Nous observons par diffusion de neutrons aux petits angles la structure de chaines de polystyrene en solution semi-diluee confinees dans un milieu poreux modele, le Vycor. La taille des chaines en solution a l'etat libre est toujours superieure au diametre des pores, 70 A. L'utilisation d'un melange adequat de solvants et de polymeres hydrogenes et deuteres nous permet de mesurer directement le facteur de forme d'une seule chaine au milieu des autres. La penetration des chaines dans le milieu poreux est presque totale pour la concentration (Φ = 20%) et la gamme de poids moleculaire (35 000 < M w < 800 000) utilisees. Le rayon de gyration des chaines confinees est toujours inferieur au rayon de gyration des chaines libres dans la solution equivalente. Nos mesures sont en accord avec les predictions theoriques etablies par Daoud et de Gennes pour des chaines confinees dans un pore cylindrique quand les chaines sont enchevetrees et comprimees transversalement mais restent ideales a grande echelle dans la direction du cylindre a cause de l'ecrantage du volume exclus (regime dit de cigares semi-dilues). Les valeurs des coefficients de partage des chaines entre le milieu poreux et la solution libre ainsi que le comportement asymptotique des facteurs de structure montrent que le polystyrene s'adsorbe sur la surface nue du Vycor. Nous montrons que la silanisation du Vycor supprime cette adsorption.
通过中子在小角度的扩散，我们观察了聚苯乙烯链在半稀释溶液中的结构，该溶液被限制在一个模型多孔介质Vycor中。在自由状态下，链的尺寸总是大于孔隙直径70 a。通过使用溶剂和氢和氘聚合物的适当混合物，我们可以直接测量一条链中间的形状因子。多孔介质中渗透频道几乎完全是为了集中(Φ分子= 20%)和体重范围(35 000 M w < 800 000)边。在等效解中，约束链的旋回半径始终小于自由链的旋回半径。我们这些措施符合理论predictions艾弗森(由Daoud confinees频道和chastel为了在一个圆柱形毛孔当频道enchevetrees且comprimees直角但依然达到了数值轴方向的大型缸由于l’ecrantage排除体积(regime雪茄semi-dilues)说。多孔介质与自由溶液之间的链分布系数和结构因子的渐近行为表明，聚苯乙烯吸附在Vycor的裸露表面。我们证明了Vycor的硅烷化消除了这种吸附。
{"title":"Structure of Polymer Chains Confined in Vycor","authors":"J. Lal, S. Sinha, L. Auvray","doi":"10.1051/JP2:1997205","DOIUrl":"https://doi.org/10.1051/JP2:1997205","url":null,"abstract":"Nous observons par diffusion de neutrons aux petits angles la structure de chaines de polystyrene en solution semi-diluee confinees dans un milieu poreux modele, le Vycor. La taille des chaines en solution a l'etat libre est toujours superieure au diametre des pores, 70 A. L'utilisation d'un melange adequat de solvants et de polymeres hydrogenes et deuteres nous permet de mesurer directement le facteur de forme d'une seule chaine au milieu des autres. La penetration des chaines dans le milieu poreux est presque totale pour la concentration (Φ = 20%) et la gamme de poids moleculaire (35 000 < M w < 800 000) utilisees. Le rayon de gyration des chaines confinees est toujours inferieur au rayon de gyration des chaines libres dans la solution equivalente. Nos mesures sont en accord avec les predictions theoriques etablies par Daoud et de Gennes pour des chaines confinees dans un pore cylindrique quand les chaines sont enchevetrees et comprimees transversalement mais restent ideales a grande echelle dans la direction du cylindre a cause de l'ecrantage du volume exclus (regime dit de cigares semi-dilues). Les valeurs des coefficients de partage des chaines entre le milieu poreux et la solution libre ainsi que le comportement asymptotique des facteurs de structure montrent que le polystyrene s'adsorbe sur la surface nue du Vycor. Nous montrons que la silanisation du Vycor supprime cette adsorption.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"15 1","pages":"1597-1615"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81702253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We studied the sequence of phenomena which occur when a solid microsphere is brought in contact with an isolated giant lipid vesicle. We used Latex beads, a few microns in diameter, which were manipulated individually by means of a long-working-distance optical trap. The evolution of the bead/vesicle system was characterized in time, from ∼ 1 ms to ∼ 100 s. In this time range, we identified different steps, namely adhesion, ingestion, expulsion and re-capture. In the adhesion step the sphere moves quickly in direction to the vesicle interior and the surface of the particle becomes wetted by lipids. We propose a simple model, based on the counter-balance between adhesion and stretching of the lipid lamella, which explains the experimental equilibrium configuration. The bead/vesicle configuration after the adhesion step pertains to partial or complete wetting, depending on the initial vesicle state. Partial wetting can be followed by a second step, which we named particle ingestion, and which leads to complete (or nearly complete) wetting of the particle surface. Ingestion is characterized by a further penetration of the particle across the vesicle contour, in concomitance with a decrease of the vesicle size. The phenomenon is attributed to the occurrence of a dynamically stabilized pore across the membrane, which allows part of the water initially inside the vesicle to flow out. Ingestion can be followed by a back and forth movement (expulsion and re-capture) of the particle. In the ultimate configuration, the solid surface is totally wetted by lipids, however with a finite contact angle between the membrane and the solid surface.
{"title":"Adhesion of Latex Spheres to Giant Phospholipid Vesicles: Statics and Dynamics","authors":"Christian, Dietrich, Miglena, Angelova, Bernard, Pouligny","doi":"10.1051/JP2:1997208","DOIUrl":"https://doi.org/10.1051/JP2:1997208","url":null,"abstract":"We studied the sequence of phenomena which occur when a solid microsphere is brought in contact with an isolated giant lipid vesicle. We used Latex beads, a few microns in diameter, which were manipulated individually by means of a long-working-distance optical trap. The evolution of the bead/vesicle system was characterized in time, from ∼ 1 ms to ∼ 100 s. In this time range, we identified different steps, namely adhesion, ingestion, expulsion and re-capture. In the adhesion step the sphere moves quickly in direction to the vesicle interior and the surface of the particle becomes wetted by lipids. We propose a simple model, based on the counter-balance between adhesion and stretching of the lipid lamella, which explains the experimental equilibrium configuration. The bead/vesicle configuration after the adhesion step pertains to partial or complete wetting, depending on the initial vesicle state. Partial wetting can be followed by a second step, which we named particle ingestion, and which leads to complete (or nearly complete) wetting of the particle surface. Ingestion is characterized by a further penetration of the particle across the vesicle contour, in concomitance with a decrease of the vesicle size. The phenomenon is attributed to the occurrence of a dynamically stabilized pore across the membrane, which allows part of the water initially inside the vesicle to flow out. Ingestion can be followed by a back and forth movement (expulsion and re-capture) of the particle. In the ultimate configuration, the solid surface is totally wetted by lipids, however with a finite contact angle between the membrane and the solid surface.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"25 1","pages":"1651-1682"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83655781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Rencontres Physique-Biologie-Chimie de la montagne Sainte-Genevieve 1997 François Amblard, Pascal Silberzan, V. Croquette
它是一个多学科的开放获取档案，用于科学研究文件的存储和传播，无论它们是否出版。这些文件可能来自法国或国外的教学和研究机构，也可能来自公共或私人研究中心。HAL开放多学科档案旨在存放和传播来自法国或外国教育和研究机构、公共或私人实验室的已发表或未发表的研究级科学文件。物理-生物-化学会议saint - genevieve 1997 francois Amblard, Pascal Silberzan, V. Croquette
{"title":"Rencontres Physique-Biologie-Chimie de la montagne Sainte-Genevieve 1997","authors":"F. Amblard, P. Silberzan, V. Croquette","doi":"10.1051/JP2:1997203","DOIUrl":"https://doi.org/10.1051/JP2:1997203","url":null,"abstract":"HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Rencontres Physique-Biologie-Chimie de la montagne Sainte-Genevieve 1997 François Amblard, Pascal Silberzan, V. Croquette","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"11 1","pages":"1555-1575"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90955235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report experimental studies on the effect of a strong electric field on the nematic-smectic A d (N-A d ) and A -reentrant nematic (A d -N R ) phase transitions in a binary mixture. Both the transition temperatures increase with field. The A -N transition point changes much more rapidly than that of A d -N transition, indicating that the A d phase will get bounded at a sufficiently high field. We have included the effect of the electric field in our molecular model of reentrant phases in highly polar compounds, in which the mutual orientation of near neighbour molecules changes from an antiparallel to a parallel configuration as the temperature is lowered. It is argued that the cross-over temperature increases with field which accounts for the observed trends. For suitable parameters, it is also predicted that either a nematic-nematic transition line can branch off from the A d -N R line or a smectic A-smectic A transition line can meet the A d -N R line at an appropriate field. In the latter case, the A d -N R line has an associated slope change which is consistent with the experimental data.
本文报道了强电场对二元混合物中向列-近向列(N-A - d)和重入向列(a - d -N - R)相变影响的实验研究。两者的转变温度均随电场增大而增大。A -N跃迁点的变化要比A - d -N跃迁点的变化快得多，这表明在足够高的场下，A - d相会有界。我们在高极性化合物的重入相分子模型中考虑了电场的影响，在重入相中，随着温度的降低，邻近分子的相互取向从反平行变为平行。认为交叉温度随场增大而增大，这解释了观测到的趋势。在适当的参数下，还预测了向列-向列过渡线可以从a -N - R线分支出来，或者在适当的场处，a - a -s - a过渡线可以满足a -N - R线。后一种情况下，A d -N R线有相应的斜率变化，这与实验数据一致。
{"title":"Effect of a Strong Electric Field on the Reentrant Nematic to Smectic Ad Phase Transition","authors":"G. Basappa, A. S. Covind, N. V. Madhusudana","doi":"10.1051/JP2:1997210","DOIUrl":"https://doi.org/10.1051/JP2:1997210","url":null,"abstract":"We report experimental studies on the effect of a strong electric field on the nematic-smectic A d (N-A d ) and A -reentrant nematic (A d -N R ) phase transitions in a binary mixture. Both the transition temperatures increase with field. The A -N transition point changes much more rapidly than that of A d -N transition, indicating that the A d phase will get bounded at a sufficiently high field. We have included the effect of the electric field in our molecular model of reentrant phases in highly polar compounds, in which the mutual orientation of near neighbour molecules changes from an antiparallel to a parallel configuration as the temperature is lowered. It is argued that the cross-over temperature increases with field which accounts for the observed trends. For suitable parameters, it is also predicted that either a nematic-nematic transition line can branch off from the A d -N R line or a smectic A-smectic A transition line can meet the A d -N R line at an appropriate field. In the latter case, the A d -N R line has an associated slope change which is consistent with the experimental data.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"18 1","pages":"1693-1707"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90102180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Les effets d'une perturbation mecanique appliquee parallelement au plan des couches smectiques d'un film librement suspendu sont etudies a partir d'un nouveau dispositif experimental. Les experiences sont realisees sur des films de differentes epaisseurs dans les phases smectiques dites liquides, hexatiques et cristallines. Nous montrons que la phase thermodynanique du menisque est un parametre crucial car il determine le regime de perturbation que subit le film. En s'appuyant sur un modele phenomenologique, nous distinguons deux regimes de perturbation : le regime d'ecoulement et le regime elastique. Les mesures effectuees dans ce dernier cas nous permettent d'extraire la valeur de la constante elastique dans les phases cristallines smectique B et smectique G. La forte variation du coefficient de compressibilite observee entre ces deux phases indique que l'angle d'inclinaison des molecules apporte au film une variable macroscopique supplementaire pour repondre a la perturbation mecanique imposee.
{"title":"Mechanical Properties of Freely Suspended Smectic Films","authors":"I. Kraus, C. Bahr, P. Pieranski","doi":"10.1051/JP2:1997206","DOIUrl":"https://doi.org/10.1051/JP2:1997206","url":null,"abstract":"Les effets d'une perturbation mecanique appliquee parallelement au plan des couches smectiques d'un film librement suspendu sont etudies a partir d'un nouveau dispositif experimental. Les experiences sont realisees sur des films de differentes epaisseurs dans les phases smectiques dites liquides, hexatiques et cristallines. Nous montrons que la phase thermodynanique du menisque est un parametre crucial car il determine le regime de perturbation que subit le film. En s'appuyant sur un modele phenomenologique, nous distinguons deux regimes de perturbation : le regime d'ecoulement et le regime elastique. Les mesures effectuees dans ce dernier cas nous permettent d'extraire la valeur de la constante elastique dans les phases cristallines smectique B et smectique G. La forte variation du coefficient de compressibilite observee entre ces deux phases indique que l'angle d'inclinaison des molecules apporte au film une variable macroscopique supplementaire pour repondre a la perturbation mecanique imposee.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"26 1","pages":"1617-1634"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91229646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate the closed flow between coaxial contra rotating disks, at moderate to high Reynolds numbers. We show that global (i.e. spatially averaged) quantities can be used to characterize the state of the flow and its degree of turbulence. We first report measurements on the driving torque and show how it depends on the manner momentum is imparted to the fluid. We then show that pressure measurements at the flow boundary provide a good estimate of the rms velocity fluctuations in the flow and that it reveals the transition to turbulence in the flow volume. Finally, we show that once the transition has occurred, the knowledge of the same global quantities allows the calculation of fundamental turbulence characteristics such as the rms velocity fluctuations, the effective integral length scale L * , Taylor's microscale λ and Kolmogorov's dissipation length η. That these quantities may be obtained from measuring devices removed from the bulk of the flow is of importance for the study of fluid motion in complex geometries and/or using corrosive fluids
{"title":"Characterization of Turbulence in a Closed Flow","authors":"N. Mordant, J. Pinton, F. Chillà","doi":"10.1051/JP2:1997212","DOIUrl":"https://doi.org/10.1051/JP2:1997212","url":null,"abstract":"We investigate the closed flow between coaxial contra rotating disks, at moderate to high Reynolds numbers. We show that global (i.e. spatially averaged) quantities can be used to characterize the state of the flow and its degree of turbulence. We first report measurements on the driving torque and show how it depends on the manner momentum is imparted to the fluid. We then show that pressure measurements at the flow boundary provide a good estimate of the rms velocity fluctuations in the flow and that it reveals the transition to turbulence in the flow volume. Finally, we show that once the transition has occurred, the knowledge of the same global quantities allows the calculation of fundamental turbulence characteristics such as the rms velocity fluctuations, the effective integral length scale L * , Taylor's microscale λ and Kolmogorov's dissipation length η. That these quantities may be obtained from measuring devices removed from the bulk of the flow is of importance for the study of fluid motion in complex geometries and/or using corrosive fluids","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"120 1","pages":"1729-1742"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78656426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Lescop, M. Arfa, G. L. Coz, M. Cherid, G. Sinou, G. Fanjoux, A. Nadan, F. Tuffin
Penning ionization electron spectroscopy of the CO molecule by He*(2 1 S) metastable atoms is studied. Vibrational populations are reported for the three energetically accessible states of the CO + ion (X 2 Σ + , A 2 Π and B 2 Σ + ). An obvious discrepancy is observed between the excited vibrational levels of the X 2 Σ + state and the calculated Franck-Condon factors. This result is attributed to an excitation transfer process via Rydberg vibrational progression converging to the CO + (D 2 Π) ionic state in agreement with the recent observations by fluorescence of neutral dissociate states. The presence of electrons coming from the well-known σ shape resonance is not excluded.
{"title":"Excitation Transfer Process in Penning Ionization of the CO Molecule by Helium Atoms in Singlet Metastable State","authors":"B. Lescop, M. Arfa, G. L. Coz, M. Cherid, G. Sinou, G. Fanjoux, A. Nadan, F. Tuffin","doi":"10.1051/jp2:1997202","DOIUrl":"https://doi.org/10.1051/jp2:1997202","url":null,"abstract":"Penning ionization electron spectroscopy of the CO molecule by He*(2 1 S) metastable atoms is studied. Vibrational populations are reported for the three energetically accessible states of the CO + ion (X 2 Σ + , A 2 Π and B 2 Σ + ). An obvious discrepancy is observed between the excited vibrational levels of the X 2 Σ + state and the calculated Franck-Condon factors. This result is attributed to an excitation transfer process via Rydberg vibrational progression converging to the CO + (D 2 Π) ionic state in agreement with the recent observations by fluorescence of neutral dissociate states. The presence of electrons coming from the well-known σ shape resonance is not excluded.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"9 1","pages":"1543-1554"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86372124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Nyrkova, A. Semenov, A. Khokhlov, K. Linliu, B. Chu
The viscosity of a fluid can be measured by observing the motion of a probe sphere (or ball) in a centrifuge tube filled with this fluid. The hydrodynamic behavior of the probe ball moving in the centrifuge tube has been solved theoretically. We have got the universal relationship (for balls of a given material and size in a given tube) between the terminal ball velocity, the fluid viscosity and the centrifuge acceleration using the only adjustable parameter - the rotational friction coefficient between the ball and the tube. The rotation of the centrifuge tube in the horizontal plane induces an inertia force which is counterbalanced by the friction force acting on the ball. As a result, the ball moves along the tube with some characteristic speed, which is a measure of the viscosity of the fluid. This speed was calculated in the lubrication approximation. The gravitational acceleration causes the ball to move very close to the bottom of the centrifuge tube. In this situation, the gravity is balanced by a levitation force introduced and calculated in the present paper. The origin of this force is the formation of the bubble behind and below the moving ball. The theoretical development on the terminal velocity for the ball moving very near the bottom of the horizontal centrifuge tube is tested by using a specially designed centrifuge for two types of balls and a wide set of viscosity standards. Excellent agreement between theory and experiment suggests that we have developed a new approach to measure high viscosities of fluids at low shear rates which might be especially useful for the investigation of polymer melts.
{"title":"Motion of a Probe Ball in the Fluid under Centrifugal Acceleration","authors":"I. Nyrkova, A. Semenov, A. Khokhlov, K. Linliu, B. Chu","doi":"10.1051/JP2:1997211","DOIUrl":"https://doi.org/10.1051/JP2:1997211","url":null,"abstract":"The viscosity of a fluid can be measured by observing the motion of a probe sphere (or ball) in a centrifuge tube filled with this fluid. The hydrodynamic behavior of the probe ball moving in the centrifuge tube has been solved theoretically. We have got the universal relationship (for balls of a given material and size in a given tube) between the terminal ball velocity, the fluid viscosity and the centrifuge acceleration using the only adjustable parameter - the rotational friction coefficient between the ball and the tube. The rotation of the centrifuge tube in the horizontal plane induces an inertia force which is counterbalanced by the friction force acting on the ball. As a result, the ball moves along the tube with some characteristic speed, which is a measure of the viscosity of the fluid. This speed was calculated in the lubrication approximation. The gravitational acceleration causes the ball to move very close to the bottom of the centrifuge tube. In this situation, the gravity is balanced by a levitation force introduced and calculated in the present paper. The origin of this force is the formation of the bubble behind and below the moving ball. The theoretical development on the terminal velocity for the ball moving very near the bottom of the horizontal centrifuge tube is tested by using a specially designed centrifuge for two types of balls and a wide set of viscosity standards. Excellent agreement between theory and experiment suggests that we have developed a new approach to measure high viscosities of fluids at low shear rates which might be especially useful for the investigation of polymer melts.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"32 1","pages":"1709-1728"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88112623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Static and dynamic light scattering measurements, all using circularly polarized light, are used to investigate the third blue phase to isotropic liquid critical point in a mixture of S, S–$4''$(methylbutyl)phenyl–4'–(methylbutyl)biphenylcarboxylate (S,S-MBBPC) and its racemate. The intensity of light scattering and the relaxation time for the most strongly fluctuating chiral mode are found to be significantly greater than in a supercritical mixture of S,S-MBBPC. While the increase is substantial, there is no indication that any true divergence in these quantities is present. The results can qualitatively be explained by the simple phenomenological theory of Lubensky and Stark [3], which places this transition in the same universality class as the liquid-gas transition.
{"title":"Static and Dynamic Light Scattering Near the Liquid Crystalline Blue Phase III – Isotropic Liquid Critical Point","authors":"U. Singh, P. Collings, C. Booth, J. Goodby","doi":"10.1051/JP2:1997209","DOIUrl":"https://doi.org/10.1051/JP2:1997209","url":null,"abstract":"Static and dynamic light scattering measurements, all using circularly polarized light, are used to investigate the third blue phase to isotropic liquid critical point in a mixture of S, S–$4''$(methylbutyl)phenyl–4'–(methylbutyl)biphenylcarboxylate (S,S-MBBPC) and its racemate. The intensity of light scattering and the relaxation time for the most strongly fluctuating chiral mode are found to be significantly greater than in a supercritical mixture of S,S-MBBPC. While the increase is substantial, there is no indication that any true divergence in these quantities is present. The results can qualitatively be explained by the simple phenomenological theory of Lubensky and Stark [3], which places this transition in the same universality class as the liquid-gas transition.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"19 1","pages":"1683-1691"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75508919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Monkade, P. Martinot-Lagarde, G. Durand, C. Granjean
We present transmission electron microscopy micrographs of SiO films obliquely evaporated on indium-tin oxide coated glass surfaces. To study the growth mechanism of these SiO films, we present film cross sections in the evaporation plane. Varying the evaporation angle, we observe a column to needle transition, with increasing surface roughness. This transition corresponds to the planar to oblique nematic liquid crystal orientation transition, through the bistable one. The SiO surface roughness is estimated to induce a nematic surface order decrease (surface melting). The azimuthal nematic orientation on these plates corresponds to the direction of minimum surface melting. This confirms the predictions of the Barbero-Durand model.
{"title":"SiO Evaporated Films Topography and Nematic Liquid Crystal Orientation","authors":"M. Monkade, P. Martinot-Lagarde, G. Durand, C. Granjean","doi":"10.1051/JP2:1997204","DOIUrl":"https://doi.org/10.1051/JP2:1997204","url":null,"abstract":"We present transmission electron microscopy micrographs of SiO films obliquely evaporated on indium-tin oxide coated glass surfaces. To study the growth mechanism of these SiO films, we present film cross sections in the evaporation plane. Varying the evaporation angle, we observe a column to needle transition, with increasing surface roughness. This transition corresponds to the planar to oblique nematic liquid crystal orientation transition, through the bistable one. The SiO surface roughness is estimated to induce a nematic surface order decrease (surface melting). The azimuthal nematic orientation on these plates corresponds to the direction of minimum surface melting. This confirms the predictions of the Barbero-Durand model.","PeriodicalId":14774,"journal":{"name":"Journal De Physique Ii","volume":"28 1","pages":"1577-1596"},"PeriodicalIF":0.0,"publicationDate":"1997-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85135663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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