A high-pressure high-temperature setup for in situ Raman spectroscopy of supercritical fluids

Louvel, Marion; Bordage, Amélie; Silva-Cadoux, Cécile Da; Testemale, Denis; Lahéra, Eric; Net, William Del; Geaymond, Olivier; Dubessy, Jean; Argoud, R.; Hazemann, Jean‐Louis

doi:10.1016/j.molliq.2014.09.032

Cited by 19 publications

(11 citation statements)

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“…Thereby, to identify the current state of matter, it is especially important to have a robust and simple diagnostic tool. The clustering of molecules that occurs in supercritical fluid leads to the modification in the molecular refraction, an increase of the nonlinear refractive index [ 18 ] and the offset of the rotational–vibrational transitions [ 19 ]. Specific modifications in the SCF microstructure can be detected by optical techniques such as Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…IR and Raman spectroscopy are also widely used to investigate different samples from inorganic materials to complex organic structures [ 20 ]. Previously, Raman and coherent anti-stokes Raman scattering (CARS) spectroscopy were applied for scCO 2 investigations [ 19 , 21 , 22 ]. However, the anomalous properties of the Raman spectra in the Widom line vicinity were not highlighted.…”

Section: Introductionmentioning

confidence: 99%

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Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

et al. 2020

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The supercritical CO2 (scCO2) is widely used as solvent and transport media in different technologies. The technological aspects of scCO2 fluid applications strongly depend on spatial–temporal fluctuations of its thermodynamic parameters. The region of these parameters’ maximal fluctuations on the p-T (pressure-temperature) diagram is called Widom delta. It has significant practical and fundamental interest. We offer an approach that combines optical measurements and molecular dynamics simulation in a wide range of pressures and temperatures. We studied the microstructure of supercritical CO2 fluid and its binary mixture with ethanol in a wide range of temperatures and pressures using molecular dynamics (MD) simulation. MD is used to retrieve a set of optical characteristics such as Raman spectra, refractive indexes and molecular refraction and was verified by appropriate experimental measurements. We demonstrated that in the Widom delta the monotonic dependence of the optical properties on the CO2 density is violated. It is caused by the rapid increase of density fluctuations and medium-sized (20–30 molecules) cluster formation. We identified the correlation between cluster parameters and optical properties of the media; in particular, it is established that the clusters in the Widom delta acts as a seed for clustering in molecular jets. MD demonstrates that the cluster formation is stronger in the supercritical CO2-ethanol mixture, where the extended binary clusters are formed; that is, the nonlinear refractive index significantly increased. The influence of the supercritical state in the cell on the formation of supersonic cluster jets is studied using the Mie scattering technique.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

et al. 2020

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“…The rather weak Raman scattering efficiency of water molecule might cause detrimental impact on the accuracy of water concentration determination. 30 More so, even though Raman spectrum of water at ambient conditions is well-known in the O-H stretching region, the quantity of distinguishable spectral features and their intensity experience a steady decrease as temperature rises. 31 In light of this, accurate determination of water concentration with Raman spectroscopy might be especially challenging since gas composition analysis is typically performed at elevated temperatures to avoid vapor condensation.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Gas phase methanol synthesis with Raman spectroscopy for gas composition monitoring

et al. 2020

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“…There, the idea is to put a tube containing the precursor solution and pistons in both ends inside the autoclave. When the pressure increases, the pistons move to compress the solution inside the tube [15,16]. This strategy does not provide a full access to the reactor over 360°, since there is a need to implement windows in the autoclave, limiting the angular access to the tube.…”

Section: In Situ Characterization Techniquesmentioning

confidence: 99%

Playing with chemistry in supercritical solvents and the associated technologies for advanced materials by design

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Philippot

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et al. 2018

The Journal of Supercritical Fluids

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This publication concerns the design of advanced nanostructured inorganic materials using supercritical fluids. A brief overview of the different experimental and numerical tools, which are now available for the scientific community and engineers, is proposed giving access to a better understanding but also a better control on material synthesis. The versatility of the supercritical fluids route for the preparation of different natures of inorganic materials is emphasized based on the access to numerous solvents, precursors and their associated chemistries. It is possible to produce materials with physicochemical properties, which can not be obtained with other routes and at large scale. All these chemistries give access to a wide range of nanobricks opening a new area for the preparation of advanced materials by design through the development of one pot multistep processes.

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A high-pressure high-temperature setup for in situ Raman spectroscopy of supercritical fluids

Cited by 19 publications

References 70 publications

Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

Gas phase methanol synthesis with Raman spectroscopy for gas composition monitoring

Playing with chemistry in supercritical solvents and the associated technologies for advanced materials by design

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