Determination of gas-phase absorption cross-sections of FeO in a shock tube using intracavity absorption spectroscopy near 611 nm

Insights into the Mechanism of Combustion Synthesis of Iron Oxide Nanoparticles Gained by Laser Diagnostics, Mass Spectrometry, and Numerical Simulations: A Mini-Review

“…86,87 The fluorescence quantum yield can be inferred from measurements of the effective fluorescence lifetime. 86 The state-specific transition cross sections can be recalculated from state-resolved fluorescence lifetimes and dispersed fluorescence spectra 88,89 or using a controlled source of intermediate species (e.g., laser photolysis or shock-tube pyrolysis) for direct absorption measurement 90,91 (see section 3.2).…”

“…Furthermore, the immunity of ICLAS to broadband losses, such as light extinction and scattering by particles, makes its application in particle-laden environments and synthesis flames especially attractive. 64,97,107 resulting from Fe(CO) 5 oxidation by CO 2 in a shock tube 91 (panels c and d of Figure 4). ICLAS enabled extending the diagnostics toolbox beyond Fe atoms, significantly advancing our ability to unravel the chemistry preceding iron oxide particle formation and bridging the gap in the knowledge of spectroscopic data via flame and shock-tube measurements of FeO, which plays a pivotal role by impacting the flame speed and linking the interconversion of Fe and iron oxides and hydroxides in the flame reaction zone 49,68 (see Figure 7).…”

“…The calibration factors associated with light collection and detection efficiency are usually deduced from Rayleigh or Raman scattering , or using fluorescence from a well-characterized system. , The fluorescence quantum yield can be inferred from measurements of the effective fluorescence lifetime . The state-specific transition cross sections can be recalculated from state-resolved fluorescence lifetimes and dispersed fluorescence spectra , or using a controlled source of intermediate species (e.g., laser photolysis or shock-tube pyrolysis) for direct absorption measurement , (see section ).…”

“…ICLAS (sometimes abbreviated as ICAS, ILS or ICLS) is an absorption spectroscopy method ultrasensitive to narrowband losses, in which the effective absorption path length is enhanced by placing the absorbing species inside the cavity of a broadband laser. − ICLAS has matured to a useful complement and often powerful alternative to LIF in combustion diagnostics, − when absolute concentration measurements are required or where detection of the fluorescence signal is hampered by collisional quenching and pre-dissociation. Furthermore, the immunity of ICLAS to broadband losses, such as light extinction and scattering by particles, makes its application in particle-laden environments and synthesis flames especially attractive. ,, Figure shows two typical examples of ICLAS implementation to an iron oxide synthesis system: mapping the gas-phase FeO spatial profile in a steady flame (panels a and b of Figure ) and time-resolved measurement of transient FeO formation resulting from Fe­(CO) 5 oxidation by CO 2 in a shock tube (panels c and d of Figure ).…”

“…Red and blue (solid and dashed) lines correspond to kinetic simulations. This figure was adapted with permission from ref . Copyright 2020 Elsevier.…”