Experimental observation of triple correlations in fluids

TL;DR

This paper provides experimental evidence for triple correlations in fluid density fluctuations, observed via molecular spectroscopy, especially near the critical point, revealing new insights into fluid scattering phenomena.

Contribution

It demonstrates the detection of triple correlations in fluids through 1.5-scattering measurements, a novel experimental approach in this context.

Findings

Triple correlations manifest as 1.5-scattering near the critical point.

Experimental data supports the presence of these correlations.

Implications for understanding fluid fluctuation behavior are discussed.

Abstract

We present arguments for the hypothesis that under some conditions, triple correlations of density fluctuations in fluids can be detected experimentally by the method of molecular spectroscopy. These correlations manifest themselves in the form of the so-called 1.5- (i.e., sesquialteral) scattering. The latter is of most significance in the pre-asymptotic vicinity of the critical point and can be registered along certain thermodynamic paths. Its presence in the overall scattering pattern is demonstrated by our processing experimental data for the depolarization factor. Some consequences of these results are discussed.