Laser Flash Raman Spectroscopy Method for Characterizing the Specific Heat of a Single Nanoparticle

2019 ◽  
Vol 19 (11) ◽  
pp. 7004-7013 ◽  
Author(s):  
Aoran Fan ◽  
Qinyi Li ◽  
Weigang Ma ◽  
Xing Zhang
Keyword(s):  
Raman Spectroscopy ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Laser Flash ◽  
Measurement Methods ◽  
Lumped Parameter Model ◽  
Spectroscopy Method ◽  
Thermal Contact Conductance ◽  
Single Nanoparticle ◽  
Suspended Substrate

Nanoparticles are widely used in composite materials, nanoscale devices, biological detectors and medical treatment. The thermophysical properties of a single nanoparticle are, therefore, important for both nanotechnology and nanoscience applications. However, property measurements are limited by the spatial resolution of conventional measurement methods, so there are not yet any effective measurement methods to characterize the thermophysical properties of a single nanoparticle. This paper describes a laser flash Raman spectroscopy method for measuring the specific heat of a single nanoparticle supported on a free-standing substrate based on a lumped parameter model for the nanoparticle coupled with a transient 2D thermal conduction model for the suspended substrate. A series of square laser pulses are assumed to be used to heat the supported single nanoparticle in a vacuum. The temperature increases in the single nanoparticle and the suspended substrate are then measured based on their Raman band shifts. The laser absorption coefficients of the nanoparticle and the substrate are then eliminated by comparing the temperature increases measured using different laser pulse widths. The specific heat of the nanoparticle and the thermal contact conductance between the nanoparticle and the substrate can then be extracted by fitting the temperatures of both the nanoparticle and the substrate. Case studies show that the method can accurately measure the specific heat of a single nanoparticle about 100 nm in diameter using ~1 ns pulse widths. The influence of the nanoparticle geometry and the thermophysical properties of the substrate are also discussed.

Laser Flash Raman Spectroscopy Method for Characterizing Thermal Diffusivity of Suspended and Supported 2D Nanomaterials

2016 ◽  
Author(s):  
Qin-Yi Li ◽  
Xing Zhang
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Thermal Diffusivity ◽  
Laser Power ◽  
2D Materials ◽  
Laser Flash ◽  
Spectroscopy Method ◽  
Measured Temperature ◽  
Laser Absorption ◽  
2D Nanomaterials

2D nanomaterials have been attracting extensive research interests due to their superior properties and the accurate thermophysical characterization of 2D materials is very important for nanoscience and nanotechnology. Recently, a noncontact technique based on the temperature dependent Raman band shifts has been used to measure the thermal conductivity of 2D materials. However, the heat flux, i.e. the absorbed laser power, was either theoretically estimated or measured by a laser power meter with uncertainty, resulting in large errors in thermal conductivity determination. This paper presents a transient “laser flash Raman spectroscopy” method for measuring the thermal diffusivity of 2D nanomaterials in both the suspended and supported forms without knowing laser absorption. Square pulsed laser instead of continuous laser is used to heat the sample and the laser absorption can be eliminated by comparing the measured temperature rises for different laser heating time and laser spot radii. This method is sensitive for characterizing typical 2D materials and useful for nanoscale heat transfer research.

Laser flash-Raman spectroscopy method for the measurement of the thermal properties of micro/nano wires

2015 ◽  
Vol 86 (1) ◽  
pp. 014901 ◽  
Author(s):  
Jinhui Liu ◽  
Haidong Wang ◽  
Yudong Hu ◽  
Weigang Ma ◽  
Xing Zhang
Keyword(s):  
Raman Spectroscopy ◽  
Thermal Properties ◽  
Laser Flash ◽  
Spectroscopy Method ◽  
Nano Wires

Thermal Properties Measurement of Particulate Fouling Samples of Air-Cooled Heat Exchangers Using Laser Flash Method

2020 ◽  
Author(s):  
Arjun Sharma ◽  
M. D. Islam ◽  
Ebrahim Al Hajri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Middle East ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Heat Exchangers ◽  
Laser Flash ◽  
Flash Method ◽  
Particulate Fouling ◽  
Major Factors

Abstract Fouling is one of the major factors that drastically affects heat exchanger performance. Especially in Middle East where most of the heat exchangers are air cooled due to scarcity of water. As these heat exchangers are placed in a harsh climate, they are at high risk of low performance due to dusty/sticky particulate fouling. In order to identify possible active/passive methods to control or ideally eliminate particulate fouling, it is desirable to know exact thermophysical properties of such particulate fouling. This study presents thermophysical property characterization of selected fouling samples from eight different fin fan heat exchangers installed in an oil & gas facility in the Middle East. Laser flash Analysis (LFA) method is a well-known technique for measurement of the thermophysical properties: thermal diffusivity, specific heat and thermal conductivity of materials. A new technique was developed to prepare powder particulate fouling samples to make them as disc shaped samples while maintaining the range of ± 12 mm diameter and ± 2 mm thickness. The LFA measurements was conducted using LFA 447 Nano Flash Netzsch over the temperature range from 25 °C to 125°C. The thermal diffusivity was measured with an accuracy of ± 3% and the specific heat capacity with an accuracy of ± 5%. As the thermal conductivity is a product of these two measured values, is calculated with an accuracy of ± 5.8% and the measurement repeatability was within 2%.

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