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Liu D, Li L, Jiang N. Nanoscale Chemical Probing of Metal-Supported Ultrathin Ferrous Oxide via Tip-Enhanced Raman Spectroscopy and Scanning Tunneling Microscopy. CHEMICAL & BIOMEDICAL IMAGING 2024; 2:345-351. [PMID: 38817320 PMCID: PMC11134605 DOI: 10.1021/cbmi.4c00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/04/2024] [Accepted: 03/11/2024] [Indexed: 06/01/2024]
Abstract
Metal-supported ultrathin ferrous oxide (FeO) has attracted immense interest in academia and industry due to its widespread applications in heterogeneous catalysis. However, chemical insight into the local structural characteristics of FeO, despite its critical importance in elucidating structure-property relationships, remains elusive. In this work, we report the nanoscale chemical probing of gold (Au)-supported ultrathin FeO via ultrahigh-vacuum tip-enhanced Raman spectroscopy (UHV-TERS) and scanning tunneling microscopy (STM). For comparative analysis, single-crystal Au(111) and Au(100) substrates are used to tune the interfacial properties of FeO. Although STM images show distinctly different moiré superstructures on FeO nanoislands on Au(111) and Au(100), TERS demonstrates the same chemical nature of FeO by comparable vibrational features. In addition, combined TERS and STM measurements identify a unique wrinkled FeO structure on Au(100), which is correlated to the reassembly of the intrinsic Au(100) surface reconstruction due to FeO deposition. Beyond revealing the morphologies of ultrathin FeO on Au substrates, our study provides a thorough understanding of the local interfacial properties and interactions of FeO on Au, which could shed light on the rational design of metal-supported FeO catalysts. Furthermore, this work demonstrates the promising utility of combined TERS and STM in chemically probing the structural properties of metal-supported ultrathin oxides on the nanoscale.
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Affiliation(s)
- Dairong Liu
- Department
of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
| | - Linfei Li
- Department
of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
| | - Nan Jiang
- Department
of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
- Department
of Physics, University of Illinois Chicago, Chicago, Illinois 60607, United States
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Wu H, Li G, Hou J, Sotthewes K. Probing surface properties of organic molecular layers by scanning tunneling microscopy. Adv Colloid Interface Sci 2023; 318:102956. [PMID: 37393823 DOI: 10.1016/j.cis.2023.102956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 07/04/2023]
Abstract
In view of the relevance of organic thin layers in many fields, the fundamentals, growth mechanisms, and dynamics of thin organic layers, in particular thiol-based self-assembled monolayers (SAMs) on Au(111) are systematically elaborated. From both theoretical and practical perspectives, dynamical and structural features of the SAMs are of great intrigue. Scanning tunneling microscopy (STM) is a remarkably powerful technique employed in the characterization of SAMs. Numerous research examples of investigation about the structural and dynamical properties of SAMs using STM, sometimes combined with other techniques, are listed in the review. Advanced options to enhance the time resolution of STM are discussed. Additionally, we elaborate on the extremely diverse dynamics of various SAMs, such as phase transitions and structural changes at the molecular level. In brief, the current review is expected to supply a better understanding and novel insights regarding the dynamical events happening in organic SAMs and how to characterize these processes.
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Affiliation(s)
- Hairong Wu
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China.
| | - Genglin Li
- College of Science, China University of Petroleum-Beijing, Beijing 102249, China
| | - Jirui Hou
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, the Netherlands.
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Willeford K. The Luminescence Hypothesis of Olfaction. SENSORS (BASEL, SWITZERLAND) 2023; 23:1333. [PMID: 36772376 PMCID: PMC9919928 DOI: 10.3390/s23031333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/12/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
A new hypothesis for the mechanism of olfaction is presented. It begins with an odorant molecule binding to an olfactory receptor. This is followed by the quantum biology event of inelastic electron tunneling as has been suggested with both the vibration and swipe card theories. It is novel in that it is not concerned with the possible effects of the tunneled electrons as has been discussed with the previous theories. Instead, the high energy state of the odorant molecule in the receptor following inelastic electron tunneling is considered. The hypothesis is that, as the high energy state decays, there is fluorescence luminescence with radiative emission of multiple photons. These photons pass through the supporting sustentacular cells and activate a set of olfactory neurons in near-simultaneous timing, which provides the temporal basis for the brain to interpret the required complex combinatorial coding as an odor. The Luminescence Hypothesis of Olfaction is the first to present the necessity of or mechanism for a 1:3 correspondence of odorant molecule to olfactory nerve activations. The mechanism provides for a consistent and reproducible time-based activation of sets of olfactory nerves correlated to an odor. The hypothesis has a biological precedent: an energy feasibility assessment is included, explaining the anosmia seen with COVID-19, and can be confirmed with existing laboratory techniques.
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Affiliation(s)
- Kenneth Willeford
- Coastal Carolinas Integrated Medicine, 10 Doctors Circle, STE 2, Supply, NC 28462, USA
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Schultz JF, Li L, Mahapatra S, Jiang N. Chemically imaging nanostructures formed by the covalent assembly of molecular building blocks on a surface with ultrahigh vacuum tip-enhanced Raman spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:204008. [PMID: 35196263 DOI: 10.1088/1361-648x/ac57d8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Surface-bound reactions have become a viable method to develop nanoarchitectures through bottom-up assembly with near atomic precision. However, the bottom-up fabrication of nanostructures on surfaces requires careful consideration of the intrinsic properties of the precursors and substrate as well as the complex interplay of any interactions that arise in the heterogeneous two-dimensional (2D) system. Therefore, it becomes necessary to consider these systems with characterization methods sensitive to such properties with suitable spatial resolution. Here, low temperature ultrahigh vacuum scanning tunneling microscopy (STM) and tip-enhanced Raman spectroscopy (TERS) were used to investigate the formation of 2D covalent networks via coupling reactions of tetra(4-bromophenyl)porphyrin (Br4TPP) molecules on a Ag(100) substrate. Through the combination of STM topographic imaging and TERS vibrational fingerprints, the conformation of molecular precursors on the substrate was understood. Following the thermally activated coupling reaction, STM and TERS imaging confirm the covalent nature of the 2D networks and suggest that the apparent disorder arises from molecular flexibility.
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Affiliation(s)
- Jeremy F Schultz
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States of America
| | - Linfei Li
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States of America
| | - Sayantan Mahapatra
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States of America
| | - Nan Jiang
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States of America
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Mahapatra S, Schultz JF, Li L, Zhang X, Jiang N. Controlling Localized Plasmons via an Atomistic Approach: Attainment of Site-Selective Activation inside a Single Molecule. J Am Chem Soc 2022; 144:2051-2055. [PMID: 34978804 DOI: 10.1021/jacs.1c11547] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chemical reactions such as bond dissociation and formation assisted by localized surface plasmons (LSPs) of noble metal nanostructures hold promise in solar-to-chemical energy conversion. However, the precise control of localized plasmons to activate a specific moiety of a molecule, in the presence of multiple chemically equivalent parts within a single molecule, is scarce due to the relatively large lateral distribution of the plasmonic field. Herein, we report the plasmon-assisted dissociation of a specific molecular site (C-Si bond) within a polyfunctional molecule adsorbed on a Cu(100) surface in the scanning tunneling microscope (STM) junction. The molecular site to be activated can be selected by carefully positioning the tip and bringing the tip extremely close to the molecule (atomistic approach), thereby achieving plasmonic nanoconfinement at the tip apex. Furthermore, multiple reactive sites are activated in a sequential manner at the sub-molecular scale, and different sets of products are created and visualized by STM topography and density functional theory (DFT) modeling. The illustration of site-selective activation achieved by localized surface plasmons implies the realization of molecular-scale resolution for bond-selected plasmon-induced chemistry.
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Affiliation(s)
- Sayantan Mahapatra
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
| | - Jeremy F Schultz
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
| | - Linfei Li
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
| | - Xu Zhang
- Department of Physics and Astronomy, California State University, Northridge, California 91330, United States
| | - Nan Jiang
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, United States
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Li L, Schultz JF, Mahapatra S, Liu X, Shaw C, Zhang X, Hersam MC, Jiang N. Angstrom-Scale Spectroscopic Visualization of Interfacial Interactions in an Organic/Borophene Vertical Heterostructure. J Am Chem Soc 2021; 143:15624-15634. [PMID: 34369773 DOI: 10.1021/jacs.1c04380] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Two-dimensional boron monolayers (i.e., borophene) hold promise for a variety of energy, catalytic, and nanoelectronic device technologies due to the unique nature of boron-boron bonds. To realize its full potential, borophene needs to be seamlessly interfaced with other materials, thus motivating the atomic-scale characterization of borophene-based heterostructures. Here, we report the vertical integration of borophene with tetraphenyldibenzoperiflanthene (DBP) and measure the angstrom-scale interfacial interactions with ultrahigh-vacuum tip-enhanced Raman spectroscopy (UHV-TERS). In addition to identifying the vibrational signatures of adsorbed DBP, TERS reveals subtle ripples and compressive strains of the borophene lattice underneath the molecular layer. The induced interfacial strain is demonstrated to extend in borophene by ∼1 nm beyond the molecular region by virtue of 5 Å chemical spatial resolution. Molecular manipulation experiments prove the molecular origins of interfacial strain in addition to allowing atomic control of local strain with magnitudes as small as ∼0.6%. In addition to being the first realization of an organic/borophene vertical heterostructure, this study demonstrates that UHV-TERS is a powerful analytical tool to spectroscopically investigate buried and highly localized interfacial characteristics at the atomic scale, which can be applied to additional classes of heterostructured materials.
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Affiliation(s)
- Linfei Li
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Jeremy F Schultz
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Sayantan Mahapatra
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Xiaolong Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Chasen Shaw
- Department of Physics and Astronomy, California State University, Northridge, Northridge, California 91330, United States
| | - Xu Zhang
- Department of Physics and Astronomy, California State University, Northridge, Northridge, California 91330, United States
| | - Mark C Hersam
- Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.,Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Nan Jiang
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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Yokota Y, Kim Y. Molecular Scale Assessments of Electrochemical Interfaces: In Situ and Ex Situ Approaches. CHEM LETT 2021. [DOI: 10.1246/cl.200735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yasuyuki Yokota
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- JST PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Yousoo Kim
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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