Experimental observation of critical depolarization in carbon dioxide

Trappeniers, N.J.; Michels, Andreas; Huijser, R.H.

doi:10.1016/0009-2614(75)80234-x

Cited by 22 publications

(9 citation statements)

References 9 publications

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“…Several other effects can be shown to become possible in addition to those mentioned above: (1) far enough from the critical point, the 1.5-scattering alone causes the depolarization ratio to increase with temperature by the law ∆ ∝ β, typical of the true double scattering mechanism; (2) the joint action of the 1.5-scattering and the true double scattering mechanisms causes the divergence of ∆ with β to become stronger in the temperature range τ 10 −3 (such an increase was observed in [7], but was attributed to triple light scattering); (3) subsequently, the increase of ∆ may change to a decrease at τ 10 −4 (such a decrease was indeed observed in [20], but was subjected to question). The details of the pertinent analysis will be published elsewhere.…”

Section: Resultsmentioning

confidence: 99%

“…Then, in view of formulae (17), (19), (20), and (22), the relative magnitude of I 1.5 , as compared to those of I 1 , I 2 , and I d , changes with temperature as…”

Section: Estimates With the Van Der Waals Modelmentioning

confidence: 99%

“…In view of formulas (17), (19), (20), (22), and the positivity of the contributions I 1 , I d , I dd , and I a , its structure is…”

Section: Experimental Data Analysismentioning

confidence: 99%

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1.5-multiplicity molecular light scattering in fluids?

Sushko¹

2006

Condens. Matter Phys.

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The third-order thermodynamic moment of the density fluctuations is shown to contribute notably to the molecular light scattering in a single-component fluid. The relevant 1.5-scattering is expected to affect the depolarization ratio of the scattered light as the scattering is studied near the critical isochore and for the temperature interval where nonlocal correlation between fluctuations is relatively weak. The experimental data in support of this conclusion are quoted.

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Section: Resultsmentioning

confidence: 99%

“…Then, in view of formulae (17), (19), (20), and (22), the relative magnitude of I 1.5 , as compared to those of I 1 , I 2 , and I d , changes with temperature as…”

Section: Estimates With the Van Der Waals Modelmentioning

confidence: 99%

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1.5-multiplicity molecular light scattering in fluids?

Sushko¹

2006

Condens. Matter Phys.

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“…The two-body double scattering (5.33) belongs naturally with a four-body term coming from the corrected first term of figure 4 f .In a first, somewhat intuitive, microscopic tr macroscopic multiple scattering Oxtoby & Gelbart (1974a, b) have already analysed contributions that may be said to be contained in this four-body term. These authors, and subsequently Boots et al (1976) give estimates of the contribution to double scattering Experimental depolarization studies, which appear to illustrate the behaviour of macroscopic multiple scattering close to the critical point, have been published by Reith & Swiney (1975) for xenon and by Trappeniers et al (1975) for carbon dioxide. We find the theoretical situation close to the critical point so complicated that at most only a qualitative interpretation is possible there.…”

Section: R(xmentioning

confidence: 94%

The scattering of light. III. External scattering from a finite molecular fluid

Hynne

Bullough

1990

Phil. Trans. R. Soc. Lond. A

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We calculate the external incoherent scattering from a finite molecular fluid exposed to a weak, external, coherent electromagnetic field. The scattered field is detected outside the fluid and the system models a real scattering experiment in all its aspects. The analysis is based on a classical all order many-body theory developed in two previous papers. The theory is microscopic, i.e. is developed ab initio and in detail in terms of individual scattering processes in vacuo at a strictly molecular level. But it is shown that the collective action of these generates all of the macroscopic features expected in the external scattering: for example, the refractive index, as it was calculated previously from the many-body theory, plays much of its expected macroscopic role. These macroscopic results are reached by showing that the complete scattering process (from a wave incident in vacuo on the fluid to a wave in vacuo scattered from the fluid) separates into three independent collective processes compactly described by a particular quadrilinear form quadratic in a field $ induced in the fluid by any coherent external field, and quadratic in a ‘weight’ field e describing the scattered field in the fluid. The internal fields $ and e couple separately to the external incoming field and to one representing the external scattered field respectively. In each case they account for all collective surface effects. The kernel of the quadrilinear form accounts for all of the internal scattering processes in the fluid. The weight field e and the equations associated with it describe refraction and (multiple) internal reflection of the scattered light at the surface of the medium in all details: these collective surface effects are managed in a very effective way through a new reciprocity principle derived from the microscopic theory and containing a new form of optical extinction theorem for external scattering. The kernel of the quadrilinear form for internal scattering has a natural expansion describing macroscopic single and macroscopic multiple scattering agreeing with phenomenological ideas. The expansion is derived from a relation between the weight field and a propagator for the scattered wave. We show that macroscopic single scattering contains processes displaying ‘backscattering coherence’. This phenomenon has not been recognized in molecular scattering theory before, and back-scattering enhancement very much like that recently observed in scattering from suspensions of dielectric particles, should be observable near a critical point of phase separation. We give explicit formulae for macroscopic single scattering from a dilute gas up to two-body contributions with intermolecular correlations determined by a LennardJones potential. We also show how Einstein’s phenomenological single scattering formula can be derived from certain microscopic scattering processes of all orders. With a minor qualification the formula is valid in a generalized form up to neglect of terms of order six in the polarizability per unit volume.

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“…Une etude du meme type a d'ailleurs ete faite sur CO2 au point critique par Trappeniers et coll. [38]. Ils mettent en evidence la diffusion multiple, c'est-a-dire les termes tres longue portee de l'interaction D.I.D.…”

Section: Etude De La Depolarisation En Fonction Deunclassified

Effets des chocs multiples sur la diffusion de la lumière dans l'argon, le méthane, l'azote et l'éthylène gazeux

et al. 1976

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2014 On étudie la diffusion de la lumière par des gaz comprimés jusqu'à 200 bar, en fonction de la densité. Dans le cas des molécules isotropes, on met en évidence les effets des collisions triples et d'ordre supérieur. On montre que ces effets sont correctement décrits par les calculs d'Alder et coll. en dynamique moléculaire. Pour les molécules anisotropes, nous avons pu séparer la contribution de l'anisotropie propre et de l'anisotropie collisionnelle à la diffusion dépolarisée. Les hyperpolarisabilités collisionnelles sont principalement dues aux effets de champ de longue portée. Abstract. 2014 We have studied the scattering of light in these gases up to 200 atm. In the case of isotropic molecules, one sees évidence of triple and higher order collisions. We show that these effects are correctly described by the molecular dynamics calculations of Alder and co-workers. In the case of anisotropic molecules, we have been able to separate the effects of intrinsic anisotropy from that induced by collisions. The collision induced polarizabilities seem to be mainly due to long range local field effects.

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Experimental observation of critical depolarization in carbon dioxide

Cited by 22 publications

References 9 publications

1.5-multiplicity molecular light scattering in fluids?

1.5-multiplicity molecular light scattering in fluids?

The scattering of light. III. External scattering from a finite molecular fluid

Effets des chocs multiples sur la diffusion de la lumière dans l'argon, le méthane, l'azote et l'éthylène gazeux

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