Fluorescence excitation and emission spectra of polycyclic aromatic hydrocarbons at flame temperatures

Coe, D.; Steinfeld, J. I.

doi:10.1016/0009-2614(80)80652-x

Cited by 47 publications

(12 citation statements)

References 16 publications

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“…2 and the EEM map shown in Fig. 3 are based on absorption and fluorescence data of room-temperature, liquidphase samples and it has been known and verified that gas-phase PAHs exhibit some broadening and peak shift of fluorescence spectra, especially at higher temperatures and pressures [20,[25][26][27][28][29][30]. However, their spectral regions at different conditions do not significantly differ relative to the wide spectral range of interest in the present study and qualitative classification and characterization of PAHs should be possible.…”

Section: Excitation-emission Matrix (Eem)supporting

confidence: 54%

Investigation of early soot formation process in a diesel spray flame via excitation—emission matrix using a multi-wavelength laser source

Aizawa

Kosaka

2008

International Journal of Engine Research

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In order to investigate the early soot formation processes in diesel combustion, spectral analysis of polycyclic aromatic hydrocarbons (PAHs) formed in the early soot formation region in a diesel spray flame was conducted via the excitation—emission matrix (EEM) technique using a multi-wavelength laser source. The experiments were conducted using an optically accessible constant volume combustion vessel under diesel-like conditions (ambient temperature, Ta = 750–1130 K and ambient pressure, Pa = 2.0–3.0 MPa) at different ambient oxygen concentrations (10–21 per cent). The PAHs formed in a diesel spray flame in the combustion vessel were excited by a coherent multi-wavelength ‘rainbow’ laser light (mainly 266, 299, 342, and 398 nm, total 20 mJ) generated by converting the fourth harmonic (266 nm, 60 mJ) of a pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser using a Raman cell frequency converter filled with hydrogen (500 kPa). The spectra of laser-induced fluorescence from the PAHs excited by the different laser wavelengths in the flame were simultaneously captured with a spectrometer and an intensified charge-coupled device (ICCD) camera as EEM images. The EEM measured in diesel spray flames at different ambient temperatures and oxygen concentrations revealed that the timing and the region for PAH growth and soot particle formation are delayed and extended downstream at lower ambient temperatures and oxygen concentrations. At an ambient temperature of 940 K and an ambient oxygen concentration of 21 per cent, a variety of PAHs are detected around the ignition timing in the central region of the diesel spray flame and the PAHs grow into larger PAHs and soot particles as the combustion process progresses. At a lower ambient temperature of 750 K or lower ambient oxygen concentrations down to 10 per cent, the fluorescence from PAHs is detected in the central region of the diesel spray flame before the ignition timing and the intensity and the spectral characteristics of the PAH fluorescence do not change for a longer period until they are finally converted to soot particles in the downstream regions in the spray flame.

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Section: Excitation-emission Matrix (Eem)supporting

confidence: 54%

Investigation of early soot formation process in a diesel spray flame via excitation—emission matrix using a multi-wavelength laser source

Aizawa

Kosaka

2008

International Journal of Engine Research

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“…12 for a fuel-rich ethylene-air premixed flat flame in which femtosecond two-beam phase matching was used to achieve single-shot images of spectra yielding temperature and relative concentrations of N 2 and O 2 in a sooting flame [284]. In situ measurements of OH [113,[285][286][287], CH [288], CH 2 O [289][290][291], and PAH [113,285,287,[291][292][293][294][295][296][297][298][299][300][301][302][303][304] distributions have been accomplished using laser-induced fluorescence (LIF) [113, 285-289, 291, 294-300, 302-304] or absorption spectroscopy [292][293][294]301]. Although characterization of the combustion environment is critically important for gaining insight into factors that influence soot evolution, a full review of available diagnostics for such supporting measurements is beyond the scope of the current review.…”

Section: Diagnostics Needsmentioning

confidence: 99%

Understanding the ignition mechanism of high-pressure spray flames

Dahms

Paczko

Skeen

et al. 2017

Proceedings of the Combustion Institute

129

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Soot is responsible for notoriously detrimental effects on human health, air quality, and global and regional climate. Controlling soot emissions to the atmosphere will require overcoming large gaps in the understanding of soot formation and physical and chemical evolution during combustion. These gaps in understanding are largely attributable to the complexity of the chemical and physical system combined with a paucity of diagnostic techniques available for probing soot non-invasively and under a wide range of combustion conditions. This review briefly summarizes the chemistry of soot formation and evolution during combustion and describes diagnostic tools that are available to make these measurements. Despite the availability and value of a host of ex situ particle diagnostic techniques, because of space limitations, this review is restricted to a discussion of in situ diagnostic methods. The review concludes with a brief discussion of needs for new diagnostic tools to probe soot chemistry.

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“…Light sources in the UV can also induce electronic transitions and subsequent emission of fluorescence in specific classes of molecules such as polycyclic aromatic hydrocarbons (PAH) and oxygen-containing compounds [36][37][38][39][40][41][42][43]. For nanoparticles, exhibiting molecular characteristics, Laser Induced Fluorescence (LIF) may also be a useful detection tool [44][45][46].…”

Section: Diagnostics For Particlesmentioning

confidence: 99%