scholarly journals Room-temperature quantum interference in single perovskite quantum dot junctions

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Haining Zheng ◽  
Songjun Hou ◽  
Chenguang Xin ◽  
Qingqing Wu ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Density Functional ◽  
Room Temperature ◽  
Transport Theory ◽  
Theoretical Calculations ◽  
Interference Effects ◽  
Perovskite Materials ◽  
Metal Halide Perovskite ◽  
Perovskite Quantum Dots ◽  
Quantum Transport Theory

AbstractThe studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge. Herein, we provide the observation of room-temperature quantum interference effects in metal halide perovskite quantum dots (QDs) using the mechanically controllable break junction technique. Single-QD conductance measurements reveal that there are multiple conductance peaks for the CH3NH3PbBr3 and CH3NH3PbBr2.15Cl0.85 QDs, whose displacement distributions match the lattice constant of QDs, suggesting that the gold electrodes slide through different lattice sites of the QD via Au-halogen coupling. We also observe a distinct conductance ‘jump’ at the end of the sliding process, which is further evidence that quantum interference effects dominate charge transport in these single-QD junctions. This conductance ‘jump’ is also confirmed by our theoretical calculations utilizing density functional theory combined with quantum transport theory. Our measurements and theory create a pathway to exploit quantum interference effects in quantum-controlled perovskite materials.

scholarly journals Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1044
Author(s):  
Ayman A. Zaki ◽  
Mohamed Hagar ◽  
Rua B. Alnoman ◽  
Mariusz Jaremko ◽  
Abdul-Hamid Emwas ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Fatty Acid Derivative ◽  
Molecular Structures ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Stable Conformer ◽  
Geometrical Isomers ◽  
Theoretical Approaches

A new liquid crystalline, optical material-based Schiff base core with a near to room-temperature mesophase, (4-methoxybenzylideneamino)phenyl oleate (I), was prepared from a natural fatty acid derivative, and its physical and chemical properties investigated by experimental and theoretical approaches. The molecular structure was confirmed by elemental analysis, FT-IR (Fourier-Transform-Infrared Spectroscopy) and NMR (nuclear magnetic resonance) spectroscopy. Optical and mesomorphic activities were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results show that compound (I) exhibits an enantiotropic monomorphic phase comprising a smectic A phase within the near to room-temperature range. Ordinary and extraordinary refractive indices as well as birefringence with changeable temperatures were analyzed. Microscopic and macroscopic order parameters were also calculated. Theoretical density functional theory (DFT) calculations were carried out to estimate the geometrical molecular structures of the prepared compounds, and the DFT results were used to illustrate the mesomorphic results and optical characteristics in terms of their predicted data. Three geometrical isomers of the prepared compound were investigated to predict the most stable isomer. Many parameters were affected by the geometrical isomerism such as aspect ratio, planarity, and dipole moment. Thermal parameters of the theoretical calculations revealed that the highest co-planar aromatic core is the most stable conformer.

scholarly journals Defect-Induced Gas-Sensing Properties of a Flexible SnS Sensor under UV Illumination at Room Temperature

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5701
Author(s):  
Nguyen Manh Hung ◽  
Chuong V. Nguyen ◽  
Vinaya Kumar Arepalli ◽  
Jeha Kim ◽  
Nguyen Duc Chinh ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Surface Defects ◽  
Gas Sensing ◽  
Theoretical Calculations ◽  
Tin Sulfide ◽  
Sensing Properties ◽  
Uv Illumination ◽  
Gas Sensing Properties ◽  
Key Factor

Tin sulfide (SnS) is known for its effective gas-detecting ability at low temperatures. However, the development of a portable and flexible SnS sensor is hindered by its high resistance, low response, and long recovery time. Like other chalcogenides, the electronic and gas-sensing properties of SnS strongly depend on its surface defects. Therefore, understanding the effects of its surface defects on its electronic and gas-sensing properties is a key factor in developing low-temperature SnS gas sensors. Herein, using thin SnS films annealed at different temperatures, we demonstrate that SnS exhibits n-type semiconducting behavior upon the appearance of S vacancies. Furthermore, the presence of S vacancies imparts the n-type SnS sensor with better sensing performance under UV illumination at room temperature (25 °C) than that of a p-type SnS sensor. These results are thoroughly investigated using various experimental analysis techniques and theoretical calculations using density functional theory. In addition, n-type SnS deposited on a polyimide substrate can be used to fabricate high-stability flexible sensors, which can be further developed for real applications.

GROWTH OF SUPERCONDUCTING THICK FILMS OF YBaCuO BY SPRAY PYROLYSIS TECHNIQUE AND STUDY OF QUANTUM INTERFERENCE EFFECTS

1989 ◽  
Vol 03 (17) ◽  
pp. 1311-1317 ◽  
Author(s):  
G. S. N. REDDY ◽  
A. K. GUPTA ◽  
V. N. OJHA ◽  
D. K. WALIA ◽  
N. D. KATARIA ◽  
...  
Keyword(s):  
Spray Pyrolysis ◽  
Quantum Interference ◽  
Room Temperature ◽  
Spray Pyrolysis Technique ◽  
Thick Films ◽  
Weak Links ◽  
Superconducting Transition ◽  
Interference Effects ◽  
Superconducting Thick Films ◽  
Made In

Superconducting thick films of YBaCuO are made by spray pyrolysis technique on single crystal SrTiO 3 and MgO substrates. The thickness of the film is about 10 µm. The best film shows T c (R = 0) of the order of 86 K. No marked degradation in superconducting transition temperature is observed when the films are thermally cycled between room temperature and 4.2 K inside a closed liquid helium container. Temperature dependence of the critical current of microbridges fabricated on this film indicates the presence of SNS type weak links. dc SQUID configuration has been made in this film by scribing two bridges in parallel. V - Φ curves show periodic behavior superposed with additional structures.

Room-Temperature Anomalous Coherent Excitonic Optical Stark Effect in Metal Halide Perovskite Quantum Dots

Nano Letters ◽  
2022 ◽  
Author(s):  
Megha Shrivastava ◽  
Franziska Krieg ◽  
Dipendranath Mandal ◽  
Ajay K. Poonia ◽  
Santu K. Bera ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Stark Effect ◽  
Metal Halide ◽  
Metal Halide Perovskite ◽  
Perovskite Quantum Dots ◽  
Optical Stark Effect ◽  
Halide Perovskite

scholarly journals Quantum interference effects at room temperature in OPV-based single-molecule junctions

2013 ◽  
Vol 8 (1) ◽  
Author(s):  
Carlos R Arroyo ◽  
Riccardo Frisenda ◽  
Kasper Moth-Poulsen ◽  
Johannes S Seldenthuis ◽  
Thomas Bjørnholm ◽  
...  
Keyword(s):  
Single Molecule ◽  
Quantum Interference ◽  
Room Temperature ◽  
Interference Effects ◽  
Single Molecule Junctions

Theoretical and Experimental Evaluation of the Effect of Fluorinated Substituent on the Topological Landscape and Thermodynamic Stability of Zeolitic Imidazolate Framework Polymorphs

2018 ◽  
Author(s):  
Mihails Arhangelskis ◽  
Athanassis Katsenis ◽  
Novendra Novendra ◽  
Zamirbek Akimbekov ◽  
Dayaker Gandrath ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Mechanochemical Synthesis ◽  
Thermodynamic Stability ◽  
Experimental Evaluation ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Zeolitic Imidazolate Framework ◽  
Functional Theory ◽  
Calorimetric Measurements ◽  
And Calorimetry

By combining mechanochemical synthesis and calorimetry with theoretical calculations, we demonstrate that dispersion-corrected periodic density functional theory (DFT) can accurately survey the topological landscape and predict relative energies of polymorphs for a previously inaccessible fluorine-substituted zeolitic imidazolate framework (ZIF). Experimental screening confirmed two out of three theoretically anticipated polymorphs, and the calorimetric measurements provided an excellent match to theoretically calculated energetic difference between them.<br>

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

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