Electronic structures of capped carbon nanotubes under electric fields

Kim, Changwook; Kim, Bongsoo; Lee, Seung Mi; Jo, Chulsu; Lee, Young Hee

doi:10.1103/physrevb.65.165418

Cited by 127 publications

(73 citation statements)

References 27 publications

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“…Accordingly, if the tip is moved towards the sample, first the Ã 1 orbital and then the Ã 2 orbital should be detected, as predicted by theory. At closer distances the electric field of the tip causes the shift of these orbitals to lower energies as reported also for other -conjugated systems [23,24]. Furthermore, the isosurface plots show a location of the Ã 1 orbital direct at the copper surface, explaining that no detection is possible within the current window of experiment.…”

Section: Prl 105 066801 (2010) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 60%

Electronic Mapping of Molecular Orbitals at the Molecule-Metal Interface

et al. 2010

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The molecule-metal interface formed by pyridine-2,5-dicarboxylic acid chemically bonded to the Cu (110) surface is investigated by scanning tunneling microscopy and first-principles calculations. Our current-voltage spectroscopy studies reveal an electronic mapping of molecular orbitals as a function of tip position. By combining experimental and theoretical investigations, individual molecular orbitals are characterized by their energy and spatial distribution. The importance of adsorption geometries and conformational changes on the electron transport properties is highlighted. DOI: 10.1103/PhysRevLett.105.066801 PACS numbers: 73.63.Àb, 31.15.AÀ, 68.37.Ef, 82.37.Gk In the past decade, we have witnessed significant progress in integrating organic molecules in functional molecular devices like single molecule diodes [1,2] or in organic field-effect transistors [3,4]. To improve the functionality of such molecular electronic devices, an essential prerequisite is to gain a substantial understanding of the electronic structure of molecule-surface interfaces near the Fermi level that ultimately controls the performance of such a device [5][6][7].In this context, the precise energetic alignment of the molecular orbitals with respect to the Fermi level of the substrate, in particular, that of the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals, is a key component of the electronic structure of the molecule-surface system under consideration. Therefore, in this Letter we present a detailed electronic mapping of molecular orbitals (MOs) by distance-dependent currentvoltage (I-V) spectroscopy. Combining the spatially resolved scanning tunneling spectroscopy (STS) results with density functional theory (DFT) investigations, we show how to identify the electronic structure of a molecule chemically bonded to a metallic surface. As a model system we investigate the adsorption of the pyridine-2,5-dicarboxylic acid (PyDCAH 2 ) on Cu(110).Our ab initio total-energy calculations have been performed in the framework of DFT [8] by using the PerdewBurke-Ernzerhof [9] exchange-correlation energy functional as implemented in the VASP code [10,11]. A detailed description is available in the supplementary material [12]. We first note that, in the case of the PyDCAH 2 molecule, which adsorbs on the Cu(110) surface under deprotonation of one carboxyl group, forming PyDCAH, several different adsorption geometries must be taken into account due to the presence of a nitrogen atom in the aromatic ring. Therefore, we differentiate in the following between C 7 H 4 N ð2Þ O 4 , describing a PyDCAH molecule with the nitrogen on position two in the ring (counting the ring atoms from the carbon atom located at the bonded carboxylate unit), and C 7 H 4 N ð3Þ O 4 , denoted as configuration f1g and f2g, respectively. Experimentally, there is no possibility to influence the orientation of the molecule during the adsorption process or to monitor topographically which configuration is preferentially adsorbed. If the ...

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Section: Prl 105 066801 (2010) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 60%

Electronic Mapping of Molecular Orbitals at the Molecule-Metal Interface

et al. 2010

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“…The Fermi level energy is approximately middle of energy gap and work function is defined as the energy difference between the Fermi level energy and the LUMO [11] which is important in field emission applications. For the configuration, the Fermi level energy (E FL ) is increased from -4.49 eV in the Table 1 Adsorption energy of acetone on Al 12 N 12 (E ad ), HOMO energies (E HOMO ), LUMO energies (E LUMO ), HOMO-LUMO energy gap (E g ), Fermi level energy (E FL ), and work function (U) for the pristine and acetone/Al 12 N 12 complexes.…”

Section: Resultsmentioning

confidence: 99%

Al12N12 nanocage as potential adsorbent for removal of acetone from environmental systems

et al. 2014

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The electronic and geometrical structures of acetone adsorption on Al 12 N 12 nanocage have been investigated using DFT calculations, by means of B3LYP functional with 6-31G* and 6-31 ? G*basis sets. The results showed that the acetone binds to the Al atom of Al 12 N 12 with adsorption enthalpies of -119.12 kJ/mol (6-31G* basis set) and about -116.94 kJ/mol (6-31 ? G* basis set) for the first acetone and -116.57 kJ/mol (6-31G* basis set) and about -113.89 kJ/mol (6-31 ? G* basis set) for the second one (per each molecule). On the basis of calculated density of states, adsorption of acetone molecule on the Al 12 N 12 surface induces some changes in electronic properties of the nanocage. For the systems, the field emission properties are improved upon the acetone adsorption and the thermodynamic values indicated that this process is exothermic. On the basis of the results, Al 12 N 12 nanocage can be a promising candidate for adsorption of acetone from environmental systems.

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“…The work function is defined as the energy difference between the Fermi level energy and the LUMO. 15 For the configurations, work function is decreased from 3.43 eV in the pristine B 12 N 12 nanocage to 3.30, 3.26, and 3.09 eV in configurations A, B, and C, respectively ( Table 1). The results show that the field emission properties of the configurations are facilitated upon urea adsorption.…”

Section: Resultsmentioning

confidence: 99%

Adsorption of the urea molecule on the B$_{12}$N$_{12}$ nanocage

Baei¹

2014

Turk J Chem

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Abstract:The adsorption of the urea molecule on the external surface of the B 12 N 12 nanocage was investigated using density functional theory (DFT) calculations. Adsorption of urea on the nanocage releases energies of about -23.70to -29.50 kcal/mol with a significant NBO charge transfer from the urea to the nanocage. It was also found that the urea molecule can be strongly chemisorbed on the surface of the nanocage with Gibbs free energies of − 7.91 to − 14.81 kcal/mol. The HOMO-LUMO gap of the nanocage does not change significantly upon urea adsorption, while the Fermi level is dramatically changed from − 4.27 eV in the pristine nanocage to upper energies upon urea adsorption. The geometric structure, adsorption energy, solvation effect, charge transfer, and frequency analyses of the urea adsorption on the nanocage models showed that the urea molecule could be firmly adsorbed by the nanocage and the nanocage could be a potential efficient adsorbent for the adsorption of urea.

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Electronic structures of capped carbon nanotubes under electric fields

Cited by 127 publications

References 27 publications

Electronic Mapping of Molecular Orbitals at the Molecule-Metal Interface

Electronic Mapping of Molecular Orbitals at the Molecule-Metal Interface

Al12N12 nanocage as potential adsorbent for removal of acetone from environmental systems

Adsorption of the urea molecule on the B$_{12}$N$_{12}$ nanocage

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