Supplementary Information - Amazon Simple Storage … · Web viewFour different band combinations are used in the present study to model the Raman spectra of soot samples, (a) 6-band

Supplementary Information

Raman Spectroscopy and TEM Characterization of Solid Particulate Matter Emitted from Soot Generators and Aircraft Turbine Engines

Meghdad Saffaripour*, Li-Lin Tay, Kevin A. Thomson, Gregory J. Smallwood, Benjamin T. Brem, Lukas Durdina, Mark Johnson

* Corresponding author: (phone) 613-993-2176, (fax) 613-957-7869, (e-mail) [email protected], (address) National Research Council Canada, Building M-9, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada

List of Contents:

Section 1. Raman Spectroscopy of Soot

Figure S1. The background-subtracted Raman spectrum of highly-ordered pyrolytic graphite (HOPG) shows a single band centered at 1584 cm-1.

Section 2. Physical Origins of the Bands

Figure S2. Typical Raman spectrum of soot shows two broad and strongly-overlapping G and D peaks (panel a). A more-refined inspection shows that in fact, the fit to the spectrum is better represented by five different bands (panel b).

Section 3. Curve Fitting Procedure

Figure S3. Baseline-subtraction method.

Table S1. Band shapes and initial values for the five different band combinations used in this work.

Figure S4. Four different band combinations are used in the present study to model the Raman spectra of soot samples, (a) 6-band combination of Lorentzian G, D1, D2, D4, and D1 bands and a Gaussian D3 band, (b) 5-band combination consisting of Lorentzian G, D1, D2, and D4 bands and a Gaussian D3 band, (c) 4-band combination consisting of Lorentzian G, D1, and D4 bands and a Gaussian D3 band, (d) 3-band combination consisting of Lorentzian G, D1, and D4 bands, and (e) 2-band combination consisting of Lorentzian G and D bands. In this Figure, (L) = Lorentzian and (G) = Gaussian.

Table S2. The 2 and R2 values for the 2-band, 3-band, 4-band, and 5-band cumulative curve fits to the measured Raman spectra of some of the samples studied in the present work. Increasing the number of bands used for curve fitting results in an improved goodness of the fit.

Figure S5. A comparison between the averaged Raman spectra of soot samples. The curves in panel (a) are obtained by averaging the measured background-subtracted signals. The curves in panel (b) are the averaged fitted curves, calculated by fixing the centers and FWHMs of the five bands to values presented in Table 4.

Figure S6. A comparison between the Raman spectral parameters calculated based on a 6-band curve fit.

Figure S7. Comparisons between the averaged values of Raman spectral parameters, for the three groups of soot samples. The error bars show the uncertainties associated with the curve fitting procedure.

Figure S8. The plot of W(G) against I(D1)/I(G) does not fully differentiate between the soot samples emitted from the soot generators and the aircraft turbine engines.

Figure S9. Some of the spectral properties of fuel-rich and fuel-lean soot generator setpoints.

Figure S10. An image of typical particles emitted at setpoint FR1, magnification = 45,000 times.






Figure S16. An image of typical particles emitted at setpoint FL2, magnification = 45,000 times.








Figure S24. An image of typical particles emitted at setpoint E1-1, magnification = 45,000 times.






Figure S30. A comparison between the soot emitted from fuel-rich and fuel-lean conditions of the MiniCAST burner and from turboshaft engine 1, based on Raman spectral parameters and dp.

Table. S3. The elemental-to-total carbon ratio (EC/TC) of the soot emitted from soot generators. Samples have been collected on Quartz filters and analyzed using a thermal-optical EC-OC Aerosol Analyzer from Sunset Laboratory, following a thermal-optical transmittance protocol (ASTM D6877-13e1, 2013).

Table. S4. The EC/TC ratio of the soot emitted from turbine engines. Samples have been collected on Quartz filters and analyzed using a thermal-optical EC-OC Aerosol Analyzer from Sunset Laboratory, following a thermal-optical transmittance protocol (ASTM D6877-13e1, 2013). Only the results which have been corrected for the OC artefact are reported.

References

1. Raman Spectroscopy of Soot

Historically, Raman spectroscopy has played an important role in the study and characterization of carbon materials (Dresselhaus et al., 2010; Escribano et al., 2001; Ferrari and Robertson, 2001; Dennison et al., 1996; Lyon et al., 1998). This method has been widely used for over four decades to characterize pyrolytic graphite, carbon fibers, glassy carbon, fullerenes, carbon nanotubes, and graphene. In Raman spectroscopy, a laser beam excites the sample by inducing oscillating electric dipole moments. Some of the excited molecules end up in a vibrational state different from the original state, thereby scattering the laser light inelastically, i.e., at frequencies different from the excitation frequency. The shift in the frequency of the scattered light relative to the excitation frequency, referred to as Raman shift, results from the difference between the original and final energy states of the bonds. The frequency of the scattered light broadens and is recorded as a band whose position corresponds to a very specific bond frequency within the sample. For example, Figure S1, shows that the Raman spectrum of highly-ordered pyrolytic graphite (HOPG) consists of only one band, centered at a Raman shift frequency of 1584 cm-1, representative of highly-uniform sp2-bonded carbon atoms in planar graphite sheets.

Figure S1. The background-subtracted Raman spectrum of highly-ordered pyrolytic graphite (HOPG) shows a single band centered at 1584 cm-1.

2. Physical Origins of the Bands

Soot has a complex multi-component structure, composed of an amorphous structure in its inner core surrounded by a crystalline graphitic shell on its outer surface (Raj et al., 2010; Happold et al., 2007; Vander Wal et al., 2007; Wang, 2011). Figure S2(a) shows a typical Raman spectrum of soot which is composed of two broad and overlapping bands. An ideal crystalline graphitic structure consists of sp2-bonded carbon atoms in unreactive basal planes, giving rise to the G band (graphite band) centered at about 1591 cm-1 (Dresselhaus and Dresselhaus, 1982). However, most graphitic materials, including soot, have different types of defects in their graphitic structure (Pimenta et al., 2007). Strong defects generally occur at the edge planes of the graphitic crystallites which induce the D band (defect band) centered at ~1344 cm-1. Therefore, the ratio of the intensities of D and G bands can represent the edge-to-volume ratio of the graphite crystals. Figure S2(a) also shows that the sum of the intensities of the G and D bands captures the totality of the measured spectrum fairly well.

(a)

(b)

Figure S2. Typical Raman spectrum of soot shows two broad and strongly-overlapping G and D peaks (panel a). A more-refined inspection shows that in fact, the fit to the spectrum is better represented by five different bands (panel b).

More detailed inspections of the Raman spectra of carbonaceous material have shown that these spectra can be better represented with a fit of five different bands (Cuesta et al., 1994; Sadezky et al., 2005). Figure S2(b) shows these five bands for the Raman spectrum of a typical soot along with the sum of the intensities of these bands which closely reproduces the measured spectrum. In addition to the bands induced by ideal graphite (G band at 1591 cm-1) and crystallite edge defects (D1 band at 1343 cm-1), the structural disorder associated with the PAH layers at the boundaries of the crystallites, i.e., those that are not sandwiched between other PAH layers, activates the D2 band centered at ~1618 cm-1 (Dresselhaus and Dresselhaus, 1982; Sze et al., 2001). As a result, the ratio of the intensities of D2 and G bands can indicate the surface area-to-volume ratio of the graphitic crystals. The D3 band at ~1536 cm-1 is generally associated with the amorphous-carbon compounds present in soot, which are complex mixtures of sp2- and sp3-bonded carbon atoms with no order, and impurity ions, such as fluoride ions, Ca, and K (Cuesta et al., 1994; Sadezky et al., 2005; Jawhari et al., 1995). However, Parent et al. (Parent et al., 2016) have reported strong D3 bands in the Raman spectra of soot, although the HR-TEM images did not show any amorphous carbon in soot particles. As a result, Parent et al. (Parent et al., 2016) have attributed the observed D3 bands to the internal vibrational modes of small graphitic domains, including the asymmetric breathing of the carbon rings and the CC stretching of internal and edge carbons, rather than to amorphous carbon compounds.

The origins of the band centered at ~1190 cm-1, i.e., the D4 band, are less clear. Bacsa et al. (Bacsa et al., 1993) have found a significant number of mixed sp2-sp3 bonds between carbon atoms, i.e., bonds with an intermediate hybridization state between sp2 and sp3, in laser-deposited amorphous-carbon films. Such mixed bonds have given rise to broad features in the Raman spectrum, between ~600 cm-1 and ~1300 cm-1 (Bacsa et al., 1993). In particular, Bacsa et al. (Bacsa et al., 1993) have attributed the features in the ~1100 to ~1300 cm-1 frequency range to the vibration modes with the stretching character of both sp3-sp3 and sp2-sp3 bonds. Jager et al. (Jager et al., 1999) have shown that bent PAH layers in the graphitic crystallites result in an increased number of bonds with intermediate hybridization states between sp2 and sp3. Therefore, the features observed in (Bacsa et al., 1993) might have been partly caused by the deviation of PAH layers from a planar orientation. Another explanation for the D4 band has been proposed in (Ishida et al., 1986; Shirakawa et al., 1973; Lopez-Rios et al., 1996; Fitchen, 1982; Harada et al., 1980). By applying a surface-enhanced Raman spectroscopy method, Ishida et al. (Ishida et al., 1986) detected two bands at 1140 cm-1 and 1550 cm-1 on the outermost surface of carbon fibers, attributed to the stretching-vibration modes of single and double carbon-carbon bonds, respectively, of polyene-like structures on the surface of the carbon fibers. Shirakawa et al. (Shirakawa et al., 1973) also observed two bands, centered at 1080 cm-1 and 1474 cm-1, in the Raman spectra of polyacetylene films, and assigned them to the carbon-carbon single- and double-bond stretching vibrations, respectively. The Raman shift for polyacetylene molecules have been reported to be in a similar range by other researchers, for example, 1127 and 1429 cm-1 by Lpez-Rios et al. (Lopez-Rios et al., 1996), 1050-1150 cm-1 and 1450-1550 cm-1 by Fitchen (Fitchen, 1982), and 1100 and 1500 cm-1 by Harada et al. (Harada et al., 1980). Based on these findings, the origin of the D4 band in the Raman spectra of soot is likely to be one or both of the following: (1) carbon atoms with sp3 hybridization and intermediate sp2-sp3 hybridization states, the latter one possibly caused by curved PAH layers in graphitic crystallites, and (2) single carbon-carbon bonds in polyacetylene-like compounds.

It should be noted that Carpentier et al. (Carpentier et al., 2012) have proposed the presence of a sixth band, D1 centered at 1269 cm-1, in the Raman spectrum of carbonaceous particles. This band potentially originates from the merging of the subbands characteristic of the individual polyaromatic subunits. A 6-band curve fit has also been conducted in the present study.

3. Curve Fitting Procedure

Quantifying the five bands present in the Raman spectra of soot provides a wealth of information about soots chemical structure and enables the comparisons of different soot materials. In the present work, the Raman spectral analysis approach of Sadezky et al. (Sadezky et al., 2005) has been followed. The Fit Peaks Pro module of OriginPro 9.1.0 (OriginPro 9.1.0, 2013) is applied to obtain band specifications and a cumulative curve fit for the measured spectrum. To remove the effects of potential fluorescence and incandescence emissions on the Raman spectra, a linear baseline subtraction scheme has been used. The baseline is determined using selecting 30 anchor points, at frequencies below 777 cm-1 and above 1833 cm-1, connected by linear interpolation. Figure S3 shows the baseline subtraction method for one of the samples. A different program, Fityk 0.9.8 (Wojdyr, 2010), was used to analyze the measured spectra of a few of the setpoints to verify that the results are not affected by the choice of the curve-fitting software. For all the soot samples studied in this work, similar initial values for the centers and FWHMs (full width at half maximum) of the bands have been used. In a few cases, the band-parameter values have been bounded to facilitate convergence. Due to different line-broadening mechanisms, Lorentzian band shapes have been used for the G, D1, D2, D1, and D4 bands, and a Gaussian band shape has been selected to model the D3 band (Cuesta et al., 1994; Sadezky et al., 2005; Jawhari et al., 1995). Five different cumulative curves have been fitted to the measured Raman spectra, composed of two, three, four, five, and six bands, and compared. The band shapes and the initial values used for the five different curve fits are presented in Table S1. These initial values are chosen based on the results and suggestions in the literature. Different initial values were tested to ensure that the results are not dependent on the initial values of fitting parameters. Figure S4 compares a typical background-subtracted Raman spectrum with cumulative fitted curve obtained using these five band combinations.

Figure S3. Baseline-subtraction method.

Table S1. Band shapes and initial values for the five different band combinations used in this work.

Peak

Initial band

center (cm-1)

Initial FWHM

(cm-1)

2-band fit

3-band fit

4-band fit

5-band fit

6-band fit

D4

1177

49

Lorentzian

Lorentzian

Lorentzian

Lorentzian

D1

1269

103

Lorentzian

D1 (D)

1351

49

Lorentzian

Lorentzian

Lorentzian

Lorentzian

Lorentzian

D3

1522

57

Gaussian

Gaussian

Gaussian

G

1591

49

Lorentzian

Lorentzian

Lorentzian

Lorentzian

Lorentzian

D2

1625

49

Lorentzian

Lorentzian

The goodness of the fits is evaluated using the 2 and R2 values of the cumulative fitted curves. Table S2 shows these values for some of the soot generator and aircraft engine setpoints using the four curve-fitting approaches. The 2 values generally decrease and the R2 values increase as the number of bands used to model the measured Raman spectrum increases, showing that the best fit is obtained with the most-refined fit. This supports the findings of Sadezky et al. (Sadezky et al., 2005). Therefore, 5-band curve fitting is used for characterizing and comparing soots chemical structures in the present work.

Two different 5-band curve-fitting approaches have been used, one in which the intensity, center frequency, and FWHM of the bands are allowed to vary, and another one in which the center and FWHM of the five bands are fixed, such that the fitting parameter is only the amplitudes of the five bands. The results are presented in Section 3.1.

(a)

(b)

(c)

(d)

(e)

Figure S4. Four different band combinations are used in the present study to model the Raman spectra of soot samples, (a) 6-band combination of Lorentzian G, D1, D2, D4, and D1 bands and a Gaussian D3 band, (b) 5-band combination consisting of Lorentzian G, D1, D2, and D4 bands and a Gaussian D3 band, (c) 4-band combination consisting of Lorentzian G, D1, and D4 bands and a Gaussian D3 band, (d) 3-band combination consisting of Lorentzian G, D1, and D4 bands, and (e) 2-band combination consisting of Lorentzian G and D bands. In this Figure, (L) = Lorentzian and (G) = Gaussian.

Table S2. The 2 and R2 values for the 2-band, 3-band, 4-band, 5-band and 6-band cumulative curve fits to the measured Raman spectra of some of the samples studied in the present work. Increasing the number of bands used for curve fitting results in an improved goodness of the fit.

Sample

2-band

3-band

4-band

5-band

6-band

2

R2

2

R2

2

R2

2

R2

2

R2

FR1

749

0.9757

674

0.9771

418

0.9858

290

0.9904

277

0.9896

FR7

632

0.9822

491

0.9862

206

0.9942

161

0.9955

113

0.9968

FL1

148

0.9873

143

0.9877

48

0.9958

39

0.9967

33

0.9972

FL8

1027

0.9887

912

0.9900

737

0.9919

243

0.9973

235

0.9974

E1-2

1066

0.9870

950

0.9884

373

0.9954

319

0.9961

281

0.9966

E1-3

93

0.9827

89

0.9835

53

0.9901

51

0.9905

50

0.9907

E1-5

223

0.9776

199

0.9800

137

0.9863

134

0.9866

127

0.9873

E2-1

775

0.9905

749

0.9908

350

0.9957

255

0.9969

204

0.9975

E3-2

293

0.9838

260

0.9857

163

0.9911

161

0.9912

154

0.9915

(a)

(b)

Figure S5. A comparison between the averaged Raman spectra of soot samples. The curves in panel (a) are obtained by averaging the measured background-subtracted signals. The curves in panel (b) are the averaged fitted curves, calculated by fixing the centers and FWHMs of the five bands to values presented in Table 4.

(a)

(b)

(c)

(d)

Figure S6. A comparison between the Raman spectral parameters calculated based on a 6-band curve fit.

(a)

(b)

(c)

(d)

(e)

Figure S7. Comparisons between the averaged values of Raman spectral parameters for the three groups of soot samples. The error bars show the uncertainties associated with the curve fitting procedure.

Figure S8. Comparison of W(G) against I(D1)/I(G) does not fully differentiate between the soot samples emitted from the soot generators and the aircraft turbine engines.

(a)

(b)

(c)

(d)

Figure S9. Some of the spectral properties of fuel-rich and fuel-lean soot generator setpoints.





















(a)

(b)

(c)

(d)

Figure S30. A comparison between the soot emitted from fuel-rich and fuel-lean conditions of the MiniCAST burner and from turboshaft engine 1, based on Raman spectral parameters and dp.

Table. S3. The elemental-to-total carbon ratio (EC/TC) of the soot emitted from soot generators. Samples have been collected on Quartz filters and analyzed using a thermal-optical EC-OC Aerosol Analyzer from Sunset Laboratory, following a thermal-optical transmittance protocol (ASTM D6877-13e1, 2013).

Setpoint

FR1

FR2

FR3

FR4

FR5

FR6

FL1

FL2

FL3

FL4

FL5

FL6

FL7

FL8

Mean EC/TC

0.48

0.83

0.96

0.93

0.79

0.98

0.96

0.93

0.90

0.81

0.98

0.87

0.57

0.71

Table. S4. The EC/TC ratio of the soot emitted from turbine engines. Samples have been collected on Quartz filters and analyzed using a thermal-optical EC-OC Aerosol Analyzer from Sunset Laboratory, following a thermal-optical transmittance protocol (ASTM D6877-13e1, 2013). Only the results which have been corrected for the OC artefact are reported.

Setpoint

E1-1

E1-2

E1-3

E1-4

E1-5

E2-1

E2-2

E2-3

E3-1

E3-2

E3-3

Mean EC/TC

0.88

0.62

0.78

0.59

0.79

0.85

References

ASTM D6877-13e1, Standard Test Method for Monitoring Diesel Particulate Exhaust in the Workplace, ASTM International, 2013, DOI: 10.1520/D6877, available online at: http://www.astm.org/Standards/D6877.htm

Bacsa, W.S., Lannin, J.S., Pappas, D.L., Cuomo, J.J., Raman scattering of laser-deposited amorphous carbon, Phys. Rev. B 47 (16) (1993) 1093110934.

Dennison, J.R., Holtz, M., Swain, G., Raman Spectroscopy of Carbon Materials, Spectroscopy 11 (8) (1996) 3845.

Dresselhaus, M.S., Dresselhaus, G., Light scattering in graphite intercalation compounds, in Light scattering in solids III, M. Cardona and G. Gntherodt, Eds., Springer-Verlag, Berlin, 1982.

Dresselhaus, M.S., Jorio, A., Hofmann, M., Dresselhaus, G., Saito, R., Perspectives on Carbon Nanotubes and Graphene Raman Spectroscopy, Nano Lett. 10 (3) (2010) 751758.

Escribano, R., Sloan, J.J., Siddique, N., Sze, N., Dudev, T., Raman spectroscopy of carbon-containing particles, Vib. Spectrosc. 26 (2) (2001) 179186.

Ferrari, A.C., Robertson, J., Resonant Raman spectroscopy of disordered, amorphous, and diamondlike carbon, Phys. Rev. B 64 (2001) 075414.

Happold, J., Grotheer, H.-H., Aigner, M., Soot precursors consisting of stacked pericondensed PAHs, in Combustion generated fine carbonaceous particles, H. Bockhorn, A. DAnna, A. F. Sarofim, H. Wang, Eds., KIT Scientific Publishing, Karlsruhe, 2007.

Lyon, L.A., Keating, C.D., Fox, A.P., Baker, B.E., He, L., Nicewarner, S.R., Mulvaney, S.P., Natan, M.J., Raman Spectroscopy, Anal. Chem. 70 (12) (1998) 341R361R.

Carpentier, Y., Fraud, G., Dartois, E., Brunetto, R., Charon, E., Cao, A. T., ... & Pino, T. (2012). Nanostructuration of carbonaceous dust as seen through the positions of the 6.2 and 7.7 m AIBs. Astronomy & Astrophysics, 548, A40.

Cuesta, A., Dhamelincourt, P., Laureyns, J., Martinez-Alonso, A., Tascon, J.M.D., Raman microprobe studies on carbon materials, Carbon 32 (8) (1994) 15231532.

Fitchen, D.B., Resonance Raman results in polyacetylene, Mol. Cryst. Liq. Cryst. 83 (1) (1982) 95108.

Harada, I., Furukawa, Y., Tasumi, M., Shirakawa, H., Ikeda, S., Spectroscopic studies on doped polyacetylene and carotene, J. Chem. Phys. 73 (1980) 47464757.

Ishida, H., Fukuda, H., Katagiri, G., Ishitani, A., An application of surface-enhanced Raman scattering to the surface characterization of carbon materials, Appl. Spectrosc. 40 (3) (1986) 322330.

Jager, C., Henning, Th., Schlogl, R., Spillecke, O., Spectral properties of carbon black, J. Non-Cryst. Solids 258 (1999) 161179.

Jawhari, T., Roid, A., Casado, J., Raman spectroscopic characterization of some commercially available carbon black materials, Carbon 33 (11) (1995) 15611565.

Lopez-Rios, T., Sandre, E., Leclercq, S., Sauvain, E., Polyacetylene in Diamond Films Evidenced by Surface Enhanced Raman Scattering, Phys. Rev. Lett. 76 (26) (1996) 49354938.

OriginPro 9.1.0, Version 9.1.0 (64-bit) Sr2, OriginLab Corporation, USA, released in 2013, http://www.originlab.com

Pimenta, M.A., Dresselhaus, G., Dresselhaus, M.S., Cancado, L.G., Jorio, A., Saito, R., Studying disorder in graphite-based systems by Raman spectroscopy, Phys. Chem. Chem. Phys. 9 (2007) 12761291.

Raj, A., Sander, M., Janardhanan, V., Kraft, M., A study on the coagulation of polycyclic aromatic hydrocarbon clusters to determine their collision efficiency, Combust. Flame 157 (2010) 523534.

Sadezky, A., Muckenhuber, H., Grothe, H., Niessner, R., Pschl, U., Raman microspectroscopy of soot and related carbonaceous materials: spectral analysis and structural information, Carbon 43 (2005) 17311742.

Shirakawa, H., Ito, T., Ikeda, S., Raman Scattering and Electronic Spectra of Poly(acetylene), Polym. J. 4 (1973) 460462.

Sze, S.-K., Siddique, N., Sloan, J.J., Escribano, R., Raman spectroscopic characterization of carbonaceous aerosols, Atmos. Environ. 35 (2001) 561568.

Vander Wal, R.L., Yezerets, A., Currier, N.W., Kim, D.H., Wang, C.M., HRTEM Study of diesel soot collected from diesel particulate filters, Carbon 45 (2007) 7077.

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Wojdyr, M. (2010). Fityk: a general-purpose peak fitting program. Journal of Applied Crystallography, 43(5), 1126-1128.

1

-0.10.00.10.20.30.40.50.60.70.80.91.01.1600800100012001400160018002000Normalized Raman Intensity Raman Shift (cm

-1

)

Measured spectrumSum of bands

D bandG band


-1

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Measured spectrumSum of bands

D4 bandD1 bandG band D2 bandD3 band

0100200300400500600700800050010001500200025003000 Intensity (cnt)Raman Shift (cm -1)Raw spectrumBaselineBaseline-subtracted spectrum


-1

)

Raman spectrum6-band fitted curve

D4 (L)D1 (L)G (L)D2 (L)D3 (G)D1' (L)


-1

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-1

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-1

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D4 (L)D1 (L)G (L)


-1

)


D (L)G (L)

0.00.20.40.60.81.01.2600800100012001400160018002000Mean Normalized Raman IntensityRaman Shift (cm

-1

)

Fuel-Rich FlamesFuel-Lean FlamesEngines

0.00.20.40.60.81.01.2600800100012001400160018002000Mean Normalized Raman IntensityRaman Shift (cm-1)Fuel-Rich FlamesFuel-Lean FlamesEngines

0.00.51.01.52.02.53.00246 I(D

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)/I(G)I(D

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0.02.04.06.08.010.00246 I(D

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0.00.51.01.52.02.53.00246 I(D

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0.00.10.20.30.40.50.60.70.81I(D1)/I(total)EnginesFuel-LeanFuel-Rich

0.000.050.100.151I(D2)/I(total)EnginesFuel-LeanFuel-Rich

0.000.050.100.150.201I(D3)/I(total)EnginesFuel-LeanFuel-Rich

0.000.050.100.150.200.250.301I(D4)/I(total)EnginesFuel-LeanFuel-Rich

0.000.050.100.151I(G)/I(total)EnginesFuel-LeanFuel-Rich

20304050607080036912 W(G)I(D

1

)/I(G)Fuel-Rich FlamesFuel-Lean FlamesEnginesHOPG

012345678910FR1FR1FR2FR3FR4FR5FR6FR6FL1FL2FL2FL2FL3FL4FL5FL6FL7FL7FL8FL8 I(D

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00.511.522.53FR1FR1FR2FR3FR4FR5FR6FR6FL1FL2FL2FL2FL3FL4FL5FL6FL7FL7FL8FL8 I(D

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)/I(G)

0123456FR1FR1FR2FR3FR4FR5FR6FR6FL1FL2FL2FL2FL3FL4FL5FL6FL7FL7FL8FL8 I(D

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)/I(G)

FR1MiniCAST

FR1MiniCAST

FR2MiniCAST

FR2MiniCAST

FR6MiniCAST

FR6MiniCAST

FL2MiniCAST

FL2MiniCAST

FL3MiniCAST

FL3MiniCAST

FL7MiniCAST

FL7MiniCAST

FL8MiniCAST

FL8MiniCAST

E1-1Engine

E1-1Engine

E1-2Engine

E1-2Engine

E1-3Engine

E1-3Engine

02468101201020304050I(D1)/I(G)DpFuel-Rich FlamesFuel-Lean FlamesEngine

00.511.522.5301020304050I(D2)/I(G)DpFuel-Rich FlamesFuel-Lean FlamesEngine

00.511.522.5301020304050I(D3)/I(G)DpFuel-Rich FlamesFuel-Lean FlamesEngine

012345601020304050I(D4)/I(G)DpFuel-Rich FlamesFuel-Lean FlamesEngine

0100200300400500600700800600800100012001400160018002000Raman Intensity (cnt)Raman Shift (cm

-1

)

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Supplementary Information - Amazon Simple Storage … · Web viewFour different band combinations are used in the present study to model the Raman spectra of soot samples, (a) 6-band