Raman Method

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 75393 Experts worldwide ranked by ideXlab platform

Xing Zhang - One of the best experts on this subject based on the ideXlab platform.

  • A dual-wavelength flash Raman Method for simultaneously measuring thermal diffusivity and line thermal contact resistance of an individual supported nanowire
    Thermochimica Acta, 2020
    Co-Authors: Aoran Fan, Jinhui Liu, Haidong Wang, Xing Zhang
    Abstract:

    Abstract Precise thermal characterization of supported nanowires is crucial for the thermal analysis in their applications. This paper developed a one-dimension dual-wavelength flash Raman (DFR) Method to measure the thermal diffusivity and line thermal contact resistance of an individual supported nanowire. In this Method, two laser pulses with different wavelengths are used for heating the sample and probing the Raman spectra, respectively. The temperature variation curves can be captured by changing the time delay between the two pulses, and the temporal resolution can reach to 100 ps. The laser absorption coefficient of the nanowire can be eliminated in the determination of thermal properties, which greatly enhance the measurement accuracy. To the consideration of accuracy and easy operation of the measurement, for different situations, the complete model considered the temperature variation of the substrate and the simplified model ignored the substrate temperature rise were both analyzed. This Method has been used to measure a silicon nanowire which is supported by a sliver substrate. Experimental results of the supported silicon nanowire show that the thermal diffusivity of silicon nanowire is (7.3 ± 1.4) ×10−5 m2/s, and the line thermal contact resistance between the nanowire and the substrate is (2.6 ± 0.1) m·K/W.

  • Non-contact T-type Raman Method for measurement of thermophysical properties of micro-/nanowires.
    The Review of scientific instruments, 2019
    Co-Authors: Jinhui Liu, Hao Liu, Xing Zhang
    Abstract:

    A non-contact T-type Raman Method was presented for characterizing the thermophysical properties of individual micro-/nanowires, using a suspended sample-attached T-type sensor. The sensor wire’s thermal diffusivity was determined by the laser flash Raman spectroscopy Method, which directly extracts the thermal diffusivity (α) by comparing the square pulse and continuous laser heating induced temperature rise. The test wire’s thermal conductivity (λ) can be extracted by comparing the laser spot heating the sensor wire induced local temperature rise before and after the attachment of the test wire. This non-contact T-type Method was verified by comparing the measured thermal conductivity of an individual 25 µm diameter Pt wire with the standard value and then applied in the thermal transport property characterization of an individual 17 µm diameter carbon fiber. Experimental results indicated that the thermal conductivity first increases and then decreases in the temperature range from 215 K to 470 K. In principle, the presented non-contact Method is applicable to characterize any individual micro-/nanowires, even those without Raman spectra.A non-contact T-type Raman Method was presented for characterizing the thermophysical properties of individual micro-/nanowires, using a suspended sample-attached T-type sensor. The sensor wire’s thermal diffusivity was determined by the laser flash Raman spectroscopy Method, which directly extracts the thermal diffusivity (α) by comparing the square pulse and continuous laser heating induced temperature rise. The test wire’s thermal conductivity (λ) can be extracted by comparing the laser spot heating the sensor wire induced local temperature rise before and after the attachment of the test wire. This non-contact T-type Method was verified by comparing the measured thermal conductivity of an individual 25 µm diameter Pt wire with the standard value and then applied in the thermal transport property characterization of an individual 17 µm diameter carbon fiber. Experimental results indicated that the thermal conductivity first increases and then decreases in the temperature range from 215 K to 470 K. In p...

  • Frequency-domain Raman Method to measure thermal diffusivity of one-dimensional microfibers and nanowires
    International Journal of Heat and Mass Transfer, 2019
    Co-Authors: Koji Takahashi, Xing Zhang
    Abstract:

    Abstract Thermal property measurement of individual micro- and nano-materials has been very challenging and the development of measurement Methods is crucial for the experimental investigation of microscale and nanoscale heat transfer. Here we present a noncontact frequency-domain Raman Method to measure thermal diffusivity of individual 1D microfibers and nanowires without the need of knowing laser absorptivity. Cosine-wave modulated laser is used to heat the sample, while the laser-intensity-weighted spatiotemporal average temperature is simultaneously detected from the sample’s Raman band shift. Transient heat conduction models under periodic heating are established and analytically solved in the frequency domain with considerations of the Gaussian laser distribution and thermal contact resistance. By varying the laser modulation frequency as well as the laser spot size, we can eliminate the laser absorptivity by a normalization technique and extract the thermal diffusivity with high sensitivity. Typically, if the thermal diffusivity is on the order of 10−4 m2/s, we need to use the modulation frequencies on the order of 10 Hz to measure millimeter long microfibers, and ∼MHz frequencies to measure micrometer long nanowires. We also demonstrate that any kind of periodic laser modulation can be decomposed to a series of cosine modes and readily analyzed by this frequency-domain approach, which can greatly broaden the applications of transient Raman techniques.

  • characterization of thermal transport and laser absorption properties of an individual graphitized carbon fiber by applying Raman thermography
    Thermochimica Acta, 2018
    Co-Authors: Jinhui Liu, Xing Zhang
    Abstract:

    Abstract Graphitized carbon fibers have potential applications owing to their excellent electrical, mechanical, thermal and optical properties. Thermal transport and laser absorption properties are the fundamental parameters for the thermal design, but difficult for determining due to their very small characteristic sizes. In this study, we systematically investigated the temperature (T)-dependent apparent thermal conductivity (λa), thermal conductivity (λ), thermal contact resistance (Rc, between sample and heat sink) and laser absorptivity (α) of an individual graphitized carbon fiber using a non-contact Raman Method. This Method and the experimental system were verified by comparing the measured thermal conductivity of a 10.0 μm diameter platinum wire with the standard data. The measured λ of this graphitized carbon fiber decreases from 372.4 to 330.1 W/(m·K) as T increases from 338 to 496 K, indicating the three-phonon Umklapp scattering rate increases with temperature. Rc increases with T from 3.44 × 103 to 6.35 × 103 K/W in this experimental temperature range, and the laser (488 nm wavelength) absorptivity is determined to be 0.90 ± 0.02.

  • Variable-spot-size laser-flash Raman Method to measure in-plane and interfacial thermal properties of 2D van der Waals heterostructures
    International Journal of Heat and Mass Transfer, 2018
    Co-Authors: Xing Zhang, Koji Takahashi
    Abstract:

    Abstract Stacked layers of different atomically thin 2D materials is called the van der Waals (vdW) heterostructure, which has become a rapidly developing research field due to its extraordinary and tunable properties. In this paper, we develop a variable-spot-size laser-flash Raman Method to in-situ measure the thermal properties as well as the laser absorption in the supported 2D vdW heterostructure with arbitrary layers. The extracted thermal properties include the in-plane thermal conductivity and diffusivity of each layer, and interfacial thermal conductance between every two adjacent layers. A three-dimensional transient heat conduction model is developed and analytically solved to describe the process of pulsed Gaussian laser heating supported n-layer heterostructure. The temperature of each atomic layer can be simultaneously non-contact detected from their distinct Raman peaks whose positions are temperature dependent. The laser spot sizes and pulse durations are varied to generate multiple temperature curves. The multiple thermal properties as well as the laser absorption can be extracted by simultaneously fitting these temperature curves into the analytical solutions at multiple spot sizes or/and pulse durations. We also establish the approach of sensitivity and uncertainty analysis for the multi-response multi-parameter least-square fitting in our proposed measurement Methods. Case studies show that the transient temperature curves are generally more sensitive to the thermal properties than the steady-state temperatures at variable spot sizes. All the unknown thermal properties and laser absorption can be extracted with sufficiently high accuracy if multiple transient temperature curves at multiple spot sizes are simultaneously fitted into the analytical solution. The measurement Method and uncertainty analysis approach presented here are useful for investigating the thermal transport in the emerging 2D materials and vdW heterostructures.

Jinhui Liu - One of the best experts on this subject based on the ideXlab platform.

  • A dual-wavelength flash Raman Method for simultaneously measuring thermal diffusivity and line thermal contact resistance of an individual supported nanowire
    Thermochimica Acta, 2020
    Co-Authors: Aoran Fan, Jinhui Liu, Haidong Wang, Xing Zhang
    Abstract:

    Abstract Precise thermal characterization of supported nanowires is crucial for the thermal analysis in their applications. This paper developed a one-dimension dual-wavelength flash Raman (DFR) Method to measure the thermal diffusivity and line thermal contact resistance of an individual supported nanowire. In this Method, two laser pulses with different wavelengths are used for heating the sample and probing the Raman spectra, respectively. The temperature variation curves can be captured by changing the time delay between the two pulses, and the temporal resolution can reach to 100 ps. The laser absorption coefficient of the nanowire can be eliminated in the determination of thermal properties, which greatly enhance the measurement accuracy. To the consideration of accuracy and easy operation of the measurement, for different situations, the complete model considered the temperature variation of the substrate and the simplified model ignored the substrate temperature rise were both analyzed. This Method has been used to measure a silicon nanowire which is supported by a sliver substrate. Experimental results of the supported silicon nanowire show that the thermal diffusivity of silicon nanowire is (7.3 ± 1.4) ×10−5 m2/s, and the line thermal contact resistance between the nanowire and the substrate is (2.6 ± 0.1) m·K/W.

  • Non-contact T-type Raman Method for measurement of thermophysical properties of micro-/nanowires.
    The Review of scientific instruments, 2019
    Co-Authors: Jinhui Liu, Hao Liu, Xing Zhang
    Abstract:

    A non-contact T-type Raman Method was presented for characterizing the thermophysical properties of individual micro-/nanowires, using a suspended sample-attached T-type sensor. The sensor wire’s thermal diffusivity was determined by the laser flash Raman spectroscopy Method, which directly extracts the thermal diffusivity (α) by comparing the square pulse and continuous laser heating induced temperature rise. The test wire’s thermal conductivity (λ) can be extracted by comparing the laser spot heating the sensor wire induced local temperature rise before and after the attachment of the test wire. This non-contact T-type Method was verified by comparing the measured thermal conductivity of an individual 25 µm diameter Pt wire with the standard value and then applied in the thermal transport property characterization of an individual 17 µm diameter carbon fiber. Experimental results indicated that the thermal conductivity first increases and then decreases in the temperature range from 215 K to 470 K. In principle, the presented non-contact Method is applicable to characterize any individual micro-/nanowires, even those without Raman spectra.A non-contact T-type Raman Method was presented for characterizing the thermophysical properties of individual micro-/nanowires, using a suspended sample-attached T-type sensor. The sensor wire’s thermal diffusivity was determined by the laser flash Raman spectroscopy Method, which directly extracts the thermal diffusivity (α) by comparing the square pulse and continuous laser heating induced temperature rise. The test wire’s thermal conductivity (λ) can be extracted by comparing the laser spot heating the sensor wire induced local temperature rise before and after the attachment of the test wire. This non-contact T-type Method was verified by comparing the measured thermal conductivity of an individual 25 µm diameter Pt wire with the standard value and then applied in the thermal transport property characterization of an individual 17 µm diameter carbon fiber. Experimental results indicated that the thermal conductivity first increases and then decreases in the temperature range from 215 K to 470 K. In p...

  • characterization of thermal transport and laser absorption properties of an individual graphitized carbon fiber by applying Raman thermography
    Thermochimica Acta, 2018
    Co-Authors: Jinhui Liu, Xing Zhang
    Abstract:

    Abstract Graphitized carbon fibers have potential applications owing to their excellent electrical, mechanical, thermal and optical properties. Thermal transport and laser absorption properties are the fundamental parameters for the thermal design, but difficult for determining due to their very small characteristic sizes. In this study, we systematically investigated the temperature (T)-dependent apparent thermal conductivity (λa), thermal conductivity (λ), thermal contact resistance (Rc, between sample and heat sink) and laser absorptivity (α) of an individual graphitized carbon fiber using a non-contact Raman Method. This Method and the experimental system were verified by comparing the measured thermal conductivity of a 10.0 μm diameter platinum wire with the standard data. The measured λ of this graphitized carbon fiber decreases from 372.4 to 330.1 W/(m·K) as T increases from 338 to 496 K, indicating the three-phonon Umklapp scattering rate increases with temperature. Rc increases with T from 3.44 × 103 to 6.35 × 103 K/W in this experimental temperature range, and the laser (488 nm wavelength) absorptivity is determined to be 0.90 ± 0.02.

  • simultaneous measurement of thermal properties and convective heat transfer coefficient of individual carbon fiber using Raman spectroscopy
    CIESC Journal, 2014
    Co-Authors: Jinhui Liu, Haidong Wang, Xing Zhang
    Abstract:

    The new developed laser-Raman Method was used to measure the thermal conductivity of individual carbon fiber at 333.15K.The local temperature along the individual fiber was determined by Raman shift.The measuring result without concerning thermal contact resistance is 110.6W·m-1·K-1, which fits well with data from direct-current Method.Then the Method is made better.By changing laser heating spot,the thermal contact resistance is determined.And then the intrinsic thermal conductivity is determined to be 135.0 W · m-1·K-1 by concerning the thermal contact resistance.Moreover,by changing laser heating power the laser absorptivity is determined.And when the fiber is being heated in the air,the convective heat transfer coefficient is obtained by iterative solution.

T. De Beer - One of the best experts on this subject based on the ideXlab platform.

  • In-line UV spectroscopy for the quantification of low-dose active ingredients during the manufacturing of pharmaceutical semi-solid and liquid formulations
    Analytica chimica acta, 2018
    Co-Authors: N. Bostijn, Chris Vervaet, Mario Hellings, M. Van Der Veen, T. De Beer
    Abstract:

    Abstract UltraViolet (UV) spectroscopy was evaluated as an innovative Process Analytical Technology (PAT) - tool for the in-line and real-time quantitative determination of low-dosed active pharmaceutical ingredients (APIs) in a semi-solid (gel) and a liquid (suspension) pharmaceutical formulation during their batch production process. The performance of this new PAT-tool (i.e., UV spectroscopy) was compared with an already more established PAT-Method based on Raman spectroscopy. In-line UV measurements were carried out with an immersion probe while for the Raman measurements a non-contact PhAT probe was used. For both studied formulations, an in-line API quantification model was developed and validated per spectroscopic technique. The known API concentrations (Y) were correlated with the corresponding in-line collected preprocessed spectra (X) through a Partial Least Squares (PLS) regression. Each developed quantification Method was validated by calculating the accuracy profile on the basis of the validation experiments. Furthermore, the measurement uncertainty was determined based on the data generated for the determination of the accuracy profiles. From the accuracy profile of the UV- and Raman-based quantification Method for the gel, it was concluded that at the target API concentration of 2% (w/w), 95 out of 100 future routine measurements given by the Raman Method will not deviate more than 10% (relative error) from the true API concentration, whereas for the UV Method the acceptance limits of 10% were exceeded. For the liquid formulation, the Raman Method was not able to quantify the API in the low-dosed suspension (0.09% (w/w) API). In contrast, the in-line UV Method was able to adequately quantify the API in the suspension. This study demonstrated that UV spectroscopy can be adopted as a novel in-line PAT-technique for low-dose quantification purposes in pharmaceutical processes. Important is that none of the two spectroscopic techniques was superior to the other for both formulations: the Raman Method was more accurate in quantifying the API in the gel (2% (w/w) API), while the UV Method performed better for API quantification in the suspension (0.09% (w/w) API).

  • Raman spectroscopic Method for the determination of medroxyprogesterone acetate in a pharmaceutical suspension: validation of quantifying abilities, uncertainty assessment and comparison with the high performance liquid chromatography reference metho
    Analytica chimica acta, 2007
    Co-Authors: T. De Beer, Willy R. G. Baeyens, A. Vermeire, D. Broes, J.p. Remon, Chris Vervaet
    Abstract:

    Abstract An alternative fast and non-destructive validated Raman spectroscopic analytical procedure, requiring no sample preparation, was compared with the industrially applied HPLC reference Method (Pfizer Manufacturing Belgium) for the quantitative determination of medroxyprogesterone acetate (MPA) in DepoProvera® suspensions (150 mg mL−1, Pfizer). The Raman calibration model was developed by plotting the peak intensity of the baseline-corrected and normalized spectral band (corrected by external standard measurements) between 1595 and 1620 cm−1 against known MPA concentrations in standards. At this band, no spectral interferences from the suspension medium are observed. The most suitable model for the calibration data (straight line or higher order polynomial) was determined by evaluating the fit and predictive properties of the models. In a second step, the developed Raman spectroscopic analytical Method was validated by calculating the accuracy profile on the basis of the analysis results of validation samples. Furthermore, based on the data of the accuracy profile, the measurement uncertainty was determined. Finally, as the aim of the alternative Method is to replace the destructive, time-consuming HPLC Method, requiring sample preparation, it needs to be demonstrated that the new Raman Method performs at least as good as the HPLC Method. Therefore, the performance (precision and bias) of both Methods was compared. A second order polynomial calibration curve through the calibration data supplies the best predictive properties and gives an acceptable fit. From the accuracy profile, it was concluded that at the target concentration (150 mg mL−1), 95 out 100 future routine measurements will be included within the acceptance limits (5%). Comparison of the alternative Method with the reference Method at the target concentration indicates that the Raman Method performs at least as good as the HPLC Method for precision (repeatability and intermediate precision) and bias. The fast and non-destructive Raman Method hence provides an alternative for the destructive and time-consuming HPLC procedure.

  • Influence of particle size on the quantitative determination of salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy
    European Journal of Pharmaceutical Sciences, 2006
    Co-Authors: T. De Beer, Willy R. G. Baeyens, Chris Vervaet, Y. Vander Heyden, Jean Paul Remon, Francis Verpoort
    Abstract:

    A second order polynomial calibration model was developed and statistically validated for the direct and non-destructive quantitative analysis - without sample preparation - of the active pharmaceutical ingredient (API) salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy. The calibration curve was modeled by plotting the peak intensity of the vector normalized spectral band between 757 and 784cm(-1) against the known salicylic acid concentrations in standards. At this band, no spectral interferences from the ointment vehiculum (white vaseline) are observed. For the validation of the polynomial model, its fit and its predictive properties were evaluated. The validated model was used for the quantification of 25 ointments, compounded by different retail pharmacists. The same standards and samples were used, both for development and validation of a regression model and for quantitative determination by HPLC - with sample preparation - as described for the related substances of salicylic acid in the Ph. Eur. IV. The quantification results obtained by the FT-Raman Method corresponded with the HPLC results (p=0.22), provided that the particle size of salicylic acid in the standards is the same as in the analyzed samples. The non-destructive FT-Raman Method is a reliable alternative for the destructive HPLC Method, as it is faster and does not require sample pre-treatment procedures.

  • Development and validation of a direct, non-destructive quantitative Method for medroxyprogesterone acetate in a pharmaceutical suspension using FT-Raman spectroscopy
    European Journal of Pharmaceutical Sciences, 2004
    Co-Authors: T. De Beer, Willy R. G. Baeyens, J.p. Remon, Chris Vervaet, Geert Vergote, Francis Verpoort
    Abstract:

    A simple linear regression Method was developed and statistically validated for the direct and non-destructive quantitative analysis--without sample preparation--of the active pharmaceutical ingredient (API) medroxyprogesterone acetate (MPA) in an aqueous pharmaceutical suspension (150 mg in 1.0 ml) using FT-Raman spectroscopy. The linear regression was modelled by plotting the highest peak intensity of the vector normalized spectral band between 1630 and 1590 cm-1 against different MPA standard suspension concentrations. At this band, no spectral interferences from additives in the suspension are observed. The validated model was used for the quantification of a commercial suspension (150 mg in 1.0 ml) of the commercialized preparations. The same standards and samples were used, respectively, for the development and validation of a simple linear regression model and for the quantitative determination by means of HPLC-with sample preparation-as described for the related substances of MPA in the Ph. Eur. IV. The quantification results obtained by the FT-Raman Method corresponded with the claimed label concentration (150.01+/-0.96 mg/ml (n=6)). Applying the HPLC Method, however, a systematic error was observed (157.77+/-0.94 mg/ml (n=6)). The direct FT-Raman Method hence appears the most reliable for the quantification of the MPA component in suspension, compared to the HPLC Method that requires sample preparation. The latter Method provides a systematic error because the exact volume or density of a suspension sample is unknown. A precise isolation of fixed volumes from a suspension is rather unfeasible because of the continuous sagging of the suspended particles and their sticking to the used materials in the isolation process.

Douglas Both - One of the best experts on this subject based on the ideXlab platform.

  • Development and Robustness Verification of an At-Line Transmission Raman Method for Pharmaceutical Tablets Using Quality by Design (QbD) Principles
    Journal of Pharmaceutical Innovation, 2018
    Co-Authors: Claudia C. Corredor, Conny Vikstrom, Anna Persson, Xin Bu, Douglas Both
    Abstract:

    PurposeThe purpose of the present study was to investigate the feasibility of developing a fast non-destructive at-line transmission Raman spectroscopy (TRS) Method for core tablet potency and content uniformity (CU) as part of a real-time release testing (RTRt) control strategy.MethodsThe effects of tablet hardness and weight (thickness), API particle size, and concentration were studied by using a novel experimental design called generalized subset designs (GSDs). A subset of 28 experiments plus three replicate center points were selected for a total of 31 experiments. Matrix effects included tablets with active pharmaceutical ingredient (API) at seven concentration levels (14 to 26% w / w ), and API particle size (17 to 71 μm), tablet weight (275 to 328 mg), and tablet hardness (8 to 16 SCU) at two levels.ResultsThree calibration models were developed, by using partial least squares (PLS) and different preprocessing conditions (model nos. 1 to 3). In model no. 1, all matrix effects were excluded. This model showed high potency prediction errors (RMSEP of 10.0%). When all matrix variations were included in the multivariate calibration according to the GSD as shown in model nos. 2 and 3, the prediction accuracy was greatly improved (RMSEP 2.56 and 1.74% respectively). The statistical significance of the tablet weight, hardness, and API particle size in the %Recovery (TRS vs. the reference HPLC Method) was investigated by using MODDE Pro (Sartorius Stedim Data Analytics). Statistically significant effects were identified if the calculated p value was ≤ 0.05. The main effect hardness, the cross-term hardness×particle size, and the quadratic term cal level×cal level showed to be statistically significant. However, these effects had a very small impact on tablet prediction accuracy (± 1.0% w / w ) well within the intermediate precision of the Method.ConclusionA non-destructive TRS Method for core tablet potency and CU was fully validated, following ICH Q2 and EMEA NIR guidelines. The applicability of the Method to process development batches was demonstrated and compared to a previously developed and validated NIR Method.

  • Development and Robustness Verification of an At-Line Transmission Raman Method for Pharmaceutical Tablets Using Quality by Design (QbD) Principles
    Journal of Pharmaceutical Innovation, 2018
    Co-Authors: Claudia C. Corredor, Conny Vikstrom, Anna Persson, Douglas Both
    Abstract:

    The purpose of the present study was to investigate the feasibility of developing a fast non-destructive at-line transmission Raman spectroscopy (TRS) Method for core tablet potency and content uniformity (CU) as part of a real-time release testing (RTRt) control strategy. The effects of tablet hardness and weight (thickness), API particle size, and concentration were studied by using a novel experimental design called generalized subset designs (GSDs). A subset of 28 experiments plus three replicate center points were selected for a total of 31 experiments. Matrix effects included tablets with active pharmaceutical ingredient (API) at seven concentration levels (14 to 26%w/w), and API particle size (17 to 71 μm), tablet weight (275 to 328 mg), and tablet hardness (8 to 16 SCU) at two levels. Three calibration models were developed, by using partial least squares (PLS) and different preprocessing conditions (model nos. 1 to 3). In model no. 1, all matrix effects were excluded. This model showed high potency prediction errors (RMSEP of 10.0%). When all matrix variations were included in the multivariate calibration according to the GSD as shown in model nos. 2 and 3, the prediction accuracy was greatly improved (RMSEP 2.56 and 1.74% respectively). The statistical significance of the tablet weight, hardness, and API particle size in the %Recovery (TRS vs. the reference HPLC Method) was investigated by using MODDE Pro (Sartorius Stedim Data Analytics). Statistically significant effects were identified if the calculated p value was ≤ 0.05. The main effect hardness, the cross-term hardness×particle size, and the quadratic term cal level×cal level showed to be statistically significant. However, these effects had a very small impact on tablet prediction accuracy (± 1.0%w/w) well within the intermediate precision of the Method. A non-destructive TRS Method for core tablet potency and CU was fully validated, following ICH Q2 and EMEA NIR guidelines. The applicability of the Method to process development batches was demonstrated and compared to a previously developed and validated NIR Method.

Aoran Fan - One of the best experts on this subject based on the ideXlab platform.

  • A dual-wavelength flash Raman Method for simultaneously measuring thermal diffusivity and line thermal contact resistance of an individual supported nanowire
    Thermochimica Acta, 2020
    Co-Authors: Aoran Fan, Jinhui Liu, Haidong Wang, Xing Zhang
    Abstract:

    Abstract Precise thermal characterization of supported nanowires is crucial for the thermal analysis in their applications. This paper developed a one-dimension dual-wavelength flash Raman (DFR) Method to measure the thermal diffusivity and line thermal contact resistance of an individual supported nanowire. In this Method, two laser pulses with different wavelengths are used for heating the sample and probing the Raman spectra, respectively. The temperature variation curves can be captured by changing the time delay between the two pulses, and the temporal resolution can reach to 100 ps. The laser absorption coefficient of the nanowire can be eliminated in the determination of thermal properties, which greatly enhance the measurement accuracy. To the consideration of accuracy and easy operation of the measurement, for different situations, the complete model considered the temperature variation of the substrate and the simplified model ignored the substrate temperature rise were both analyzed. This Method has been used to measure a silicon nanowire which is supported by a sliver substrate. Experimental results of the supported silicon nanowire show that the thermal diffusivity of silicon nanowire is (7.3 ± 1.4) ×10−5 m2/s, and the line thermal contact resistance between the nanowire and the substrate is (2.6 ± 0.1) m·K/W.