Nano-scale chemical reactions based on non-uniform optical near-fields and their applications

Yatsui, Takashi; Yamaguchi, Mas; Nobusada, Katsuyuki

doi:10.1016/j.pquantelec.2017.06.001

Cited by 18 publications

(21 citation statements)

References 100 publications

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“…They feature a large surface to volume ratio and catalyze chemical reactions 4 , including for instance, in atmospheric photochemistry 5,6 . The concentration and enhancement of electromagnetic fields on the nanoscale is important for many applications including detection of trace substances 7 , single-molecule spectroscopy and microscopy 8,9 , as well as nanofocusing and modification of surfaces beyond the optical diffraction limit 10,11 . Isolated nanograins, nanoice, and other nanoparticles are known to play an important role in astrochemistry 12 , enabling the (irradiation-induced) formation of complex molecules and molecular ions 13 .…”

Section: Introductionmentioning

confidence: 99%

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

et al. 2019

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Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.

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Section: Introductionmentioning

confidence: 99%

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

et al. 2019

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“…Although the absorption efficiency was improved by the increase in the electric-field intensity, they continue to require phonon assistance. A direct excitation of Si without phonon assistance is expected to be realized by using the optical near-field (ONF), which is confined in a nano-scale [7][8][9] . Owing to the localization of the optical field at the nano-scale (i.e., a very small value of Δx), large components of wave numbers (a large value of Δk) are generated according to the uncertainty principle ( Fig.…”

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confidence: 99%

Enhanced photo-sensitivity in a Si photodetector using a near-field assisted excitation

et al. 2019

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Silicon is an indispensable material in electric device technology. However, Si is an indirect bandgap material; therefore, its excitation efficiency, which requires phonon assistance, is low under propagating far-field light. To improve the excitation efficiency, herein we performed optical near-field excitation, which is confined in a nano-scale, where the interband transitions between different wave numbers are excited according to the uncertainty principle; thus, optical near-field can directly excite the carrier in the indirect bandgap. To evaluate the effect of optical near-field confined in a nano-scale, we fabricate the lateral Si p-n junction with Au nanoparticles as sources to generate the field confinement. We observed a 47.0% increase in the photo-sensitivity rate. In addition, by using the thin lateral p-n junction, which eliminates the far-field excitation, we confirmed a 42.3% increase in the photosensitivity rate.

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“…Although the photo-excitation of molecular reactions by DUV irradiation can induce molecule reactions at higher yields, excessive irradiation unavoidably causes unintended molecular reactions. To resolve this concern, we utilised the characteristic behaviour of non-uniform ONFs 9 . An ONF is defined as a localised electric field generated around a nano-scaled material 10 , where an induced dipole is generated by light irradiation.…”

Section: Resultsmentioning

confidence: 99%

“…Although the above-described photo-excitation methods have valuable advantages, excessive DUV irradiation will induce some unintended reactions which can damage and break DNA strands due to electronic dissociation 8 . In this paper, we propose a photo-excitation method based on the characteristics of non-uniform optical near-fields (ONFs), which are induced through irradiation by visible light with a much lower optical energy than DUV light 9 . Because contributions from the excited vibrational levels originating from the non-uniform ONFs can compensate for the lack of activation energy for the degradation of DNA strands, we expected the non-uniform ONFs to allow for photo-excitation at a much lower optical energy, thereby avoiding the initiation of any unintended molecular reactions.…”

Section: Introductionmentioning

confidence: 99%

Visible light-induced thymine dimerisation based on large localised field gradient by non-uniform optical near-field

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Yatsui

2019

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The localised excitations of several molecular reactions utilising optical irradiation have been studied in the field of molecular physics. In particular, deoxyribonucleic acid (DNA) strands organise the genetic information of all living matter. Therefore, artificial methods for freely controlling reactions using only light irradiation are highly desirable for reactions of these strands; this in regard with artificial protein synthesis, regional genetic curing, and stochastic analysis of several genetic expressions. Generally, DNA strands have strong absorption features in the deep ultra-violet (DUV) region, which are related to the degradation and reconstruction of the strand bonding structures. However, irradiation by DUV light unavoidably induces unintended molecular reactions which can damage and break the DNA strands. In this paper, we report a photo-induced molecular reaction initiated by the irradiation of DNA strands with visible light. We utilised photo-dissociation from the vibrational levels induced by non-uniform optical near-fields surrounding nanometric Au particles to which DNA strands were attached. The results were experimentally observed by a reduction in the DUV absorbance of the DNA strands during irradiation. There was a much higher yield of molecular reactions than expected due to the absorbance of visible light, and no defects were caused in the DNA strands.

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Nano-scale chemical reactions based on non-uniform optical near-fields and their applications

Cited by 18 publications

References 100 publications

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

Enhanced photo-sensitivity in a Si photodetector using a near-field assisted excitation

Visible light-induced thymine dimerisation based on large localised field gradient by non-uniform optical near-field

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