| 1. |
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| 2. |
- Cao, Hui, et al.
(författare)
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Temperature-dependent statistical behavior of single molecular conductance in aqueous solution
- 2008
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 130:21, s. 6674-
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Tidskriftsartikel (refereegranskat)abstract
- We have combined molecular dynamics simulations with first principles calculations to study electron 4 transport in a single molecule of perylene tetracarboxylic diimide (PTCDI) sandwiched between two gold electrodes with an aqueous electrolyte. This combination has for the first time allowed one to reveal statistical behavior of molecular conductance in solution at different temperatures and to produce conductance histograms that can be directly compared with experiments. Our calculations show that experimentally observed temperature-dependent conductance ran be attributed to the thermal effect on the hydrogen bonding network around the molecule and can be described by the radial distribution of water molecules surrounding the oxygen atom in the PTCDI molecule.
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| 3. |
- Duan, Sai, et al.
(författare)
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Optomagnetic Effect Induced by Magnetized Nanocavity Plasmon
- 2019
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 141:35, s. 13795-13798
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new type of optomagnetic effect induced by a highly confined plasmonic field in a nanocavity. It is shown that a very large dynamic magnetic field can be generated as the result of the inhomogeneity of nanocavity plasmons, which can directly activate spin-forbidden transitions in molecules. The dynamic optomagnetic effects on optical transitions between states of different spin multiplicities are illustrated by first-principles calculations for C-60. Remarkably, the intensity of spin forbidden singlet-to-triplet transitions can even be stronger than that of singlet-to-singlet transitions when the spatial distribution of plasmon is comparable with the molecular size. This approach not only offers a powerful optomagnetic means to rationally fabricate molecular excited states with different multiplicities but also provides a groundbreaking concept of the light-matter interaction that could lead to the observation of new physical phenomena and the development of new techniques.
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| 4. |
- Duan, Sai, et al.
(författare)
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Theoretical Modeling of Plasmon-Enhanced Raman Images of a Single Molecule with Subnanometer Resolution
- 2015
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 137:30, s. 9515-9518
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Tidskriftsartikel (refereegranskat)abstract
- Under local plasmonic excitation, Raman images of single molecules can now surprisingly reach subnanometer resolution. However, its physical origin has not been fully understood. Here we report a quantum-mechanical description of the interaction between a molecule and a highly confined plasmonic field. We show that When the spatial distribution of the plasmonic field is comparable to the size of the molecule, the optical transition matrix of the molecule becomes dependent on the position and distribution of the plasmonic field, resulting in a spatially resolved high-resolution Raman image of the molecule. The resonant Raman image reflects the electronic transition density of the molecule. In combination with first-principles calculations, the simulated Raman linage of a porphyrin derivative adsorbed on a silver surface nicely reproduces its experimental counterpart. The present theory provides the basic framework for describing linear and nonlinear responses of molecules under highly confined plasmonic fields.
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| 5. |
- Ji, Yongfei, et al.
(författare)
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New Mechanism for Photocatalytic Reduction of CO2 on the Anatase TiO2(101) Surface : The Essential Role of Oxygen Vacancy
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:49, s. 15896-15902
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Tidskriftsartikel (refereegranskat)abstract
- Photocatalytic reduction of CO2 into organic molecules is a very complicated and important reaction. Two possible pathways, the fast-hydrogenation (FH) path and the fast-deoxygenation (FdO) path, have been proposed on the most popular photocatalyst TiO2. We have carried out first-principles calculations to investigate both pathways on the perfect and defective anatase TiO2(101) surfaces to provide comprehensive understanding of the reaction mechanism. For the FH path, it is found that oxygen vacancy on defective surface can greatly lower the barrier of the deoxygenation processes, which makes it a more active site than the surface Ti. For the FdO path, our calculation suggests that it can not proceed on the perfect surface, nor can it proceed on the defective surface due to their unfavorable energetics. Based on the fact that the FH path can proceed both at the surface Ti site and the oxygen vacancy site, we have proposed a simple mechanism that is compatible with various experiments. It can properly rationalize the selectivity of the reaction and greatly simplify the picture of the reaction. The important role played by oxygen vacancy in the new mechanism is highlighted and a strategy for design of more efficient photocatalysts is proposed accordingly.
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| 6. |
- Li, Zhenyu, et al.
(författare)
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How Graphene is Cut upon Oxidation?
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:18, s. 6320-6321
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Tidskriftsartikel (refereegranskat)abstract
- Our first principles calculations reveal that an oxidative cut of graphene is realized by forming epoxy and then carbonyl pairs. Direct formation of a carbonyl pair to tear graphene up from an edge position is not favorable in energy. This atomic picture is valuable for developing effective means of graphene manipulation. The proposed epoxy pairs may be related to some long puzzling experimental observations on graphene oxide.
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| 7. |
- Luo, Yi, et al.
(författare)
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Visualizing the Entire Range of Noncovalent Interactions in Nanocrystalline Hybrid Materials Using 3D Electron Diffraction
- 2022
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:24, s. 10817-10824
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Tidskriftsartikel (refereegranskat)abstract
- Noncovalent interactions are essential in the formation and properties of a diverse range of hybrid materials. However, reliably identifying the noncovalent interactions in nanocrystalline materials remains challenging using conventional methods such as X-ray diffraction and spectroscopy. Here, we demonstrate that accurate atomic positions including hydrogen atoms can be determined using three-dimensional electron diffraction (3D ED), from which the entire range of noncovalent interactions in a nanocrystalline aluminophosphate hybrid material SCM-34 are directly visualized. The protonation states of both the inorganic and organic components in SCM-34 are determined from the hydrogen positions. All noncovalent interactions, including hydrogen-bonding, electrostatic, π–π stacking, and van der Waals interactions, are unambiguously identified, which provides detailed insights into the formation of the material. The 3D ED data also allow us to distinguish different types of covalent bonds based on their bond lengths and to identify an elongated terminal P═O π-bond caused by noncovalent interactions. Our results show that 3D ED can be a powerful tool for resolving detailed noncovalent interactions in nanocrystalline materials. This can improve our understanding of hybrid systems and guide the development of novel functional materials.
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| 8. |
- Luo, Zhixun, et al.
(författare)
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Photoassisted Magnetization of Fullerene C-60 with Magnetic-Field Trapped Raman Scattering
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:2, s. 1130-1135
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Tidskriftsartikel (refereegranskat)abstract
- We report a photoassisted method to magnetize microcrystal fullerene C-60 at room temperature by exciting it to triplet states via a proper laser radiation and then trapping the spin-polarized states under a strong magnetic field. Novel changes on Raman scattering of the C-60 microcrystals were observed in the presence and absence of the magnetic field. In particular, the Raman spectra were found to exhibit a "hysteresis" phenomenon when the external magnetic field was removed. In light of this, we propose magnetic-field-trapped Raman spectroscopy (MFTRS) and employ first-principle calculations to reproduce the Raman activities of C-60 at different states. Further, MFTRS of the fullerene is demonstrated to originate from its photoassisted magnetization (PAM). The PAM strategy enables the magnetization of materials which consist of only light elements; meanwhile, the MFTRS investigation may open a new research field in Raman spectroscopy.
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| 9. |
- Triguero, L., et al.
(författare)
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Direct experimental measurement of donation/back-donation in unsaturated hydrocarbon bonding to metals
- 2000
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 122:49, s. 12310-12316
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Tidskriftsartikel (refereegranskat)abstract
- Using resonant and off-resonant X-ray emission spectroscopy, in combination with ground-state density functional calculations, we examine the electronic structure of chemisarbed ethylene and benzene on thr Cu(110) surface to investigate the suitability of the donation/back-donation bonding model given by Dewar(1) and Chart and Duncanson(2) (DCD) for the interaction of unsaturated hydrocarbons with metal surfaces. We give an experimental verification of the DCD model and find donation/back-donation to be twice as large for ethylene as for benzene. In particular, the degree of sigma-pi mixing (rehybridization) is found to correspond to the amount of donation/back-donation, which is put in relation to the aromatic and nonaromatic pi characters of benzene and ethylene, respectively.
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| 10. |
- Triguero, L, et al.
(författare)
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Direct experimental measurement of donation/back-donation in unsaturated hydrocarbon bonding to metals
- 2000
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Ingår i: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - : AMER CHEMICAL SOC. - 0002-7863. ; 122:49, s. 12310-12316 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- Using resonant and off-resonant X-ray emission spectroscopy, in combination with ground-state density functional calculations, we examine the electronic structure of chemisarbed ethylene and benzene on thr Cu(110) surface to investigate the suitability of
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