Photo-induced force for spectroscopic imaging at the nanoscale

Jahng, Junghoon; Ladani, Faezeh Tork; Khan, Ryan Muhammad; Potma, Eric O.

doi:10.1117/12.2208199

Cited by 12 publications

(13 citation statements)

References 8 publications

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“…The spectral dependence of the force follows the dispersive part of the polarizability. The latter is expected when the tip polarizability is dominated by α t [22], which is the case in this spectral range. This situation is relevant to actual experimental settings, as is reported in [14].…”

Section: Photo-induced Force Between a Tip And A Nanoparticlementioning

confidence: 71%

“…Simple analytical models based on the dipolar approx-arXiv:1701.02390v1 [physics.optics] 9 Jan 2017 imation of the tip's polarizability offer clear insights into the behavior of the photo-induced force exerted on the tip [3,11,[20][21][22]. In particular, dipole-dipole based tipsample interactions predict a distance dependent gradient and scattering force that closely resembles experimental observations [16,17].…”

Section: Introductionmentioning

confidence: 85%

“…In this Section, we present calculations of the photoinduced force for several typical experimental geometries that are relevant to PiFM imaging [22]. First, we will consider the photo-induced force exerted on the tip over a bare glass substrate.…”

Section: Behavior Of the Photo-induced Forcementioning

confidence: 99%

“…The observed distance dependence of the force mimics the interaction between the tip dipole and its image in the substrate. The latter scenario in PiFM is usually referred to as the image dipole force, which, using a simple analytical model based on dipole-dipole interaction, results in a ∼ z −4 dependence for the gradient force when only the E z component of the field is considered [22]. Our formalism includes all field components and generalizes the force for different illumination conditions.…”

Section: A Photo-induced Force Over a Glass Substratementioning

confidence: 99%

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Dyadic Green's function formalism for photoinduced forces in tip-sample nanojunctions

Ladani

Potma

2017

Phys. Rev. B

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A comprehensive theoretical analysis of photo-induced forces in an illuminated nanojunction, formed between an atomic force microscopy tip and a sample, is presented. The formalism is valid within the dipolar approximation and includes multiple scattering effects between the tip, sample and a planar substrate through a dyadic Green's function approach. This physically intuitive description allows a detailed look at the quantitative contribution of multiple scattering effects to the measured photo-induced force, effects that are typically unaccounted for in simpler analytical models. Our findings show that the presence of the planar substrate and anisotropy of the tip have a substantial effect on the magnitude and the spectral response of the photo-induced force exerted on the tip. Unlike previous models, our calculations predict photo-induced forces that are within range of experimentally measured values in photo-induced force microscopy (PiFM) experiments.PACS numbers: May be entered using the \pacs{#1} command.

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Section: Photo-induced Force Between a Tip And A Nanoparticlementioning

confidence: 71%

Section: Introductionmentioning

confidence: 85%

Section: Behavior Of the Photo-induced Forcementioning

confidence: 99%

Section: A Photo-induced Force Over a Glass Substratementioning

confidence: 99%

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Dyadic Green's function formalism for photoinduced forces in tip-sample nanojunctions

Ladani

Potma

2017

Phys. Rev. B

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“…where H is the Hamaker constant, R is the tip radius, and z is the distance between the tip's apex and the sample surface. The magnitude of the photo-induced gradient force depends on the β parameter, which is defined as β = 3 Re{α * t α p }E 2 0z /2πε 0 , where E 0z is the z-component of the incident field, α t and α p are the complex polarizability of the tip and the molecule respectively 29 . The scattering force F sc is regarded as a constant in the nearfield region.…”

Section: Amplitude-distance Simulationsmentioning

confidence: 99%

Quantitative analysis of sideband coupling in photoinduced force microscopy

et al. 2016

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We present a theoretical and experimental analysis of the cantilever motions detected in photoinduced force microscopy (PiFM) using the sideband coupling detection scheme. In sideband coupling, the cantilever dynamics are probed at a combination frequency of a fundamental mechanical eigenmode and the modulation frequency of the laser beam. Using this detection mode, we develop a method for reconstructing the modulated photo-induced force gradient from experimental parameters in a quantitative manner. We show evidence, both theoretically and experimentally, that the sideband coupling detection mode provides PiFM images with superior contrast compared to images obtained when detecting the cantilever motions directly at the laser modulation frequency.

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Near‐Field Nano‐Optical Imaging of van der Waals Materials

Kwon

Kim

Pei-wen

et al. 2023

Advanced Physics Research

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Abstract2D van der Waals (vdW) materials are emerging as the next generation platform for optical and electronic devices with their wide coverage of the energy bandgaps. The strong light–matter interactions in 2D vdW layers allow for exploring novel optical and electronic phenomena such as 2D polaritons exhibiting ultrahigh field confinement, defects‐induced new quantum states, and strain‐modulated quantum confinement of 2D excitons. Far‐field optical imaging techniques are extensively used to characterize the 2D vdW materials so far, however, subdiffraction spatial resolution is required for comprehensive investigations of 2D vdW materials of which physical properties are greatly influenced by local defects and strain. This article aims to cover historical advances, fundamental principles, and distinct features of emerging near‐field optical imaging techniques: scattering‐type scanning near‐field optical microscopy, tip‐enhanced Raman spectroscopy, tip‐enhanced photoluminescence techniques, and photo‐induced force microscopy. The recent developments toward spectroscopic analysis of near‐field imaging and applications for unveiling unique properties of 2D polaritons, nanoscale defects, and mechanical strains in 2D vdW materials, are also discussed. This review article provides an understanding of emerging near‐field imaging techniques and suggests prospective applications for exploring 2D vdW materials.

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Photo-induced force for spectroscopic imaging at the nanoscale

Cited by 12 publications

References 8 publications

Dyadic Green's function formalism for photoinduced forces in tip-sample nanojunctions

Dyadic Green's function formalism for photoinduced forces in tip-sample nanojunctions

Quantitative analysis of sideband coupling in photoinduced force microscopy

Near‐Field Nano‐Optical Imaging of van der Waals Materials

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