1
|
Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode. Angew Chem Int Ed Engl 2023; 62:e202216604. [PMID: 36592114 DOI: 10.1002/anie.202216604] [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: 11/10/2022] [Revised: 12/21/2022] [Accepted: 01/02/2023] [Indexed: 01/03/2023]
Abstract
Molecular-level insight into interfacial water at a buried electrode interface is essential in electrochemistry, but spectroscopic probing of the interface remains challenging. Here, using surface-specific heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy, we directly access the interfacial water in contact with the graphene electrode supported on calcium fluoride (CaF2 ). We find phase transition-like variations of the HD-SFG spectra vs. applied potentials, which arises not from the charging/discharging of graphene but from the charging/discharging of the CaF2 substrate through the pseudocapacitive process. The potential-dependent spectra are nearly identical to the pH-dependent spectra, evidencing that the pseudocapacitive behavior is associated with a substantial local pH change induced by water dissociation between the CaF2 and graphene. Our work evidences the local molecular-level effects of pseudocapacitive charging at an electrode/aqueous electrolyte interface.
Collapse
|
2
|
Chemistry governs water organization at a graphene electrode. Nature 2023; 615:E1-E2. [PMID: 36859590 DOI: 10.1038/s41586-022-05669-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 12/19/2022] [Indexed: 03/03/2023]
|
3
|
Playing catch and release with single molecules: mechanistic insights into plasmon-controlled nanogaps. NANOSCALE 2023; 15:497-506. [PMID: 36394540 DOI: 10.1039/d2nr05448e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Single-molecule (SM) detection is essential for investigating processes at the molecular level. Nanogap-based detection approaches have proven to be highly accurate SM capture and detection platforms in the last decade. Unfortunately, these approaches face several inherent drawbacks, such as short detection times and the effects of Brownian motion, that can hinder molecular capture. Nanogap-based SM detection approaches have been successfully coupled to optical-based setups to exploit nearfield-assisted trapping to overcome these drawbacks and thus improve SM capture and detection. Here we present the first mechanistic study of nearfield effects on SM capture and release in nanogaps, using unsupervised machine learning methods based on hidden Markov models. We show that the nearfield strength can manipulate the kinetics of the SM capture and release processes. With increasing field strength, the rate constant of the capture kinetics increase while the release kinetics decrease, favouring the former over the latter. As a result, the SM capture state is more likely and more stable than the release state above a specific threshold nearfild strength. We have also estimated the decrease in the capture free-energy profile and the increase in the release profiles to be around 5 kJ mol-1 for the laser powers employed, ranging from laser-OFF conditions to 11 mW μm-2. We envisage that our findings can be combined with the electrocatalytic capabilities of the (nearfield) nanogap to develop next-generation molecular nanoreactors. This approach will open the door to highly efficient SM catalysis with precise extended monitoring timescales facilitated through the longer residence times of the reactant trapped inside the nanogap.
Collapse
|
4
|
Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode. Angew Chem Int Ed Engl 2023. [DOI: 10.1002/ange.202216604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
5
|
Abstract
Ice nucleation‐active bacteria are the most efficient ice nucleators known, enabling the crystallization of water at temperatures close to 0 °C, thereby overcoming the kinetically hindered phase transition process at these conditions. Using highly specialized ice‐nucleating proteins (INPs), they can cause frost damage to plants and influence the formation of clouds and precipitation in the atmosphere. In nature, the bacteria are usually found in aqueous environments containing ions. The impact of ions on bacterial ice nucleation efficiency, however, has remained elusive. Here, we demonstrate that ions can profoundly influence the efficiency of bacterial ice nucleators in a manner that follows the Hofmeister series. Weakly hydrated ions inhibit bacterial ice nucleation whereas strongly hydrated ions apparently facilitate ice nucleation. Surface‐specific sum‐frequency generation spectroscopy and molecular dynamics simulations reveal that the different effects are due to specific interactions of the ions with the INPs on the surface of the bacteria. Our results demonstrate that heterogeneous ice nucleation facilitated by bacteria strongly depends upon the nature of the ions, and specific ion–protein interactions are essential for the complete description of heterogeneous ice nucleation by bacteria.
Collapse
|
6
|
Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory. ACS Catal 2020; 10:12716-12726. [PMID: 33194302 PMCID: PMC7654126 DOI: 10.1021/acscatal.0c02752] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/26/2020] [Indexed: 11/29/2022]
Abstract
![]()
Molecular understanding of the electrochemical
oxidation of metals
and the electro-reduction of metal oxides is of pivotal importance
for the rational design of catalyst-based devices where metal(oxide)
electrodes play a crucial role. Operando monitoring
and reliable identification of reacting species, however, are challenging
tasks because they require surface-molecular sensitive and specific
experiments under reaction conditions and sophisticated theoretical
calculations. The lack of molecular insight under operating conditions
is largely due to the limited availability of operando tools and to date still hinders a quick technological advancement
of electrocatalytic devices. Here, we present a combination of advanced
density functional theory (DFT) calculations considering implicit
solvent contributions and time-resolved electrochemical surface-enhanced
Raman spectroscopy (EC-SERS) to identify short-lived reaction intermediates
during the showcase electro-reduction of Au oxide (AuOx) in sulfuric
acid over several tens of seconds. The EC-SER spectra provide evidence
for temporary Au-OH formation and for the asynchronous adsorption
of (bi)sulfate ions at the surface during the reduction process. Spectral
intensity fluctuations indicate an OH/(bi)sulfate turnover period
of 4 s. As such, the presented EC-SERS potential jump approach combined
with implicit solvent DFT simulations allows us to propose a reaction
mechanism and prove that short-lived Au-OH intermediates also play
an active role during the AuOx electro-reduction in acidic media,
implying their potential relevance also for other electrocatalytic
systems operating at low pH, like metal corrosion, the oxidation of
CO, HCOOH, and other small organic molecules, and the oxygen evolution
reaction.
Collapse
|
7
|
Beam Modulation for Aberration Control and Signal Enhancement in Tip-Enhanced Raman Spectroscopy. APPLIED SPECTROSCOPY 2020; 74:1407-1413. [PMID: 32820942 DOI: 10.1177/0003702820938065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Tip-enhanced Raman spectroscopy (TERS) provides the sensitivity required to obtain the vibrational fingerprint of few molecules. While single molecule detection has been demonstrated in UHV experiments, the sensitivity of the technique in ambient, liquid and electrochemical conditions is still limited. In this work, we present a new strategy to increase the signal-to-noise in TERS by spatial light modulation. We iteratively optimize the phase of the excitation beam employing two different feedback mechanisms. In one optimization protocol, we monitor the spectral changes upon aberration correction and tight far-field focusing. In a second protocol, we use a phase-optimization strategy where TER spectra are directly used for feedback. Far-field tight focusing results in average signal enhancements of a factor of 3.5 in air and has no impact on TER signals obtained from solid/liquid interfaces. Using the TER spectrum as direct feedback, we obtain average signal enhancements between a factor of 2.6 in liquid and 4.3 in air. In individual cases, some bands increase by more than one order of magnitude in intensity upon spatial light modulation. Importantly, phase modulation in addition allowed the retrieval of bands that were initially not discernible from the noise. The proposed beam-modulation strategy can be easily implemented in existing TERS instruments and can help to push the detection limit of the technique in applications where the signal-to-noise level is low.
Collapse
|
8
|
Correlated interfacial water transport and proton conductivity in perfluorosulfonic acid membranes. Proc Natl Acad Sci U S A 2019; 116:8715-8720. [PMID: 30988207 PMCID: PMC6500179 DOI: 10.1073/pnas.1817470116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Water must be effectively transported and is also essential for maximizing proton conductivity within fuel-cell proton-exchange membranes (PEMs). Therefore, identifying relationships between PEM properties, water transport, and proton conductivity is essential for designing optimal PEMs. Here, we use coherent Raman spectroscopy to quantify real-time, in situ diffusivities of water subspecies, bulk-like and nonbulk-like (interfacial) water, in five different perfluorosulfonic acid (PFSA) PEMs. Although the PEMs were chemically diverse, water transport within them followed the same rule: Total water diffusivity could be represented by a linear combination of the bulk-like and interfacial water diffusivities. Moreover, the diffusivity of interfacial water was consistently larger than that of bulk-like water. These measurements of microscopic transport were combined with through-plane proton conductivity measurements to reveal the correlation between interfacial water transport and proton conductivity. Our results demonstrate the importance of maximizing the diffusivity and fractional contribution of interfacial water to maximize the proton conductivity in PFSA PEMs.
Collapse
|
9
|
Stark effect or coverage dependence? Disentangling the EC-SEIRAS vibrational shift of sulfate on Au(111). J Chem Phys 2019; 150:041709. [DOI: 10.1063/1.5047941] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
|
10
|
Characterizing the hydrophobic-to-hydrophilic transition of electrolyte structuring in proton exchange membrane mimicking surfaces. Phys Chem Chem Phys 2018; 20:11722-11729. [DOI: 10.1039/c8cp01625a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The surface density of charged sulfonic acid head groups in a perfluorosulfonic acid (PFSA) proton exchange membrane determines the hydrophilicity of the ionic channels and is thus critical for the structuring and transport of water and protons.
Collapse
|
11
|
Electrochemical TERS Elucidates Potential‐Induced Molecular Reorientation of Adenine/Au(111). Angew Chem Int Ed Engl 2017. [DOI: 10.1002/anie.201704460] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
12
|
Cover Picture: Raman Under Water - Nonlinear and Nearfield Approaches for Electrochemical Surface Science (ChemElectroChem 8/2017). ChemElectroChem 2017. [DOI: 10.1002/celc.201700613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
13
|
Raman Under Water - Nonlinear and Nearfield Approaches for Electrochemical Surface Science. ChemElectroChem 2017; 4:1814-1823. [PMID: 28920009 PMCID: PMC5575488 DOI: 10.1002/celc.201700293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Indexed: 11/06/2022]
Abstract
Electrochemistry is re-gaining attention among scientists because the complex interplay between electronic and chemical interfacial processes lies at the bottom of a broad range of important research disciplines like alternative energy conversion or green catalysis and synthesis. While rapid progress has been made in recent years regarding novel technological applications, the community increasingly recognizes that the understanding of the molecular processes that govern macroscopic device properties is still rather limited - which hinders a systematic and more complete exploration of novel material and functionality space. Here, we discuss advanced Raman spectroscopies as valuable analysis tools for electrochemists. The chemical nature of a material and its interaction with the environment is contained in the label-free vibrational fingerprint over a broad energy range so that organic species, solid-state materials, and hybrids thereof can be investigated alike. For surface studies, the inherently small Raman scattering cross sections can be overcome with advanced nonlinear or nearfield-based approaches that provide signal enhancements between three and seven orders of magnitude, sufficient to detect few scatterers in nano-confined spaces or adsorbate (sub)monolayers. Our article highlights how advanced Raman techniques with extreme chemical, spatial and temporal resolution constitute valuable alternative surface analysis tools and provide otherwise inaccessible information about complex interfacial (electro)chemical processes.
Collapse
|
14
|
Electrochemical TERS Elucidates Potential‐Induced Molecular Reorientation of Adenine/Au(111). Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704460] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
15
|
Raman under Water: Nonlinear and Nearfield Approaches for Electrochemical Surface Science. ChemElectroChem 2017. [DOI: 10.1002/celc.201700612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
16
|
Advanced SERS Sensor Based on Capillarity-Assisted Preconcentration through Gold Nanoparticle-Decorated Porous Nanorods. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1603947. [PMID: 28440003 DOI: 10.1002/smll.201603947] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 02/26/2017] [Indexed: 06/07/2023]
Abstract
A preconcentrating surface-enhanced Raman scattering (SERS) sensor for the analysis of liquid-soaked tissue, tiny liquid droplets and thin liquid films without the necessity to collect the analyte is reported. The SERS sensor is based on a block-copolymer membrane containing a spongy-continuous pore system. The sensor's upper side is an array of porous nanorods having tips functionalized with Au nanoparticles. Capillarity in combination with directional evaporation drives the analyte solution in contact with the flat yet nanoporous underside of the SERS sensor through the continuous nanopore system toward the nanorod tips where non-volatile components of the analyte solution precipitate at the Au nanoparticles. The nanorod architecture increases the sensor surface in the detection volume and facilitates analyte preconcentration driven by directional solvent evaporation. The model analyte 5,5'-dithiobis(2-nitrobenzoic acid) can be detected in a 1 × 10-3 m solution ≈300 ms after the sensor is brought into contact with the solution. Moreover, a sensitivity of 0.1 ppm for the detection of the dissolved model analyte is achieved.
Collapse
|
17
|
Trimesic acid on Cu in ethanol: Potential-dependent transition from 2-D adsorbate to 3-D metal-organic framework. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2017.01.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
18
|
Abstract
In this work, we evaluate the dependence of tip-enhanced Raman (TER) spectra of a monolayer of thiophenol at a Au(111) electrode on the scanning tunneling microscope’s tunneling current set-point and bias voltage parameters. We find an increase of the TER intensity upon set-point increase or bias decrease as expected from a gap-distance reduction. The relations obtained follow a theoretical model considering a simple gap-distance change when tuning the mentioned parameters. We find that the value of the bias voltage affects the TER intensity to a larger extent than the current set-point. Therefore it is advisable to work in a low-bias regime when aiming for ultrasensitive TER measurements.
Collapse
|
19
|
Versatile Side-Illumination Geometry for Tip-Enhanced Raman Spectroscopy at Solid/Liquid Interfaces. Anal Chem 2016; 88:7108-14. [DOI: 10.1021/acs.analchem.6b01080] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
20
|
Nanoscale Distribution of Sulfonic Acid Groups Determines Structure and Binding of Water in Nafion Membranes. Angew Chem Int Ed Engl 2016; 55:4011-5. [PMID: 26895211 PMCID: PMC5021165 DOI: 10.1002/anie.201600219] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/02/2016] [Indexed: 11/13/2022]
Abstract
The connection between the nanoscale structure of two chemically equivalent, yet morphologically distinct Nafion fuel-cell membranes and their macroscopic chemical properties is demonstrated. Quantification of the chemical interactions between water and Nafion reveals that extruded membranes have smaller water channels with a reduced sulfonic acid head group density compared to dispersion-cast membranes. As a result, a disproportionally large amount of non-bulk water molecules exists in extruded membranes, which also exhibit larger proton conductivity and larger water mobility compared to cast membranes. The differences in the physicochemical properties of the membranes, that is, the chemical constitution of the water channels and the local water structure, and the accompanying differences in macroscopic water and proton transport suggest that the chemistry of nanoscale channels is an important, yet largely overlooked parameter that influences the functionality of fuel-cell membranes.
Collapse
|
21
|
Nanoscale Distribution of Sulfonic Acid Groups Determines Structure and Binding of Water in Nafion Membranes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600219] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
22
|
Unraveling a two-step oxidation mechanism in electrochemical Cu-MOF synthesis. Chem Commun (Camb) 2016; 52:4722-5. [DOI: 10.1039/c6cc00534a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
To employ the full potential of electrochemical (ec) synthesis to grow metal–organic frameworks (MOFs) in more complex organizations at the mesoscale, it is vital to understand the underlying crystallization reaction pathway.
Collapse
|
23
|
Polymer brush functionalized SiO2 nanoparticle based Nafion nanocomposites: a novel avenue to low-humidity proton conducting membranes. Polym Chem 2015. [DOI: 10.1039/c5py00514k] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Polymer brush grafted SiO2 NPs provide Nafion nanocomposite membranes with superior proton conductivities at ambient and moderately high temperatures over the entire range of relative humidity.
Collapse
|
24
|
Understanding Physical Chemistry. By Dor Ben-Amotz. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/anie.201405473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
25
|
Understanding Physical Chemistry. Von Dor Ben-Amotz. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201405473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
26
|
Watching Orientational Ordering at the Nanoscale with Coherent Anti-Stokes Raman Microscopy. Chemistry 2013; 19:11822-30. [DOI: 10.1002/chem.201301394] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
27
|
Inside Cover: Host-Guest Geometry in Pores of Zeolite ZSM-5 Spatially Resolved with Multiplex CARS Spectromicroscopy (Angew. Chem. Int. Ed. 6/2012). Angew Chem Int Ed Engl 2012. [DOI: 10.1002/anie.201108164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
28
|
Innentitelbild: Wirt-Gast-Geometrie in Zeolithporen von ZSM-5: räumlich aufgelöst durch CARS-Spektromikroskopie (Angew. Chem. 6/2012). Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
29
|
Tracing catalytic conversion on single zeolite crystals in 3D with nonlinear spectromicroscopy. J Am Chem Soc 2011; 134:1124-9. [PMID: 22118571 DOI: 10.1021/ja2088025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cost- and material-efficient development of next-generation catalysts would benefit greatly from a molecular-level understanding of the interaction between reagents and catalysts in chemical conversion processes. Here, we trace the conversion of alkene and glycol in single zeolite catalyst particles with unprecedented chemical and spatial resolution. Combined nonlinear Raman and two-photon fluorescence spectromicroscopies reveal that alkene activation constitutes the first reaction step toward glycol etherification and allow us to determine the activation enthalpy of the resulting carbocation formation. Considerable inhomogeneities in local reactivity are observed for micrometer-sized catalyst particles. Product ether yields observed on the catalyst are ca. 5 times higher than those determined off-line. Our findings are relevant for other heterogeneous catalytic processes and demonstrate the immense potential of novel nonlinear spectromicroscopies for catalysis research.
Collapse
|
30
|
Host-Guest Geometry in Pores of Zeolite ZSM-5 Spatially Resolved with Multiplex CARS Spectromicroscopy. Angew Chem Int Ed Engl 2011; 51:1343-7. [DOI: 10.1002/anie.201106447] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Indexed: 11/06/2022]
|
31
|
Wirt-Gast-Geometrie in Zeolithporen von ZSM-5: räumlich aufgelöst durch CARS-Spektromikroskopie. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201106447] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
32
|
CARS microscopy for the visualization of micrometer-sized iron oxide MRI contrast agents in living cells. BIOMEDICAL OPTICS EXPRESS 2011; 2:2470-2483. [PMID: 21991541 PMCID: PMC3184857 DOI: 10.1364/boe.2.002470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 05/31/2023]
Abstract
Micrometer-sized iron oxide particles (MPIOs) attract increasing interest as contrast agents for cellular tracking by clinical Magnetic Resonance Imaging (MRI). Despite the great potential of MPIOs for in vivo imaging of labeled cells, little is known on the intracellular localization of these particles following uptake due to the lack of techniques with the ability to monitor the particle uptake in vivo at single-cell level. Here, we show that coherent anti-Stokes Raman scattering (CARS) microscopy enables non-invasive, label-free imaging of MPIOs in living cells with sub-micron resolution in three dimensions. CARS allows simultaneous visualization of the cell framework and the MPIOs, where the particles can be readily distinguished from other cellular components of comparable dimensions, and localized inside the cell.
Collapse
|
33
|
Surface Enhanced Raman Spectroscopy. Analytical, Biophysical and Life Science Applications. Herausgegeben von Sebastian Schlücker. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201103289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
34
|
Surface Enhanced Raman Spectroscopy. Analytical, Biophysical and Life Science Applications. Edited by Sebastian Schlücker. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/anie.201103289] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
35
|
|
36
|
Abstract
The use of an illuminated scanning probe tip to greatly enhance Raman scattering from the sample underneath the tip is one of the most intriguing developments in optical spectroscopy, and the steeply increasing number of publications per year shows that chemists, physicists and biologists alike recognize the importance and great potential of this technique. With tip-enhanced Raman spectroscopy (TERS), one of the main goals in surface science has been achieved, namely the combination of scanning probe microscopy and optical spectroscopy such as Raman spectroscopy. Important here is the use of the tip as an optical antenna to substantially increase the emitted radiation and to simultaneously improve the optical resolution much beyond the Abbe diffraction limit. This permits the correlation of topographic and chemical information of the same surface region. The synergy of detailed insight in morphology and the chemical nature of the target species facilitates data interpretation significantly and enables characterization of interfaces at the nanometer scale. A wide variety of substrates and sample molecules have been studied with TERS since the first publication of tip-enhanced Raman spectra, and the technique has reached a first level of maturity on its 10th birthday, with TERS applications extending into various research fields from surface chemistry over biology to nanoscale physics.
Collapse
|
37
|
Label-Free Imaging of Lipophilic Bioactive Molecules during Lipid Digestion by Multiplex Coherent Anti-Stokes Raman Scattering Microspectroscopy. J Am Chem Soc 2010; 132:8433-9. [DOI: 10.1021/ja102069d] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
38
|
Tip-Enhanced Raman Spectroscopic Studies of the Hydrogen Bonding between Adenine and Thymine Adsorbed on Au (111). Chemphyschem 2010; 11:1662-5. [DOI: 10.1002/cphc.200900883] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
39
|
In Situ Discrimination between Axially Complexed and Ligand-Free Co Porphyrin on Au(111) with Tip-Enhanced Raman Spectroscopy. Chemphyschem 2009; 10:1794-8. [DOI: 10.1002/cphc.200900182] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
40
|
The formation of two Ag UPD layers on stepped Pt single crystal electrodes and their restructuring by co-adsorption of CO. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2009.03.088] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
41
|
Co-adsorption of CO onto a Ag-modified Pt(111) — Restructuring of a Ag UPD layer monitored by EC-STM. Phys Chem Chem Phys 2008; 10:1555-61. [DOI: 10.1039/b714816j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
42
|
Toward Raman fingerprints of single dye molecules at atomically smooth Au(111). J Am Chem Soc 2007; 128:14721-7. [PMID: 17090060 DOI: 10.1021/ja065820b] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The creation of a highly enhanced electromagnetic (EM) field underneath a scanning tunneling microscope (STM) tip enables Raman spectroscopic studies of organic submonolayer adsorbates at atomically smooth single crystalline surfaces. To study the sensitivity of this technique, tip-enhanced resonance Raman (TERR) spectra of the dye malachite green isothiocyanate on Au(111) in combination with the corresponding STM images of the probed surface region were analyzed. The detection limit for unambiguous identification of the dye and semiquantitative determination of the surface coverage reaches < or =0.7 pmol/cm(2), or approximately five molecules present in the enhanced-field region, which is confirmed by STM images. Because of well-defined adsorption sites at atomically smooth Au(111) surfaces, no variation in band positions or relative band intensities was observed at the single- or few-molecule detection level when employing TERR spectroscopy.
Collapse
|
43
|
|