| 1. |
- Leng, Jian-Cai, et al.
(författare)
-
Orientation of Decanethiol Molecules in Self-Assembled Monolayers Determined by Inelastic Electron Tunneling Spectroscopy
- 2009
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:42, s. 18353-18357
-
Tidskriftsartikel (refereegranskat)abstract
- We present first-principles calculations for the inelastic electron tunneling spectroscopy (IETS) of decanethiolate molecules sandwiched between Au(111) surface and scanning tunneling microscope (STM) reported by Hallback et at, (Nano Left. 2004, 4, 2393). It is demonstrated here that the IET spectra are very sensitive to the molecule-metal contact structure, orientation of the molecule adsorbed on the surface, and the distance between the carbon of the terminal methyl group and the STM tip. With correct assignation of the experimental spectral features, the orientation of the molecule and then the probable configuration of the molecular junction are
|
|
| 2. |
- Lin, Li-Li, et al.
(författare)
-
Determination of the Configuration of a Single Molecule Junction by Inelastic Electron Tunneling Spectroscopy
- 2010
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:11, s. 5199-5202
-
Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations for inelastic electron tunneling spectroscopy (IETS) of a single 1,3-propanedithiol molecule covalently bound to gold electrodes are presented. Inelastic electron tunneling spectra of the single molecule junction with different contact geometries and molecular orientations at the interface are simulated. It is demonstrated that the delicate variation in the configuration of the single molecule junction caused by separating the two electrodes call result in significant changes in the inelastic electron tunneling spectral profile of the junction. The two Most probable configurations of the molecular junction formed in the experiment (Nano Lett. 2008, 8, 1673) are theoretically identified, and the experimental IET spectra are correctly assigned.
|
|
| 3. |
- Lin, Li-Li, et al.
(författare)
-
Effect of Aromatic Coupling on Electronic Transport in Bimolecular Junctions
- 2009
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:32, s. 14474-14477
-
Tidskriftsartikel (refereegranskat)abstract
- We have performed a systematic first-principles study on conductance-voltage characteristics of bioligo(phenylene ethynylene)-monothiol molecular junctions as recently reported by Wu et al.[Nalure Nanotech. 2008, 3, 569]. It is found that the molecular conductance is very sensitive to the vertical distance between two molecules as well as the titled angle between two molecular planes. By comparing with experimental results, key structure parameters for bimolecular junction are determined, indicating that in the experimental devices, the vertical distance between two molecules is around 0.30 mn, the two planar molecules have a cofacial arrangement, and the length of the molecular bridge is about 2.88 nm. The underlying mechanism for electron transport in these aromatically coupled bimolecular junctions has also been discussed.
|
|
| 4. |
- Lin, Li-Li, et al.
(författare)
-
Formation and electronic transport properties of bimolecular junctions based on aromatic coupling
- 2010
-
Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 22:32, s. 325102-
-
Tidskriftsartikel (refereegranskat)abstract
- A systematic first-principles study on conductance-voltage characteristics of bi-(quasi) oligo(phenylene ethynylene)-monothiol molecular junctions reported by Wu et al (2008 Nat. Nanotechnol. 3 569) is presented. The so-called ortho-and para-conformations of the bimolecular junction are considered. Our calculation indicates that the bimolecular junction prefers to take the ortho-conformation because of its lower energy. The simulation supports the experimental findings that aromatic coupling between two molecules is strong enough to induce the formation of molecular junctions. By comparing with experimental results, structure parameters for a probable bimolecular junction are determined. The underlying mechanism for formation of the bimolecular junction and its electron transport is discussed.
|
|
| 5. |
- Ma, Yong, et al.
(författare)
-
Density Functional Theory Study on Raman Spectra of Rhodamine Molecules in Different Forms
- 2014
-
Ingår i: Chinese Journal of Chemical Physics. - : AIP Publishing. - 1674-0068 .- 2327-2244. ; 27:3, s. 291-296
-
Tidskriftsartikel (refereegranskat)abstract
- Rhodamine molecules are one of the most used dyes for applications related to Raman spectroscopy. We have systematically studied Raman spectra of Rhodamine 60, Rhodamine 123, and Rhodamine B (RhB) molecules using density functional theory. It is found that with BP86 functional the calculated Raman spectra of cationic Rhodamine molecules are in good agreement with corresponding experimental spectra in aqueous solution. It is shown that the involvement of the counter ion, chlorine, and the specific hydrogen bonds has noticeable effects on the Raman spectra of RhB that can partially explain the observed difference between Raman spectra of RhB in solution and on gold surfaces. It also indicates that an accurate description of surface enhanced Raman scattering for Rhodamine molecules on metal surface still requires to take into account the changes induced by the interfacial interactions.
|
|
| 6. |
- Ma, Yong, et al.
(författare)
-
Identification of Four C-40 Isomers by Means of a Theoretical XPS/ NEXAFS Spectra Study
- 2018
-
Ingår i: Journal of Physical Chemistry A. - : AMER CHEMICAL SOC. - 1089-5639 .- 1520-5215. ; 122:20, s. 4750-4755
-
Tidskriftsartikel (refereegranskat)abstract
- XPS and NEXAFS spectra of four stable C-40 isomers [29(C-2), 31 (C-s), 38(D-2), and 39(D-sd)] have been investigated theoretically. We combined density functional theory and the full core hole potential method to simulate C 1s XPS and NEXAFS spectra for nonequivalent carbon atoms of four stable C-40 fullerene isomers. The NEXAFS showed obvious dependence on the four C-40 isomers, and XPS spectra are distinct for all four isomers, which can be employed to identify the four stable structures of C-40. Furthermore, the individual components of the spectra according to different categories have been investigated, and the relationship between the spectra and the local structures of C atoms was also explored.
|
|
| 7. |
- Ma, Yong, et al.
(författare)
-
Theoretical N K-edge NEXAFS spectroscopy study for configuration of a dipolar molecule on graphene
- 2018
-
Ingår i: Materials Chemistry and Physics. - : ELSEVIER SCIENCE SA. - 0254-0584 .- 1879-3312. ; 207, s. 309-314
-
Tidskriftsartikel (refereegranskat)abstract
- The landscape of the chromophore-functionalized molecule on graphene surface is of much significance in terms of the application of doped graphene. By means of the N1s near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in density functional theory (DFT), the landscape of a dipolar molecule pyrene-tethered Disperse Red 1 (DRIP) on graphene surface was systematically analyzed. The azo pi* and nitro pi* peaks in experimental spectra were well assigned as the resonances from 1s of N atoms in different compounds to the lowest unoccupied molecular orbital (LUMO). The intensities of the two above peaks are influenced by the incidence angles of X-ray. By comparing the theoretical spectra with the experimental spectra, the most possible geometric configurations of DR1 P molecule on Graphene surface are determined.
|
|
| 8. |
- Song, Xiu-Neng, et al.
(författare)
-
Theoretical Identification of Three C-66 Fullerene Isomers and Related Chlorinated Derivatives by X-ray Photoelectron Spectroscopy and Near-edge X-ray Absorption Fine Structure Spectroscopy
- 2016
-
Ingår i: JOURNAL OF PHYSICAL CHEMISTRY A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 120:50, s. 9932-9940
-
Tidskriftsartikel (refereegranskat)abstract
- C is X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra for three C-66 fullerene isomers and related chlorinated species have been calculated by density functional theory (DFT) method. The XPS spectra show isomer dependence for the three, pristine C-66 isomers but not for the chlorinated species. The NEXAFS spectra exhibit strong dependence on the structures of all the investigated molecules and thus can be well employed to identify the three C-66 fullerene isomers and related chlorinated species. Both XPS and NEXAFS spectra of the chlorinated species present significant variations compared with the pristine fullerenes. The spectral components for carbon atoms of different local environments have been explored as well. The spectra for the carbon atoms connecting to chlorine atoms exhibit a significant blue shift compared to the others.
|
|
| 9. |
- Wang, Guang-Wei, et al.
(författare)
-
Theoretical Isomer Identification of Three C-56 Fullerenes and Their Chlorinated Derivatives by XPS and NEXAFS Spectra
- 2016
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:25, s. 13779-13786
-
Tidskriftsartikel (refereegranskat)abstract
- The C Is X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for three C-56 fullerene isomers and their chlorinated derivatives have been theoretically simulated by means of density functional theory (DFT). Compared with XPS, the NEXAFS spectra present remarkable dependence on the structures of all the studied molecules and thus can be used to identify the three C-56 isomers and chlorinated species. The spectra of the chlorinated species present significant variations compared with the pristine fullerenes. The spectral components of carbon atoms of different local environment have been investigated as well. The spectra of carbons saturated by chlorine atoms exhibit a shift toward higher energies compared with the others.
|
|
| 10. |
- Zou, Bin, et al.
(författare)
-
Effects of field-induced geometry relaxation on the electron transport properties of 4,4'-biphenyldithiol molecular junction
- 2007
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 447:03-jan, s. 69-73
-
Tidskriftsartikel (refereegranskat)abstract
- The non-linear charge transport properties of 4,4 '-biphenyldithiol molecular junction have been studied using the generalized Green's function theory. It is shown that the torsion angle between two phenyls is slightly decreased as increase of the external voltage while the whole molecule moves slightly along the reversed direction of the electric field. Calculations indicate that the inclusion of molecular geometry relaxation can avoid a false prediction of negative differential resistance behavior. The charge redistribution under the external bias results in resistive dipoles inside the molecule. The calculated I-V curves of 4,4 '-biphenyldithiol molecular junction is consistent with experimental observations in some ways.
|
|
