Hochdruck-Raman-Lichtstreuexperimente an überkritischem Cyclopropan und Stickstoff-Xenon-Gemischen in einem weiten Dichtebereich

Studies on supercritical Cyclopropane and on supercritical Nitrogen-Xenon-mixtures in an entire range of compositions and densities were done using high-pressure depolarized Raman spectroscopy. The results were compared to those of molecular dynamics-(MD)-simulations-studies. As far as possible the interpretation of the experimental results was performed without using MD-results. There was a good coincidence between the experimental and MD-simulation results. The Raman-time-correlation-functions (TCF) of the oblate Cyclopropane molecule were investigated in a range of reduced density: 0,25<= Rho r = Rho / Rho c <= 2,00 at a temperature of T = 413 K. There are no interaction-induced contributions to the scattered light, whereas the Rayleigh-TCF are dominated by collision-induced (CI) contributions. These contributions are depending on the reduced density and there is a significant deviation of the reduced second spectral moments from its value for an ensemble of free classical rotators. Concerning the CI-terms one can observe a cancellation effect with increasing density. The Nitrogen-Xenon-mixtures were investigated in a range of density 0,65 10-2 mol cm-3 <= Rho<=2,25 10-2 mol cm-3 and at a temperature of T = 323 K. Even for high densities the Raman spectra showed the shape of reorientational Nitrogen spectra. The highly polarizable spherical particle Xenon is in this case an optically indifferent diluent. On the other hand there are significant CI-contributions in the Rayleigh spectra which become more prominent with increasing Xenon molefraction. The value of the reduced second moment decreases dramatically. Results of MD-simulations show that the reorientational behaviour of the Nitrogen molecules is not inhibited even in Xenon-rich mixtures and at high densities.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Collet, Bernhard Johannes

Contributors dc:contributor

• Versmold, Heinrich

• info:eu-repo/classification/ddc/540
• Chemie
• Hochdruck
• Raman-Lichtstreuung
• überkritische Fluide

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-119203%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:57135