Theoretical Analysis of Optical Absorption Spectra of Parallel Nanowire Dimers and Dolmen Trimers

Pandeya, Pratima; Aikens, Christine M.

doi:10.1021/acs.jpcc.0c04419

Cited by 6 publications

(34 citation statements)

References 110 publications

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“…This weak perturbation leads to a red shift for the first excitation in HTH reminiscent of a J-aggregate type dipole–dipole interaction along the z -axis and a red or blue shift for excitations in SBS reminiscent of either a J- or H-aggregate type interaction along the x - and y -axes. Similar results have been reported in a previous study . These excitations in particular were consistently found to involve collective, in-phase combinations of molecular orbital transitions within each wire; therefore, they can also be identified as molecular plasmonic excitations.…”

Section: Resultssupporting

confidence: 89%

“…Similar results have been reported in a previous study. 53 These excitations in particular were consistently found to involve collective, in-phase combinations of molecular orbital transitions within each wire; therefore, they can also be identified as molecular plasmonic excitations. 2, transition rate heat maps induced by external point charge for selected excitations in the HTH and SBS orientations with different separation distances were calculated and are plotted in Figure 5.…”

Section: Resultsmentioning

confidence: 99%

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Electron-Beam-Induced Molecular Plasmon Excitation and Energy Transfer in Silver Molecular Nanowires

Lingerfelt

Jakowski

et al. 2021

J. Phys. Chem. A

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We investigate (1) electron-beam-induced plasmon absorption spectra of Ag molecular nanowire dimers and (2) electron-beam-induced energy transfer between two nanowires. We employ linear-response time-dependent density functional theory (TDDFT) and real-time TDDFT methods to simulate the electronbeam-induced plasmonic excitations, dynamics, and corresponding electron energy loss spectrum for small models of a single molecular nanowire with four Ag atoms and for two Ag nanowires. An array of different relative orientations of nanowires and of different initial excitation conditions resulting from applying an electron beam at different positions with respect to the Ag nanowires is investigated. The results demonstrate (1) an electron beam can induce plasmonic excitations from the molecular Ag nanowire ground state to the excited states that are both optically allowed and forbidden, (2) a tunability for selective excitations that can be controlled by the position of a focused electron beam, and (3) kinetic and dynamic behaviors of time-dependent electron-beam-induced energy transfer between two Ag molecular nanowires depend on the position of the beam source and nanowire separation distance, providing insights into the spatial dependences of plasmonic couplings in nanowire arrays.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Electron-Beam-Induced Molecular Plasmon Excitation and Energy Transfer in Silver Molecular Nanowires

Lingerfelt

Jakowski

et al. 2021

J. Phys. Chem. A

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“…We focus on the prototypical system of linear Ag n nanowire tips interacting with the CO 2 molecule. Ag n nanowires have been widely used as prototypical systems for studies of plasmonics-related properties. − The nanowires have a strong longitudinal absorption peak that decreases in energy with increasing length, , allowing us to readily study size dependence. CO 2 was selected because it has both a Raman-active symmetric stretching mode (1307 cm –1 at the BP86/cc-pVDZ level) and a Raman-inactive asymmetric stretching mode (2359 cm –1 ).…”

Section: Resultsmentioning

confidence: 99%

Quantum Mechanical Effects in High-Resolution Tip-Enhanced Raman Imaging

Gieseking

2022

J. Phys. Chem. C

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Tip-enhanced Raman spectroscopy (TERS) with atomically sharp tips can achieve subnanometer spatial resolution due to confinement of the plasmonic electric field. Although enhancement of the local electromagnetic field is generally the dominant enhancement mechanism, chemical interactions may substantially modify the TERS intensity on the subnanometer scale. Modeling these chemical interactions requires a quantum mechanical treatment of both the molecule and the metal tip. The semiempirical INDO/CIS model reproduces the TD-DFT optical spectra of Ag nanoclusters and allows straightforward decomposition of the TERS enhancement into electromagnetic and chemical contributions. In a prototypical Ag n nanowire−CO 2 system, we show that chemical interactions on a subnanometer scale substantially modify the TERS intensity, suppressing the signal of the Raman-active stretching mode and enhancing the signal of the Raman-inactive mode. The enhancement profile in the TERS images results from changes in three distinct factors: (1) the effective electric field on the nanowire, (2) the extent of ground-state charge transfer, and (3) the extent of mixing between σ-type and π-type molecular orbitals due to symmetry-breaking. These results suggest that a subtle interplay between several quantum mechanical effects are critical to understand the origins of TERS images on the subnanometer scale.

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“…Plasmonic coupling is a phenomenon that occurs when two or more plasmonic nanoparticles come into close proximity, greatly affecting the optical characteristics of the nanoparticles. − A nanoparticle dimer system is the simplest situation in which to witness this effect. Silver nanowire dimer systems exhibit absorption spectra with coupled longitudinal and transverse mode excitations. − Recent research in this field has employed time-dependent density functional theory (TDDFT) ,,,− and approximate TDDFT approaches ,, in dimer systems to examine their optical properties from a theoretical perspective.…”

Section: Introductionmentioning

confidence: 99%

Effects of Static Electric Fields on the Excitations of Silver Nanowire Dimers

Samarasinghe,

Aikens

2024

J. Phys. Chem. A

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We theoretically studied the introduction of static electric fields to Ag 10 nanowire dimer systems, including the effects of this field on optical absorption characteristics and the orbitals responsible for these excitations. Linear-response time-dependent density functional theory computations were performed on three distinct dimer systems: end-to-end, parallel, and 90°angle dimer systems separated by a closest interparticle distance of 7.0 Å. The calculations were performed in the presence of a 0.1 V/Å electric field strength applied in the z and y directions. The orientation of the dimer system and the direction of the applied static electric field each play a significant role in the resulting absorption spectra and the electronic structure of the nanowires. As a result, a dimer system can exhibit a blue shift for the longitudinal excitation and a red shift for the transverse excitation in the presence of one direction of the static electric field but not for the other direction. Notably, the electron density shifts from one nanowire to the other in the presence of the static electric field. Changes in optical characteristics and electronic structure suggest that the usage of a static electric field with a particular spatial configuration of nanowires provides a way to tune the optical properties of the system.

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Theoretical Analysis of Optical Absorption Spectra of Parallel Nanowire Dimers and Dolmen Trimers

Cited by 6 publications

References 110 publications

Electron-Beam-Induced Molecular Plasmon Excitation and Energy Transfer in Silver Molecular Nanowires

Electron-Beam-Induced Molecular Plasmon Excitation and Energy Transfer in Silver Molecular Nanowires

Quantum Mechanical Effects in High-Resolution Tip-Enhanced Raman Imaging

Effects of Static Electric Fields on the Excitations of Silver Nanowire Dimers

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