Superior mirage effect in supercritical CO 2: Experiment and model

At temperatures near T c, supercritical CO 2 is highly compressible and it follows that a small temperature gradient will create a large density gradient. We established stable density gradients by maintaining the bottom of a sc-CO 2-cell cooler than its other sides. That created a large refractive...

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Bibliographic Details
Published inThe Journal of supercritical fluids Vol. 35; no. 3; pp. 260 - 264
Main Authors Jain, Jatin P., Rothe, Erhard W.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 2005
Subjects
Beam deflection
Carbon dioxide
Mirage
Refractive index
Supercritical
Supercritical
Beam deflection
Refractive index
Carbon dioxide
Mirage
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Summary:At temperatures near T c, supercritical CO 2 is highly compressible and it follows that a small temperature gradient will create a large density gradient. We established stable density gradients by maintaining the bottom of a sc-CO 2-cell cooler than its other sides. That created a large refractive index gradient that bent a laser beam through an angle that is roughly proportional to the density gradient. Such light bending causes, for example, the mirage of water on a hot road. A He–Ne laser beam traversed a 7.62 cm long cell and was deflected downward as much as 5.9°. The magnitude of the beam deflections agreed within 3% with a model that used only fundamental geometrical optics and known PVT data, but that employed no adjustable parameters.
ISSN:0896-8446
1872-8162
DOI:10.1016/j.supflu.2005.02.001