Laser Scanning-Assisted Tip-Enhanced Optical Microscopy for Robust Optical Nanospectroscopy

Yano, Taka-aki; Tsuchimoto, Yuta; Mochizuki, Masafumi; Hayashi, T.; Hara, Masahiko

doi:10.1177/0003702816652369

Cited by 8 publications

(2 citation statements)

References 16 publications

(27 reference statements)

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“…A variety of solutions for tip drift have been developed, such as atom tracking technique ( 40 ), interferometric detection ( 41 ), and scattering detection ( 42 ), but they are not suitable for combining with the TERS system because of restriction of working environment and samples. We therefore developed our own drift compensation system based on a laser scanning–assisted technique reported previously ( 43 ). Figure 3A shows the concept of our laser scanning–assisted tip drift compensation.…”

Section: Resultsmentioning

confidence: 99%

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers

et al. 2022

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Optical nanoimaging techniques, such as tip-enhanced Raman spectroscopy (TERS), are nowadays indispensable for chemical and optical characterization in the entire field of nanotechnology and have been extensively used for various applications, such as visualization of nanoscale defects in two-dimensional (2D) materials. However, it is still challenging to investigate micrometer-sized sample with nanoscale spatial resolution because of severe limitation of measurement time due to drift of the experimental system. Here, we achieved long-duration TERS imaging of a micrometer-sized WS 2 sample for 6 hours in a reproducible manner. Our ultrastable TERS system enabled to reveal the defect density on the surface of tungsten disulfide layers in large area equivalent to the device scale. It also helped us to detect rare defect-related optical signals from the sample. The present study paves ways to evaluate nanoscale defects of 2D materials in large area and to unveil remarkable optical and chemical properties of large-sized nanostructured materials.

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Section: Resultsmentioning

confidence: 99%

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers

et al. 2022

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“…We constructed a custom-made Raman system with inverted microscope (IX-71, Olympus). 20 He-Ne laser for excitation ( = 632.8 nm, NEO-50MS, NEOARK) was focused onto the sample surfaces through an oil-immersion objective lens (N.A. = 1.35, ©100, Olympus).…”

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Thiol Molecules as Temperature Sensors for Surface-enhanced Raman Scattering Measurements of Heat-sensitive Materials

Mochizuki¹,

Asatyas²,

Suthiwanich³

et al. 2016

Chem. Lett.

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We report a method to establish experimental conditions for surface-enhanced Raman scattering (SERS) spectroscopy in order to avoid thermal damage on heat-sensitive materials by monitoring thermal desorption of thiolate molecules from a metal surface. Thiolate molecules adsorbed on gold desorb at 60100°C, which corresponds to the denaturation or degradation temperature of heat-sensitive materials (e.g. DNA, proteins, polymers, and lipid membranes). By observing the change in Raman signal from the thiolates on SERS substrate, it is possible to estimate the maximum power of excitation laser required for the samples to reach their critical temperatures for thermal degradation. Keywords:Surface-enhanced Raman scattering (SERS) spectroscopy | Temperature sensor | Thiol moleculeSurface-enhanced Raman scattering (SERS) spectroscopy is a powerful nanospectroscopic method to characterize molecular behaviors on metallic particles or nanostructures with ultrahigh sensitivity.13 SERS spectroscopy enables low-destructive and label-free measurements, while maintaining high sensitivity at a single-molecule level.4,5 Thus, SERS has been widely applied to surface-sensitive analyses in various fields such as chemistry, biology, and medicine. 68A significant increase in the local temperature of metallic nanostructures is a critical issue in SERS measurements of heatsensitive materials. 911 The increase in temperature originates mainly from Joule heating induced by enhanced plasmonic electron movements. The increase in temperature depends on several factors (e.g. the degree of plasmonic resonance, power density of the excitation laser, thermal capacity, conductivity of the surrounding medium, etc.). A previous report suggested that the local temperature may increase up to several hundred degrees Celsius during the measurements.12 Therefore, great care should be taken in establishing the experimental conditions for the measurements of heat-sensitive materials. In particular, a precise evaluation of the local temperature of metallic nanostructures is critically important.There are mainly two approaches to evaluate the local temperature: the ratio of Stokes to anti-Stokes Raman intensities of samples 13,14 and the scattering spectra of the metal nanostructures.12 Although these methods are useful for estimating local temperature over a wide range, the accuracy of the temperature evaluated by these approaches is limited to «20°C. In the case of biomolecules, e.g. proteins and double-stranded DNA helices, the critical temperatures for their conformational changes (denaturation and unfolding) are ca. 60°C. 15,16 The range of temperatures, at which conformational changes occur, is within «5°C.15,16 Therefore, there is a high demand for a new approach to evaluate the local temperature with the accuracy of several degrees in Celsius.Herein, we propose a new method for establishing experimental conditions of the laser power density, to avoid thermal damage by monitoring SERS signal from thiols. Temperatures for the thiols to desorb (cleavag...

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Tip-Enhanced Raman Spectroscopy

Umakoshi

Verma

2021

Modern Techniques of Spectroscopy

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Laser Scanning-Assisted Tip-Enhanced Optical Microscopy for Robust Optical Nanospectroscopy

Cited by 8 publications

References 16 publications

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers

Thiol Molecules as Temperature Sensors for Surface-enhanced Raman Scattering Measurements of Heat-sensitive Materials

Tip-Enhanced Raman Spectroscopy

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Laser Scanning-Assisted Tip-Enhanced Optical Microscopy for Robust Optical Nanospectroscopy

Cited by 8 publications

References 16 publications

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS 2 layers

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS 2 layers

Thiol Molecules as Temperature Sensors for Surface-enhanced Raman Scattering Measurements of Heat-sensitive Materials

Tip-Enhanced Raman Spectroscopy

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Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers

Ultrastable tip-enhanced hyperspectral optical nanoimaging for defect analysis of large-sized WS ₂ layers