Model-free calibration of Raman measurements of reactive systems: Application to monoethanolamine/water/CO2

Kinetics of formic acid decomposition in subcritical and supercritical water – a Raman spectroscopic study

“…Multiple techniques exist to extract molecular concentrations from Raman spectra -including measuring peak heights, peak areas, and direct or indirect spectral hard modeling [22][23][24]. The Raman signal intensity from a given molecule is linearly dependent on the molar concentration of the constituent in the optical control volume, although temperature, pressure, reactions, and molecular interactions can cause non-linear spectral behavior.…”

“…For the spectra collected in this study, indirect hard modeling (IHM) is used to extract species concentration data. Calibration is accomplished using a technique detailed in [22] where a least-square optimization of stoichiometric atom balances for collected spectra allows for calibration without an extensive set of known mixture spectra, which is difficult to produce for a two-phase effluent stream of a reacting system.…”

Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

“…24,25 PEAXACT spectral processing software is used to perform IHM. Quantitative calibration of Raman spectra is achieved via an indirect methodology closely aligned with that described by Beumers et al 26 where an elemental balance of reactor inputs and outputs is used to achieve calibration. Experimental temperature is varied from 500 to 560 °C, with residence times from 3 to 8 s for each alcohol at each temperature.…”

“…Indirect hard modeling (IHM) is used for accurate quantitative Raman spectroscopy for calculating product yields. , PEAXACT spectral processing software is used to perform IHM. Quantitative calibration of Raman spectra is achieved via an indirect methodology closely aligned with that described by Beumers et al where an elemental balance of reactor inputs and outputs is used to achieve calibration.…”

Hydrolysis of Dimethyl Methylphosphonate (DMMP) in Hot-Compressed Water

“…Indirect hard modeling (IHM) is used to extract species concentration from collected Raman spectra. , IHM facilitates quantitative analysis of overlapping Raman signals, via a weighted superposition of the pure spectra of constituent species. Quantitative calibration between Raman spectra and product concentrations is achieved via an indirect methodology described by Beumers et al, where a least-square optimization of elemental balances between reactor inputs and outputs is used to perform calibration. For each pure compound, a linear correlation between the spectral area and predicted species concentration is observed, verifying calibration accuracy.…”