First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles

Ouf, F. X.; Parent, P.; Laffon, C.; Marhaba, I.; Ferry, Daniel; Marcillaud, B.; Antonsson, E.; Benkoula, S.; Liu, X.J.; Nicolas, Christophe; Robert, E.; Patanen, Minna; Barreda, Flory-Anne; Sublemontier, O.; Coppalle, A.; Yon, Jérôme; Miserque, F.; Mostefaoui, Toufik A.; Regier, Tom; Mitchell, James B.; Miron, Catalin

doi:10.1038/srep36495

Cited by 36 publications

(50 citation statements)

References 85 publications

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“…The image charge effect alone cannot explain the curvature Ionization energy has been reported for 2-4-nm CNPs by in situ laser ionization (26). The work function values are also available for several soot samples produced in propane diffusion flames with primary particle diameters from 27 to 36 nm (27). Among them, only one of the samples, referred to by the authors as CAST1, resembles our CNPs in morphology and composition.…”

mentioning

confidence: 80%

“…Literature data: the lower limit of the photoionization energy of CNPs by in situ laser absorption in a burner-stabilized ethylene-air flame (BS4)(26) and the work function of CAST1 soot from a propane diffusion flame(27). For CAST soot, the median diameter of the volume distribution was obtained from modeling the size distribution as a lognormal distribution with the median mobility diameter of the number distribution reported in ref 27. and the geometric SD estimated from SI Appendix, Eq.…”

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confidence: 99%

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Flame-formed carbon nanoparticles exhibit quantum dot behaviors

Liu

Singh

Saggese

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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We examine the quantum confinement in the photoemission ionization energy in air and optical band gap of carbon nanoparticles (CNPs). Premixed, stretched-stabilized ethylene flames are used to generate the CNPs reproducibly over the range of 4-23 nm in volume median diameter. The results reveal that flameformed CNPs behave like an indirect band gap material, and that the existence of the optical band gap is attributed to the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap in the polycyclic aromatic hydrocarbons comprising the CNPs. Both the ionization energy and optical band gap are found to follow closely the quantum confinement effect. The optical band gaps, measured both in situ and ex situ on the CNPs prepared in several additional flames, are consistent with the theory and the baseline data of CNPs from stretched-stabilized ethylene flames, thus indicating the observed effect to be general and that the particle size is the single most important factor governing the variation of the band gap of the CNPs studied. Cyclic voltammetry measurements and density functional theory calculations provide additional support for the quantum dot behavior observed. carbon nanoparticles | quantum dots | flames N anosized carbon grains composed of disordered polycyclic aromatic hydrocarbons (PAHs) are one of the most abundant forms of carbon material in nature (1). As a less-celebrated allotrope of carbon in comparison with fullerenes, nanotubes, and graphene, carbon nanoparticle (CNP) has its share of importance in a wide range of physical phenomena. Studies of interstellar emission spectra suggest that PAH dust grains or CNPs are ubiquitous in the interstellar media (2-5); and they are considered as the tracer of the star formation process (3, 6). CNPs are formed in flames during incomplete combustion. They are part of the soot-formation process. Mature soot or atmospheric black carbon particles often contain both elemental and organic carbon, the relative amounts of which vary by source (7). Soot impacts the global and region climate systems (8, 9) because of its light-absorbing properties (10, 11) and also as cloud condensation nuclei (12). CNPs 10-20 nm in size or fine carbon particles are themselves abundant in diesel exhausts (13). Their light-absorption properties and impact on climate forcing remain poorly characterized (14). As a material, however, CNPs have found their applications in photovoltaic and electrochemical devices, including perovskite solar cells in which flame CNPs act as a hole transfer medium (15).In contrast to the notion that soot, young or mature with respect to its growth in flames, is a broadband light absorber, recent studies have shown that CNPs several nanometers in size have well-defined optical band gaps or band edges (16)(17)(18). The band gap arises from the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the constituent PAHs (18,19). While previous studies (16-18) explored the vari...

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mentioning

confidence: 80%

mentioning

confidence: 99%

Flame-formed carbon nanoparticles exhibit quantum dot behaviors

Liu

Singh

Saggese

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…However, the SP3 regime has high peak intensities for C 14 H + 10 (m/z 178), C 16 H + 10 (m/z 202), C 18 H + 12 (m/z 228), and C 20 H + 12 (m/z 252), while the relative contributions of heavier PAHs remain comparable. Literature data converge towards the fact that the SP3 set point is distinct from the others in that (i) the organic-to-total carbon ratio is higher (87 % versus ≤ 47 % for the other set points), and (ii) the crystallites of the particles produced in these conditions are significantly smaller and form a distinct disordered arrangement exhibiting many carbon edges (Bescond et al, 2016;Marhaba et al, 2019;Ouf et al, 2016;Yon et al, 2015). Such smaller crystallites suggest that SP3 may undergo nucleation and growth processes different from those of the other set points, subsequently leading to distinct chemical compositions (e.g., different isomeric distributions) of the PM.…”

Section: Multivariate Data Analysis: Principal Component Analysis (Pca)mentioning

confidence: 86%

“…Briefly, the miniCAST contains a propane-nitrogen flame with operating conditions controlled by the flow rates of propane, nitrogen, oxidation air (Q air ), and dilution air. The working points used in this study (and others in this series; Bescond et al, 2014;Ouf et al, 2016;Yon et al, 2015) are detailed in Fig. 1.…”

Section: Sample Collectionmentioning

confidence: 99%

“…8. C − n fragments are commonly con-sidered to be markers of the EC content Pagels et al, 2013;Popovicheva et al, 2017). For instance, Pagels et al (2013) used the sum of C − n (n = 2-4) fragment signals as a marker of EC in aerosol time-of-flight mass spectrometer (ATOFMS) measurements for wood stove PM emissions, and the same marker ions have been used to discriminate diesel from biodiesel PM emissions by Popovicheva et al (2017).…”

Section: Mass Spectra Obtained By Simsmentioning

confidence: 99%

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Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

et al. 2020

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Abstract. Combustion of hydrocarbons produces both particulate- and gas-phase emissions responsible for major impacts on atmospheric chemistry and human health. Ascertaining the impact of these emissions, especially on human health, is not straightforward because of our relatively poor knowledge of how chemical compounds are partitioned between the particle and gas phases. Accordingly, we propose coupling a two-filter sampling method with a multi-technique analytical approach to fully characterize the particulate- and gas-phase compositions of combustion by-products. The two-filter sampling method is designed to retain particulate matter (elemental carbon possibly covered in a surface layer of adsorbed molecules) on a first quartz fiber filter while letting the gas phase pass through and then trap the most volatile components on a second black-carbon-covered filter. All samples thus collected are subsequently subjected to a multi-technique analytical protocol involving two-step laser mass spectrometry (L2MS), secondary ion mass spectrometry (SIMS), and micro-Raman spectroscopy. Using the combination of this two-filter sampling–multi-technique approach in conjunction with advanced statistical methods, we are able to unravel distinct surface chemical compositions of aerosols generated with different set points of a miniCAST burner. Specifically, we successfully discriminate samples by their volatile, semi-volatile, and non-volatile polycyclic aromatic hydrocarbon (PAH) contents and reveal how subtle changes in combustion parameters affect particle surface chemistry.

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In situ observation of synthesized nanoparticles in ultra-dilute aerosols via X-ray scattering

et al. 2018

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In-air epitaxy of nanostructures (Aerotaxy) has recently emerged as a viable route for fast, large-scale production. In this study, we use small-angle X-ray scattering to perform direct in-flight characterizations of the first step of this process, i.e., the engineered formation of Au and Pt aerosol nanoparticles by spark generation in a flow of N 2 gas. This represents a particular challenge for characterization because the particle density can be extremely low in controlled production. The particles produced are examined during production at operational pressures close to atmospheric conditions and exhibit a lognormal size distribution ranging from 5-100 nm. The Au and Pt particle production and detection are compared. We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding dominant physical properties, including the average particle diameter and sphericity, as influenced by particle sintering and the presence of aggregates. We observe highly sorted and sintered spherical Au nanoparticles at ultra-dilute concentrations (< 5 × 10 5 particles/cm 3) corresponding to a volume fraction below 3 × 10-10 , which is orders of magnitude below that of previously measured aerosols. We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis. Our study indicates that with high-intensity synchrotron beams and careful consideration of background removal, size and shape information can be obtained for extremely low particle concentrations with industrially relevant narrow size distributions.

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First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles

Cited by 36 publications

References 85 publications

Flame-formed carbon nanoparticles exhibit quantum dot behaviors

Flame-formed carbon nanoparticles exhibit quantum dot behaviors

Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

In situ observation of synthesized nanoparticles in ultra-dilute aerosols via X-ray scattering

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