito Masuhara
- Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| | - Kenji Hirai
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan
| | - Shuichi Toyouchi
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
- Department of Applied Chemistry, College of Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yasuhiko Fujita
- Toray Research Center, Inc., Sonoyama 3-3-7, Otsu, Shiga 520-8567, Japan
| | - Hiroshi Uji-I
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan
- Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto, Kyoto 606-8501, Japan
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| |
Collapse
|
2
|
Wen H, Inose T, Hirai K, Akashi T, Sugioka S, Li J, Peeters W, Fron E, Fortuni B, Nakata Y, Rocha S, Toyouchi S, Fujita Y, Uji-I H. Gold-coated silver nanowires for long lifetime AFM-TERS probes. NANOSCALE 2022; 14:5439-5446. [PMID: 35322821 DOI: 10.1039/d1nr07833j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Tip-enhanced Raman scattering (TERS) microscopy is an advanced technique for investigation at the nanoscale because of its excellent properties, such as its label-free functionality, non-invasiveness, and ability to simultaneously provide topographic and chemical information. The probe plays a crucial role in TERS technique performance. Widely used AFM-TERS probes fabricated with metal deposition suffer from relatively low reproductivity as well as limited mapping and storage lifetime. To solve the reproducibility issue, silver nanowire (AgNW)-based TERS probes were developed, which, thanks to the high homogeneity of the liquid-phase synthesis of AgNW, can achieve high TERS performance with excellent probe reproductivity, but still present short lifetime due to probe oxidation. In this work, a simple Au coating method is proposed to overcome the limited lifetime and improve the performance of the AgNW-based TERS probe. For the Au-coating, different [Au]/[Ag] molar ratios were investigated. The TERS performance was evaluated in terms of changes in the enhancement factor (EF) and signal-to-noise ratio through multiple mappings and the storage lifetime in air. The Au-coated AgNWs exhibited higher EF than pristine AgNWs and galvanically replaced AgNWs with no remarkable difference between the two molar ratios tested. However, for longer scanning time and multiple mappings, the probes obtained with low Au concentration showed much longer-term stability and maintained a high EF. Furthermore, the Au-coated AgNW probes were found to possess a longer storage lifetime in air, allowing for long and multiple TERS mappings with one single probe.
Collapse
Affiliation(s)
- Han Wen
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
| | - Tomoko Inose
- Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kenji Hirai
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
| | - Taiki Akashi
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
| | - Shoji Sugioka
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
| | - Jiangtao Li
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
| | - Wannes Peeters
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Eduard Fron
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Beatrice Fortuni
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Yoshihiko Nakata
- Toray Research Center, Inc., Sonoyama 3-3-7, Otsu 520-8567, Shiga, Japan
| | - Susana Rocha
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Shuichi Toyouchi
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Yasuhiko Fujita
- Toray Research Center, Inc., Sonoyama 3-3-7, Otsu 520-8567, Shiga, Japan
| | - Hiroshi Uji-I
- Research Institute for Electronic Science (RIES) and Division of Information Science and Technology, Graduate School of Information Science and Technology, Hokkaido University, N20W10, Sapporo, Hokkaido 001-0020, Japan.
- Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| |
Collapse
|
3
|
Stutz EZ, Escobar Steinvall S, Litvinchuk AP, Leran JB, Zamani M, Paul R, Fontcuberta I Morral A, Dimitrievska M. Raman spectroscopy and lattice dynamics calculations of tetragonally-structured single crystal zinc phosphide (Zn 3P 2) nanowires. NANOTECHNOLOGY 2021; 32:085704. [PMID: 33171447 DOI: 10.1088/1361-6528/abc91b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Earth-abundant and low-cost semiconductors, such as zinc phosphide (Zn3P2), are promising candidates for the next generation photovoltaic applications. However, synthesis on commercially available substrates, which favors the formation of defects, and controllable doping are challenging drawbacks that restrain device performance. Better assessment of relevant properties such as structure, crystal quality and defects will allow faster advancement of Zn3P2, and in this sense, Raman spectroscopy can play an invaluable role. In order to provide a complete Raman spectrum reference of Zn3P2, this work presents a comprehensive analysis of vibrational properties of tetragonally-structured Zn3P2 (space group P42/nmc) nanowires, from both experimental and theoretical perspectives. Low-temperature, high-resolution Raman polarization measurements have been performed on single-crystalline nanowires. Different polarization configurations have allowed selective enhancement of A1g, B1g and Eg Raman modes, while B2g modes were identified from complementary unpolarized Raman measurements. Simultaneous deconvolution of all Raman spectra with Lorentzian curves has allowed identification of 33 peaks which have been assigned to 34 (8 A1g + 9 B1g + 3 B2g + 14 Eg) out of the 39 theoretically predicted eigenmodes. The experimental results are in good agreement with the vibrational frequencies that have been computed by first-principles calculations based on density functional theory. Three separate regions were observed in the phonon dispersion diagram: (i) low-frequency region (<210 cm-1) which is dominated by Zn-related vibrations, (ii) intermediate region (210-225 cm-1) which represents a true phonon gap with no observed vibrations, and (iii) high-frequency region (>225 cm-1) which is attributed to primarily P-related vibrations. The analysis of vibrational patterns has shown that non-degenerate modes involve mostly atomic motion along the long crystal axis (c-axis), while degenerate modes correspond primarily to in-plane vibrations, perpendicular to the long c-axis. These results provide a detailed reference for identification of the tetragonal Zn3P2 phase and can be used for building Raman based methodologies for effective defect screening of bulk materials and films, which might contain structural inhomogeneities.
Collapse
Affiliation(s)
- Elias Z Stutz
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Simon Escobar Steinvall
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Alexander P Litvinchuk
- Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204-5002, United States of America
| | - Jean-Baptiste Leran
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Mahdi Zamani
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Rajrupa Paul
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Anna Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Mirjana Dimitrievska
- Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| |
Collapse
|
4
|
Ma X, Zhu Y, Yu N, Kim S, Liu Q, Apontti L, Xu D, Yan R, Liu M. Toward High-Contrast Atomic Force Microscopy-Tip-Enhanced Raman Spectroscopy Imaging: Nanoantenna-Mediated Remote-Excitation on Sharp-Tip Silver Nanowire Probes. NANO LETTERS 2019; 19:100-107. [PMID: 30512954 DOI: 10.1021/acs.nanolett.8b03399] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The tip-enhanced Raman spectroscopy (TERS) imaging technique is designed to provide correlated morphological and chemical information with a nanoscale spatial resolution by utilizing the plasmonic resonance supported by metallic nanostructures at the tip apex of a scanning probe. However, limited by the scattering cross sections of these nanostructures, only a small fraction of the incident light can be coupled to the plasmonic resonance to generate Raman signals. The uncoupled light then directly excites background spectra with a diffraction-limited resolution, which becomes the background noise that often blurs the TERS image. Here, we demonstrate how this problem can be solved by physically separating the light excitation region from the Raman signal generation region on the scanning probe. The remote-excitation TERS (RE-TERS) probe, which can be fabricated with a facile, robust and reproducible method, utilizes silver nanoparticles as nanoantennas to mediate the coupling of free-space excitation light to propagating surface plasmon polaritons (SPPs) in a sharp-tip silver nanowire to excite Raman signals remotely. With this RE-TERS probe, a 10 nm spatial resolution was demonstrated on a single-walled carbon nanotube sample, and the strain distribution in a monolayer molybdenum disulfide (MoS2) was mapped.
Collapse
|
5
|
Deckert-Gaudig T, Taguchi A, Kawata S, Deckert V. Tip-enhanced Raman spectroscopy - from early developments to recent advances. Chem Soc Rev 2018. [PMID: 28640306 DOI: 10.1039/c7cs00209b] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An analytical technique operating at the nanoscale must be flexible regarding variable experimental conditions while ideally also being highly specific, extremely sensitive, and spatially confined. In this respect, tip-enhanced Raman scattering (TERS) has been demonstrated to be ideally suited to, e.g., elucidating chemical reaction mechanisms, determining the distribution of components and identifying and localizing specific molecular structures at the nanometre scale. TERS combines the specificity of Raman spectroscopy with the high spatial resolution of scanning probe microscopies by utilizing plasmonic nanostructures to confine the incident electromagnetic field and increase it by many orders of magnitude. Consequently, molecular structure information in the optical near field that is inaccessible to other optical microscopy methods can be obtained. In this general review, the development of this still-young technique, from early experiments to recent achievements concerning inorganic, organic, and biological materials, is addressed. Accordingly, the technical developments necessary for stable and reliable AFM- and STM-based TERS experiments, together with the specific properties of the instruments under different conditions, are reviewed. The review also highlights selected experiments illustrating the capabilities of this emerging technique, the number of users of which has steadily increased since its inception in 2000. Finally, an assessment of the frontiers and new concepts of TERS, which aim towards rendering it a general and widely applicable technique that combines the highest possible lateral resolution and extreme sensitivity, is provided.
Collapse
|
6
|
Milekhin AG, Rahaman M, Rodyakina EE, Latyshev AV, Dzhagan VM, Zahn DRT. Giant gap-plasmon tip-enhanced Raman scattering of MoS 2 monolayers on Au nanocluster arrays. NANOSCALE 2018; 10:2755-2763. [PMID: 29308796 DOI: 10.1039/c7nr06640f] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this article, we present the results of a gap-plasmon tip-enhanced Raman scattering study of MoS2 monolayers deposited on a periodic array of Au nanostructures on a silicon substrate forming a two dimensional (2D) crystal/plasmonic heterostructure. We observe a giant Raman enhancement of the phonon modes in the MoS2 monolayer located in the plasmonic gap between the Au tip apex and Au nanoclusters. Tip-enhanced Raman mapping allows us to determine the gap-plasmon field distribution responsible for the formation of hot spots. These hot spots provide an unprecedented giant Raman enhancement of 5.6 × 108 and a spatial resolution as small as 2.3 nm under ambient conditions. Moreover, due to strong hot electron doping in the order of 1.8 × 1013 cm-2, we observe a structural change of MoS2 from the 2H to the 1T phase. Owing to the very good spatial resolution, we are able to spatially resolve those doping sites. To the best of our knowledge, this is the first time reporting of such a phenomenon with nm spatial resolution. Our results will open the perspectives of optical diagnostics with nanometer resolution for many other 2D materials.
Collapse
Affiliation(s)
- Alexander G Milekhin
- Rzhanov Institute of Semiconductor Physics RAS, Lavrentiev Ave. 13, 630090, Novosibirsk, Russia.
| | | | | | | | | | | |
Collapse
|
7
|
Mochizuki M, Lkhamsuren G, Suthiwanich K, Mondarte EA, Yano TA, Hara M, Hayashi T. Damage-free tip-enhanced Raman spectroscopy for heat-sensitive materials. NANOSCALE 2017; 9:10715-10720. [PMID: 28681893 DOI: 10.1039/c7nr02398g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We report a method to establish experimental conditions for tip-enhanced Raman spectroscopy (TERS) with low thermal and mechanical damage to samples. In this method, we monitor the thermal desorption of thiol molecules from a gold-coated probe of an atomic force microscope (AFM) via TERS spectra. Temperatures for desorption of thiol molecules (60-100 °C) from gold surfaces cover the temperature range for degradation of heat-sensitive biomaterials (e.g. proteins). By monitoring the desorption of the thiols on the probe, we can estimate the power of an excitation laser for the samples to reach their critical temperatures for thermal degradation. Furthermore, we also found that an active oscillation of AFM cantilevers significantly promotes the heat transfer from the probe to the surrounding medium. This enables us to employ a higher power density of the excitation laser, resulting in a stronger Raman signal compared with the signal obtained with a contact mode. We propose that this combinatory method is effective in acquiring strong TERS signals while suppressing thermal and mechanical damage to soft and heat-sensitive samples.
Collapse
Affiliation(s)
- Masahito Mochizuki
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502, Japan.
| | | | | | | | | | | | | |
Collapse
|
8
|
Kawata S, Ichimura T, Taguchi A, Kumamoto Y. Nano-Raman Scattering Microscopy: Resolution and Enhancement. Chem Rev 2017; 117:4983-5001. [PMID: 28337915 DOI: 10.1021/acs.chemrev.6b00560] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Raman scattering microscopy is becoming one of the hot topics in analytical microscopy as a tool for analyzing advanced nanomaterials, such as biomolecules in a live cell for the study of cellular dynamics, semiconductor devices for characterizing strain distribution and contamination, and nanocarbons and nano-2D materials. In this paper, we review the recent progress in the development of Raman scattering microscopy from the viewpoint of spatial resolution and scattering efficiency. To overcome the extremely small cross section of Raman scattering, we discuss three approaches for the enhancement of scattering efficiency and show that the scattering enhancement synergistically increases the spatial resolution. We discuss the mechanisms of tip-enhanced Raman scattering, deep-UV resonant Raman scattering, and coherent nonlinear Raman scattering for micro- and nanoscope applications. The combinations of these three approaches are also shown as nanometer-resolution Raman scattering microscopy. The critical issues of the structures, materials, and reproducibility of tips and three-dimensionality for TERS; photodegradation for resonant Raman scattering; and laser availability for coherent nonlinear Raman scattering are also discussed.
Collapse
Affiliation(s)
- Satoshi Kawata
- Department of Applied Physics, Osaka University , Osaka 565-0871, Japan
| | - Taro Ichimura
- Quantitative Biology Center, RIKEN , Osaka 565-0874, Japan
| | - Atsushi Taguchi
- Department of Applied Physics, Osaka University , Osaka 565-0871, Japan
| | - Yasuaki Kumamoto
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine , Kyoto 602-8566, Japan
| |
Collapse
|
9
|
|
10
|
Abstract
Tuberculosis (TB), caused byMycobacterium tuberculosis(M.tb.), is one of the most prevalent and serious infectious diseases worldwide with an estimated annual global mortality of 1.4 million in 2010.
Collapse
Affiliation(s)
- Saurabh K. Srivastava
- Plant Research International
- Wageningen UR
- 6708 PB Wageningen
- The Netherlands
- Laboratory of Organic Chemistry
| | - Cees J. M. van Rijn
- Laboratory of Organic Chemistry
- Wageningen UR
- 6703 HB Wageningen
- The Netherlands
| | - Maarten A. Jongsma
- Plant Research International
- Wageningen UR
- 6708 PB Wageningen
- The Netherlands
| |
Collapse
|
11
|
Langelüddecke L, Singh P, Deckert V. Exploring the Nanoscale: Fifteen Years of Tip-Enhanced Raman Spectroscopy. APPLIED SPECTROSCOPY 2015; 69:1357-71. [PMID: 26554759 DOI: 10.1366/15-08014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Spectroscopic methods with high spatial resolution are essential to understand the physical and chemical properties of nanoscale materials including biological and chemical materials. Tip-enhanced Raman spectroscopy (TERS) is a combination of surface-enhanced Raman spectroscopy (SERS) and scanning probe microscopy (SPM), which can provide high-resolution topographic and spectral information simultaneously below the diffraction limit of light. Even examples of sub-nanometer resolution have been demonstrated. This review intends to give an introduction to TERS, focusing on its basic principle and the experimental setup, the strengths followed by recent applications, developments, and perspectives in this field.
Collapse
Affiliation(s)
- Lucas Langelüddecke
- Institute of Physical Chemistry and Abbe Center of Photonics, University of Jena, Helmholtzweg 4, D-07743 Jena, Germany
| | | | | |
Collapse
|
12
|
Sheremet E, Milekhin AG, Rodriguez RD, Weiss T, Nesterov M, Rodyakina EE, Gordan OD, Sveshnikova LL, Duda TA, Gridchin VA, Dzhagan VM, Hietschold M, Zahn DRT. Surface- and tip-enhanced resonant Raman scattering from CdSe nanocrystals. Phys Chem Chem Phys 2015; 17:21198-203. [PMID: 25566587 DOI: 10.1039/c4cp05087h] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Surface- and tip-enhanced resonant Raman scattering (resonant SERS and TERS) by optical phonons in a monolayer of CdSe quantum dots (QDs) is demonstrated. The SERS enhancement was achieved by employing plasmonically active substrates consisting of gold arrays with varying nanocluster diameters prepared by electron-beam lithography. The magnitude of the SERS enhancement depends on the localized surface plasmon resonance (LSPR) energy, which is determined by the structural parameters. The LSPR positions as a function of nanocluster diameter were experimentally determined from spectroscopic micro-ellipsometry, and compared to numerical simulations showing good qualitative agreement. The monolayer of CdSe QDs was deposited by the Langmuir-Blodgett-based technique on the SERS substrates. By tuning the excitation energy close to the band gap of the CdSe QDs and to the LSPR energy, resonant SERS by longitudinal optical (LO) phonons of CdSe QDs was realized. A SERS enhancement factor of 2 × 10(3) was achieved. This allowed the detection of higher order LO modes of CdSe QDs, evidencing the high crystalline quality of QDs. The dependence of LO phonon mode intensity on the size of Au nanoclusters reveals a resonant character, suggesting that the electromagnetic mechanism of the SERS enhancement is dominant. Finally, the resonant TERS spectrum from CdSe QDs was obtained using electrochemically etched gold tips providing an enhancement on the order of 10(4). This is an important step towards the detection of the phonon spectrum from a single QD.
Collapse
Affiliation(s)
- E Sheremet
- Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Kazemi-Zanjani N, Gobbo P, Zhu Z, Workentin MS, Lagugné-Labarthet F. High-resolution Raman imaging of bundles of single-walled carbon nanotubes by tip-enhanced Raman spectroscopy. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0247] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Bundles of single-walled carbon nanotubes (SWCNTs) prepared by plasma torch method and further purified, are deposited over a glass coverslip to estimate the spatial resolution of tip-enhanced Raman spectroscopy measurements. For this purpose, near-field Raman maps and spectra of isolated bundles of carbon nanotubes are collected using optimized experimental conditions such as a tightly focused beam using a 1.4 numerical aperture oil immersion microscope objective and a gold coated atomic force microscope probe illuminated by a radially polarized 632.8 nm wavelength to selectively excite the localized surface plasmon confined at the extremity of the tip. The near-field nature of the collected Raman signals is evaluated through measuring the decay of the Raman signal with respect to the tip-sample separation.
Collapse
Affiliation(s)
- Nastaran Kazemi-Zanjani
- Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151Richmond Street, London, ON N6A 5B7, Canada
| | - Pierangelo Gobbo
- Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151Richmond Street, London, ON N6A 5B7, Canada
| | - Ziyan Zhu
- Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151Richmond Street, London, ON N6A 5B7, Canada
| | - Mark S. Workentin
- Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151Richmond Street, London, ON N6A 5B7, Canada
| | - François Lagugné-Labarthet
- Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151Richmond Street, London, ON N6A 5B7, Canada
| |
Collapse
|