Surface heating by optical beams and application to mid-infrared imaging

Haché, Alain; Anh, Phuong; Bonora, Stefano

doi:10.1364/ao.51.006578

Cited by 11 publications

(5 citation statements)

References 13 publications

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“…The difference in Seebeck coefficient ∆S = S 2 − S 1 = 2 µV/K is displayed in figure 1(c). Here the temperature distribution is assumed to have a Gaussian shape (see [23] and SI) and we convolute each line of the Seebeck map with the temperature distribution to obtain the thermovoltage map. As can be seen in figure 1(d), the resulting thermovoltage signal is positive along the position of the junction where the BLG changes to SLG, reproducing the experimentally observed results well.…”

Section: Resultsmentioning

confidence: 99%

Direct mapping of local Seebeck coefficient in 2D material nanostructures via scanning thermal gate microscopy

et al. 2020

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Studying local variations in the Seebeck coefficient of materials is important for understanding and optimizing their thermoelectric properties, yet most thermoelectric measurements are global over a whole device or material, thus overlooking spatial divergences in the signal and the role of local variation and internal structure. Such variations can be caused by local defects, metallic contacts or interfaces that often substantially influence thermoelectric properties, especially in two dimensional materials. Here, we demonstrate scanning thermal gate microscopy, a non-destructive method to obtain high resolution 2-dimensional maps of the thermovoltage, to study graphene samples. We demonstrate the efficiency of this newly developed method by measuring local Seebeck coefficient in a graphene ribbon and in a junction between single-layer and bilayer graphene.

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Section: Resultsmentioning

confidence: 99%

Direct mapping of local Seebeck coefficient in 2D material nanostructures via scanning thermal gate microscopy

et al. 2020

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“…Here the temperature distribution is assumed to have a Gaussian shape see ( [22] and SI) and we convolute each line of the Seebeck map with the temperature distribution to obtain the thermovoltage map. As can be seen in Figure 1d, the resulting thermovoltage signal is positive along the position of the junction where the BLG changes to SLG, reproducing the experimentally observed results well.…”

Section: Resultsmentioning

confidence: 99%

Direct Mapping of Local Seebeck Coefficient in 2D Material Nanostructures via Scanning Thermal Gate Microscopy

Harzheim,

Evangeli,

Kolosov

et al. 2020

Preprint

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Local variations in the Seebeck coecient in low-dimensional materials-based nanostructures and devices play a major role in their thermoelectric performance. Unfortunately, currently most thermoelectric measurements probe the aggregate characteristics of the device as a whole, failing to observe the effects of the local variations and internal structure. Such variations can be caused by local defects, geometry, electrical contacts or interfaces and often substantially influence thermoelectric properties, most profoundly in two-dimensional (2D) materials. Here, we use Scanning Thermal Gate Microscopy (STGM), a non-invasive method not requiring an electrical contact between the nanoscale tip and the probed sample, to obtain nanoscale resolution 2D maps of the thermovoltage in graphene samples. We investigate a junction formed between single-layer and bilayer graphene and identify the impact of internal strain and Fermi level pinning by the contacts using a deconvolution method to directly map the local Seebeck coefficient. The new approach paves the way for an in-depth understanding of thermoelectric behaviour and phenomena in 2D materials nanostructures and devices.

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“…For example, other sensor technologies that could benet from KLT denoising are nanowire temperature sensors, 22 graphene-based biosensors for immunoassay of small molecules, 23 indirect absorption spectroscopy, 24 microcantilever-based detection of protein markers, 25 microcantilever-based detection of CrO 4 , 2-8 mid-infrared spectroscopy of exhaled breath analysis, 26 surface-enhanced Raman scattering (SERS) detection of organophosphate pesticides, 27 and also sensing applications where surface heating by optical beams occur. 28 In Section 2 the analysis of the random uctuation of a micro-oscillator is discussed; KLT is introduced and applied to both ambient and photoacoustically induced responses. The random uctuation in spectroscopic measurement is discussed in Section 3, where the experimental setup and analysis of the obtained infrared (IR) absorption spectra for a set of test compounds including Poplar cross sections, a biomass with considerable molecular complexity and of great importance in biofuel research are given.…”

Section: Introductionmentioning

confidence: 99%

Karhunen–Loève treatment to remove noise and facilitate data analysis in sensing, spectroscopy and other applications

Zaharov

Farahi

Snyder

et al. 2014

Analyst

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Resolving weak spectral variations in the dynamic response of materials that are either dominated or excited by stochastic processes remains a challenge. Responses that are thermal in origin are particularly relevant examples due to the delocalized nature of heat. Despite its inherent properties in dealing with stochastic processes, the Karhunen-Loève expansion has not been fully exploited in measurement of systems that are driven solely by random forces or can exhibit large thermally driven random fluctuations. Here, we present experimental results and analysis of the archetypes (a) the resonant excitation and transient response of an atomic force microscope probe by the ambient random fluctuations and nanoscale photothermal sample response, and (b) the photothermally scattered photons in pump-probe spectroscopy. In each case, the dynamic process is represented as an infinite series with random coefficients to obtain pertinent frequency shifts and spectral peaks and demonstrate spectral enhancement for a set of compounds including the spectrally complex biomass. The considered cases find important applications in nanoscale material characterization, biosensing, and spectral identification of biological and chemical agents.

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Surface heating by optical beams and application to mid-infrared imaging

Cited by 11 publications

References 13 publications

Direct mapping of local Seebeck coefficient in 2D material nanostructures via scanning thermal gate microscopy

Direct mapping of local Seebeck coefficient in 2D material nanostructures via scanning thermal gate microscopy

Direct Mapping of Local Seebeck Coefficient in 2D Material Nanostructures via Scanning Thermal Gate Microscopy

Karhunen–Loève treatment to remove noise and facilitate data analysis in sensing, spectroscopy and other applications

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