Multivariate Characterization of a Continuous Soot Monitoring System Based on Raman Spectroscopy

Gräfen, Markus; Nalpantidis, Konstantinos; Platte, Frank; Monz, Christian; Ostendorf, Andreas

doi:10.1080/02786826.2015.1089352

Cited by 10 publications

(8 citation statements)

References 32 publications

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“…The roughness of the titanium disks and their oxide layer generate a Raman spectrum background, which was used as a baseline in order to eliminate the spectra slopes (Calabrese et al, 2017). By using a long wavelength laser (Grafen et al, 2015) and the titanium substrates Raman signal as baseline subtraction, most of the samples do not show any residual fluorescence. Otherwise, the residual fluorescence was subtracted using a straight line.…”

Section: Sample Analysismentioning

confidence: 99%

Morphology and Raman spectra of aerodynamically classified soot samples

Baldelli

Rogak

2019

Atmos. Meas. Tech.

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Abstract. Airborne soot is emitted from combustion processes as aggregates of primary particles. The size of the primary particles and the overall aggregate size control soot transport properties, and prior research shows that these parameters may be related to the soot nanostructure. In this work, a laminar, inverted nonpremixed burner has been used as a source of soot that is almost completely elemental carbon. The inverted burner was connected to an electrical low-pressure impactor, which collected particles on stages according to the aerodynamic diameter, from 0.03 to 10 µm. The morphology was analyzed using a transmission electron microscope followed by image processing to extract projected area and average primary particle size for each aggregate (approximately 1000 aggregates analyzed in total for the nine impactor stages). Carbon nanostructure was analyzed using a Raman spectrometer, and five vibrational bands (D4, D1, D3, G, and D2) were fitted to the spectra to obtain an estimate of the carbon disorder. The average primary particle diameter increases from 15 to 30 nm as the impactor stage aerodynamic diameter increases. The D1, D3, D2, and D4 bands decreased (relative to the G band) with the particle size, suggesting that the larger aggregates have larger graphitic domains.

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Section: Sample Analysismentioning

confidence: 99%

Morphology and Raman spectra of aerodynamically classified soot samples

Baldelli

Rogak

2019

Atmos. Meas. Tech.

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“…Moreover, free-stream analysis of suspended particles (in air/gas) requires larger lasers with orders of magnitude higher power density and carefully designed optics to obtain a small focused spot to induce Raman scattering, making this approach unsuitable for field-portable instrumentation. Some recent studies have reported field-portable instruments that involve Raman analysis of collected particles on a substrate that have improved detection limits. − Our method provides superior time resolution and detection limits, and it is field-portable. While this study did not focus on fabrication of an actual field-portable prototype, all of the key components, including the CAM cell, electrical and mechanical components, pump, and the spetroscopy system, were designed for inclusion in a compact, battery-operated, hand-portable instrument.…”

Section: Resultsmentioning

confidence: 99%

Real-Time Measurement of Airborne Carbon Nanotubes in Workplace Atmospheres

Zheng

Kulkarni

2019

Anal. Chem.

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With growing applications of carbon nanomaterials, there is a concern over health risks presented by inhalation of carbon nanotube (CNT) aerosol in workplace atmospheres. Current methods used for CNT aerosol measurement lack selectivity to specific form of carbonaceous component or allotrope of interest. Moreover, the detection limits of these methods are also inadequate for short-term monitoring. Here, we describe, for the first time, a near real-time, field-portable instrument for selective quantification of airborne CNT concentration. The approach uses an automated cyclical scheme involving collect-analyze-ablate steps to obtain continuous near real-time measurement using Raman spectroscopy. The method achieves significantly lower detection limits by employing corona-assisted particle microconcentration for efficient coupling with laser Raman spectroscopy. A combination of techniques involving (i) use of characteristic Raman peaks, (ii) distinct ratio of disordered and graphitic peaks, and (iii) principal component classification and regression is employed to identify and quantify the specific form of the aerosolized carbonaceous nanomaterial. We show that the approach is capable of selectively quantifying trace single-walled CNT in the presence of interfering agents such as diesel particulate matter. The detection limit of the method for the single-walled CNT studied in this work was 60 ng m–3, corresponding to a 10 min aerosol collection period, which is significantly lower than that for the NIOSH Method 5040 (∼0.15 μg m–3 for an 8-h collection on a 25 mm filter at 4 L min–1), a commonly used method for elemental carbon. We demonstrate the automated real-time capability of this field-portable method by continuously measuring a transient single-walled CNT aerosol.

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“…This result is expected given each spectrum shares the same major characteristics and mean centering was not performed on the data; thus, PC1 is characterized by the overall shape of the spectra. Similarly, Grafen et al [ 3 ] used PCA to analyze the Raman spectra of soot derived from diesel engines and found that PC1 captured ~99.5% of the variance. Figure 6 displays the scores plot of PC3 versus PC2 for the 405 and 514 nm data.…”

Section: Resultsmentioning

confidence: 99%

“…Many studies have shown that soot generated from a wide variety of materials contain similar properties and Raman spectroscopy is commonly employed to investigate carbon allotropes and the properties of soot after combustion. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Raman spectroscopy can yield molecular structure information based on the full-width half-maximum (FWHM) and the intensity of the four defect and graphite bands. Several literature sources propose the graphite (G) [12,17] and defect bands (D1, [12,17] D2, [17] D3, [18,19] and D4 [2,7,19] ) are located at approximately 1,580, 1,350, 1,620, 1,500, and at 1,200 cm À1 , respectively.…”

Section: Introductionmentioning

confidence: 99%

Raman signatures of detonation soot

Villa‐Aleman

Darvin

Nielsen

et al. 2022

J Raman Spectroscopy

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Soot generated from the detonation of nine explosives was investigated with Raman microspectroscopy and high-resolution transmission electron microscopy (HRTEM). The first order bands, located at approximately 1,580 (G), 1,350 (D1), 1,620 cm À1 (D2), 1,500 (D3), and 1,200 (D4), are used to provide information on the carbon allotropes and defects. The intensity ratios and the full-width at half-maximum provide an indication of the disorder in the material. The Raman spectra of soot acquired from the detonation of nine explosives showed differences which can be used to identify the precursor explosive. Most differences in the spectra were correlated with the presence of amorphous carbon in the soot. In additional to identification of distinct bands in the spectra via deconvolution, principal component analysis was also used to differentiate the different types of soot. HRTEM performed on soot samples with different explosive precursors identified several distinct allotropes of carbon such as nanodiamonds, carbon onions, graphite fibers, and amorphous carbon.

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Multivariate Characterization of a Continuous Soot Monitoring System Based on Raman Spectroscopy

Cited by 10 publications

References 32 publications

Morphology and Raman spectra of aerodynamically classified soot samples

Morphology and Raman spectra of aerodynamically classified soot samples

Real-Time Measurement of Airborne Carbon Nanotubes in Workplace Atmospheres

Raman signatures of detonation soot

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