scholarly journals Conformational heterogeneity of molecules physisorbed on a gold surface at room temperature

2021 ◽  
Author(s):  
Mingu Kang ◽  
Hyun Woo Kim ◽  
Elham Oleiki ◽  
Yeonjeong Koo ◽  
Hyeongwoo Lee ◽  
...  
Keyword(s):  
Single Molecule ◽  
Density Functional ◽  
Room Temperature ◽  
Gold Surface ◽  
Chemical Imaging ◽  
Conformational Heterogeneity ◽  
Single Molecule Level ◽  
Cresyl Blue ◽  
Tip Enhanced Raman Spectroscopy ◽  
Spectroscopy Studies

Abstract A quantitative single-molecule tip-enhanced Raman spectroscopy (TERS) study at room temperature remained a challenge due to the rapid structural dynamics of molecules exposed to air. Here, we demonstrate the hyperspectral TERS imaging of single or a few brilliant cresyl blue (BCB) molecules at room temperature, along with quantitative spectral analyses. Robust chemical imaging is enabled by the freeze-frame approach using a thin Al2O3 capping layer, which suppresses spectral diffusions and inhibits chemical reactions and contaminations in air. For the molecules resolved spatially in the TERS image, a clear Raman peak variation up to 7.5 cm-1 is observed, which cannot be found in molecular ensembles. From density functional theory-based quantitative analyses of the varied TERS peaks, we reveal the conformational heterogeneity at the single-molecule level. This work provides a facile way to investigate the single-molecule properties in interacting media, expanding the scope of single-molecule vibrational spectroscopy studies.

scholarly journals Optical probes of molecules as nano-mechanical switches

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dean Kos ◽  
Giuliana Di Martino ◽  
Alexandra Boehmke ◽  
Bart de Nijs ◽  
Dénes Berta ◽  
...  
Keyword(s):  
Molecular Electronics ◽  
Single Molecule ◽  
Electrical Transport ◽  
Density Functional ◽  
Information Technologies ◽  
Electronic Device ◽  
Density Functional Theory Calculations ◽  
Molecular Junction ◽  
Single Molecule Level ◽  
Ultralow Energy

AbstractMolecular electronics promises a new generation of ultralow-energy information technologies, based around functional molecular junctions. Here, we report optical probing that exploits a gold nanoparticle in a plasmonic nanocavity geometry used as one terminal of a well-defined molecular junction, deposited as a self-assembled molecular monolayer on flat gold. A conductive transparent cantilever electrically contacts individual nanoparticles while maintaining optical access to the molecular junction. Optical readout of molecular structure in the junction reveals ultralow-energy switching of ∼50 zJ, from a nano-electromechanical torsion spring at the single molecule level. Real-time Raman measurements show these electronic device characteristics are directly affected by this molecular torsion, which can be explained using a simple circuit model based on junction capacitances, confirmed by density functional theory calculations. This nanomechanical degree of freedom is normally invisible and ignored in electrical transport measurements but is vital to the design and exploitation of molecules as quantum-coherent electronic nanodevices.

Room-temperature tracking of chiral recognition process at the single-molecule level

Nano Research ◽  
2015 ◽  
Vol 8 (11) ◽  
pp. 3505-3511 ◽  
Author(s):  
Ruilin Xu ◽  
Juan Liu ◽  
Feng Chen ◽  
Nianhua Liu ◽  
Yingxiang Cai ◽  
...  
Keyword(s):  
Single Molecule ◽  
Chiral Recognition ◽  
Room Temperature ◽  
Single Molecule Level ◽  
Recognition Process ◽  
Temperature Tracking

scholarly journals Spin-Transport Tuning of Individual Magnetic Mn-Salophen Molecule via Chemical Adsorption

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1747 ◽  
Author(s):  
Feifei Li ◽  
Jing Huang ◽  
Jianing Wang ◽  
Qunxiang Li
Keyword(s):  
Single Molecule ◽  
Magnetic Moment ◽  
Density Functional ◽  
Spin Transport ◽  
Density Functional Theory Calculations ◽  
Chemical Adsorption ◽  
Adsorption Effect ◽  
Single Molecule Level ◽  
Filtering Effect ◽  
Spin Filtering

Control over spin states at the single molecule level is a key issue in the emerging field of molecular spintronics. Here, we explore the chemical adsorption effect on the magnetic and spin-transport properties of individual magnetic molecule by performing extensive density functional theory calculations in combining with non-equilibrium Green’s function method. Theoretical results clearly reveal that the molecular magnetic moment of Mn-salophen can be effectively tuned by adsorbing F and CO on the central Mn cation, while the adsorbed NO molecule quenches the molecular magnetic moment. Without chemical adsorption, the currents through Mn-salophen molecular junction just show a little distinction for two spin channels, which agrees well with previous investigation. Remarkably, the conductive channel can be switched from the spin-up electrons to the spin-down electrons via adsorbing F and CO, respectively, and the corresponding two Mn-salophen molecular junctions with chemical modifications display nearly perfect spin-filtering effect. The observed spin switch and the predicted spin-filtering effect via chemical adsorption indicates that Mn-salophen holds potential applications in molecular spintronic devices.

scholarly journals Detecting Air Pollutant Molecules Using Tube-Shaped Single Electron Transistor

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7098
Author(s):  
Zhongkai Huang ◽  
Xiangyang Peng ◽  
Cheng Peng ◽  
Jin Huang ◽  
Maolin Bo ◽  
...  
Keyword(s):  
Single Molecule ◽  
Room Temperature ◽  
Air Pollutant ◽  
Single Electron ◽  
Single Electron Transistor ◽  
First Principles Calculations ◽  
Single Molecule Level ◽  
Stability Diagrams ◽  
Charge Stability ◽  
Axis Of Symmetry

An air pollution detector is proposed based on a tube-shaped single-electron transistor (SET) sensor. By monitoring the flow control component of the detector, each air pollutant molecule can be placed at the center of a SET nanopore and is treated as an island of the SET device in the same framework. Electron transport in the SET was incoherent, and the performances of the SET were sensitive at the single molecule level. Employing first-principles calculations, electronic features of an air pollutant molecule within a tube-shaped SET environment were found to be independent of the molecule rotational orientations with respect to axis of symmetry, unlike the electronic features in a conventional SET environment. Charge stability diagrams of the island molecules were demonstrated to be distinct for each molecule, and thus they can serve as electronic fingerprints for detection. Using the same setup, quantification of the air pollutant can be realized at room temperature as well. The results presented herein may help provide guidance for the identification and quantification of various types of air pollutants at the molecular level by treating the molecule as the island of the SET component in the proposed detector.

scholarly journals Vibrational modes of aminothiophenol: a TERS and DFT study

2015 ◽  
Vol 17 (29) ◽  
pp. 19134-19138 ◽  
Author(s):  
A. Merlen ◽  
M. Chaigneau ◽  
S. Coussan
Keyword(s):  
Raman Spectroscopy ◽  
Dft Calculations ◽  
Density Functional ◽  
Gold Surface ◽  
Dft Study ◽  
Vibrational Modes ◽  
Tip Enhanced Raman Spectroscopy

We report Tip Enhanced Raman Spectroscopy (TERS) mapping and Density Functional (DFT) calculations of aminothiophenol (ATP) grafted on a gold surface.

Vibrational spectra and chemical imaging of cyclo[18]carbon by tip enhanced Raman spectroscopy

2020 ◽  
Vol 56 (15) ◽  
pp. 2336-2339 ◽  
Author(s):  
Shafqat Hussain ◽  
Huan Chen ◽  
Zhenglong Zhang ◽  
Hairong Zheng
Keyword(s):  
Density Functional Theory ◽  
Raman Spectroscopy ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Chemical Imaging ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Tip Enhanced Raman Spectroscopy

Vibrational modes and tip enhanced Raman spectroscopy (TERS) of cyclo[18]carbon were studied by density functional theory. The TERS images demonstrate the position of the CC bonds.

Coral-like plasmonic probes for tip-enhanced Raman spectroscopy

Nanoscale ◽  
2020 ◽  
Vol 12 (48) ◽  
pp. 24376-24384
Author(s):  
Angela Capaccio ◽  
Antonio Sasso ◽  
Oreste Tarallo ◽  
Giulia Rusciano
Keyword(s):  
Raman Spectroscopy ◽  
Spatial Resolution ◽  
Single Molecule ◽  
Chemical Information ◽  
Single Molecule Level ◽  
Tip Enhanced Raman Spectroscopy ◽  
System Interfaces

Tip-enhanced Raman spectroscopy is a powerful tool for the analysis of system interfaces, enabling access to chemical information with nanometric spatial resolution and sensitivity up to the single molecule level.

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