| 1. |
- Yuan, Zhe, 1981, et al.
(författare)
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Symmetry-dependent screening of surface plasmons in ultrathin supported films: The case of Al/Si(111)
- 2011
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Ingår i: Physical Review B. - 1098-0121. ; 83:16
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Tidskriftsartikel (refereegranskat)abstract
- A joint theoretical and experimental study of plasmon excitations for Al overlayers on Si(111) has been carried out. The presence of the substrate is found to drastically modify the hybridization and charge density response of the surface plasmons of the metal overlayers. The symmetric mode, which is polarized toward the Al/Si interface, is strongly damped in intensity and significantly redshifted in energy. However, the antisymmetric mode, which is polarized to the metal-vacuum interface, is essentially unaffected by the presence of the substrate. A low-energy acoustic plasmon mode is also found in a one monolayer Al film and is almost unaffected by the substrate. The calculated plasmon dispersions with substrate are in good agreement with experimental data measured by electron energy loss spectroscopy. Our results suggest that interaction and screening at the subnanometer scale are symmetry dependent, a conclusion that may have general implications in other thin films and related structures.
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| 2. |
- Fang, Yurui, 1983, et al.
(författare)
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Plasmon Enhanced Internal Photoemission in Antenna-Spacer-Mirror Based Au/TiO2 Nanostructures
- 2015
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 15:6, s. 4059-4065
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Tidskriftsartikel (refereegranskat)abstract
- Emission of photoexcited hot electrons from plasmonic metal nanostructures to semiconductors is key to a number of proposed nanophotonics technologies for Solar harvesting, water splitting, photocatalysis, and a variety of optical sensing and photodetector applications. Favorable materials and catalytic properties make systems based on gold and TiO2 particularly interesting, but the internal photo emission efficiency for visible light is low because of the wide bandgap of the semiconductor. We investigated the incident photon-to-electron conversion efficiency of thin TiO2 films decorated with Au nanodisk antennas in an electrochemical circuit and found that incorporation of a Au mirror beneath the semiconductor amplified the photoresponse for light with wavelength lambda = 500-950 nm by a factor 2-10 compared to identical structures lacking the mirror component. Classical electrodynamics simulations showed that the enhancement effect is caused by a favorable interplay between localized surface plasmon excitations and cavity modes that together amplify the light absorption in the Au/TiO2 interface. The experimentally determined internal quantum efficiency for hot electron transfer decreases monotonically with wavelength, similar to the probability for interband excitations with energy higher than the Schottky barrier obtained from a density functional theory band structure simulation of a thin Au/TiO2 slab.
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| 3. |
- Gao, Yi, et al.
(författare)
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Semiclassical approach to plasmon-electron coupling and Landau damping of surface plasmons
- 2011
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Ingår i: The Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 134:13
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Tidskriftsartikel (refereegranskat)abstract
- A semiclassical model is developed to describe plasmon–electron coupling and electronic damping of surface plasmons. It is compared with the ab initio linear response calculations for metallic thin films in the jellium approximation and for a realistic crystalline Mg(0001) surface. The semiclassical model is able to reproduce the quantum oscillations of plasmon linewidth, which was obtained in the previous ab initio calculations. In addition, state-resolved analysis reveals the origin of these oscillations, which result from superposition of the short-period oscillations of individual electron–hole pair transitions. The semiclassical model is further applied to a crystalline Mg(0001) surface, where linewidth dispersion of the surface plasmon is calculated and shows good agreement with earlier ab initio calculation and experiment. Our results suggest that this semiclassical approach is quite promising for the quantitative description of plasmon–electron coupling and associated processes such as surface-enhanced Raman scattering, light emission, and fluorescence.
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| 4. |
- Jiao, Yang, 1985, et al.
(författare)
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Schottky barrier formation and band bending revealed by first- principles calculations
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 5, s. Art. no. 11374-
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Tidskriftsartikel (refereegranskat)abstract
- The formation of a Schottky barrier at the metal-semiconductor interface is widely utilised in semiconductor devices. With the emerging of novel Schottky barrier based nanoelectronics, a further microscopic understanding of this interface is in high demand. Here we provide an atomistic insight into potential barrier formation and band bending by ab initio simulations and model analysis of a prototype Schottky diode, i.e., niobium doped rutile titania in contact with gold (Au/Nb:TiO2). The local Schottky barrier height is found to vary between 0 and 1.26 eV depending on the position of the dopant. The band bending is caused by a dopant induced dipole field between the interface and the dopant site, whereas the pristine Au/TiO2 interface does not show any band bending. These findings open the possibility for atomic scale optimisation of the Schottky barrier and light harvesting in metal-semiconductor nanostructures.
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| 5. |
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| 6. |
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| 7. |
- Bao, Q. X., et al.
(författare)
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Hydrogen adsorption on Ti containing organometallic structures grafted on silsesquioxanes
- 2010
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Ingår i: Structural Chemistry. - : Springer Science and Business Media LLC. - 1040-0400 .- 1572-9001. ; 21:5, s. 1111-1116
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of hydrogen molecule on a novel structure of Ti containing organometallic complexes grafted on silsequioxanes (SQ, H8Si8O12) was investigated by means of DFT method. The hydrogen adsorption properties of the complex structures TiRH7Si8O12 (R = C4H3, C5H4, C6H5) keep almost the same as that of corresponding Ti containing organometallic complexes. Moreover, these complex structures can avoid the problem of transition metal clustering which is a disadvantage for hydrogen adsorption. The maximum number of hydrogen molecules adsorbed was still determined by 18 electron rule, that is to say 5, 4, and 4 H-2 molecules for TiRH7Si8O12 with R = C4H3, C5H4, and C6H5, respectively. At the same time, all the average binding energy of H-2 is located in 0.2-1.0 eV, which is an advantage for hydrogen storage at ambient conditions. Therefore, the materials studied here may provide some enlightenment for developing new types of hydrogen storage materials.
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| 8. |
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| 9. |
- Gao, Shiwu, 1963, et al.
(författare)
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Emergence of collective plasmon excitation in a confined one-dimensional electron gas
- 2005
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Ingår i: PHYSICAL REVIEW B. ; 72:12, s. art. no. 121406-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the electronic excitation in a confined one-dimensional electron gas, which is utilized to model atomic chains created in recent experiments. The length dependence of the excitation spectra is obtained from the linear response theory within the random phase approximation and time-dependent density functional theory. As the length of the chains increases, the dipole excitation spectra show a transition from electron-hole pair excitations to collective plasmon excitation. The trend of the length-dependent plasmon resonance is predicted, and the nature of the plasmon resonance is also elaborated.
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| 10. |
- Gao, Shiwu, 1963
(författare)
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Water Adsorption on Na/Cu(111): State-Specific Coupling with Quantum Well States
- 2012
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:33, s. 17613-17618
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of water molecules on sodium-covered Cu(111) surfaces have been studied using first-principles calculations. Water molecules interact predominantly with the quantum well states of the Na overlayers, leading to charge transfer and reduction of the dissociation barrier. This interaction is state specific. At one monolayer Na coverage, the water molecule shows a maximum ratio between the adsorption energy and dissociation barrier, favoring the catalytic water splitting reaction. This conclusion is in accord with experimental observation and suggests the possibility for state-selective control of water–surface interactions.
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