Measuring the nematic order of suspensions of colloidal fd virus by x-ray diffraction and optical birefringence.
Measuring the nematic order of suspensions of colloidal fd virus by x-ray diffraction and optical birefringence.
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通过 X 射线衍射和光学双折射测量胶体 fd 病毒悬浮液的向列序。
DOI：
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
S. Mochrie
中科院分区：
文献类型：
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作者：
K. Purdy;Z. Dogic;S. Fraden;A. Rühm;L. Lurio;S. Mochrie
用x-射线衍射法测定了半柔性杆状病毒fd悬浮液中α相的取向分布函数与浓度和离子强度的关系。从一个单一的域的FD相的X射线衍射的影响，在低角度的粒子间的相关性，而只有粒子内散射在高角度的贡献。因此，散射强度的角分布仅来自高角度下的单粒子取向分布函数，但它也包括低角度下的空间和取向相关性。对粒子间（结构因子）和粒子内（形状因子）散射的取向分布函数进行了实验测量，以测试粒子间散射中存在的相关性是否影响单粒子取向分布函数的测量。结果发现，这两种类型的散射产生一致的值的顺序参数。还发现，X射线衍射是不敏感的取向分布函数的精确形式，和所测量的角强度分布同样好地描述由两个Onsager的试探函数和高斯。在高离子强度下，与各向同性相共存的α相的序参数S接近长半柔性棒S=0.55的理论预测，但与理论的偏差随着离子强度的降低而增加。的浓度依赖性的顺序参数也更好地同意在高离子强度的理论预测，表明静电相互作用有一个可测量的影响的顺序参数。所示的x射线的顺序参数是成比例的测量的双折射，并确定FD的饱和双折射，使一个简单的，廉价的方式来测量的顺序参数。此外，还对量子点的空间有序性进行了探讨。的结构因子的测量显示了一个单一的大峰，而向列相的刚性棒。
The orientational distribution function of the nematic phase of suspensions of the semiflexible rodlike virus fd is measured by x-ray diffraction as a function of concentration and ionic strength. X-ray diffraction from a single-domain nematic phase of fd is influenced by interparticle correlations at low angle, while only intraparticle scatter contributes at high angle. Consequently, the angular distribution of the scattered intensity arises from only the single-particle orientational distribution function at high angle but it also includes spatial and orientational correlations at low angle. Experimental measurements of the orientational distribution function from both the interparticle (structure factor) and intraparticle (form factor) scattering were made to test whether the correlations present in interparticle scatter influence the measurement of the single-particle orientational distribution function. It was found that the two types of scatter yield consistent values for the nematic order parameter. It was also found that x-ray diffraction is insensitive to the orientational distribution function's precise form, and the measured angular intensity distribution is described equally well by both Onsager's trial function and a Gaussian. At high ionic strength, the order parameter S of the nematic phase coexisting with the isotropic phase approaches theoretical predictions for long semiflexible rods S=0.55, but deviations from theory increase with decreasing ionic strength. The concentration dependence of the nematic order parameter also better agrees with theoretical predictions at high ionic strength indicating that electrostatic interactions have a measurable effect on the nematic order parameter. The x-ray order parameters are shown to be proportional to the measured birefringence, and the saturation birefringence of fd is determined enabling a simple, inexpensive way to measure the order parameter. Additionally, the spatial ordering of nematic fd was probed. Measurements of the nematic structure factor revealed a single large peak in contrast to nematics of rigid rods.
DOI：
10.1103/physreve.61.6872
发表时间：
2000
期刊：
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics
影响因子：
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作者：
Kramer,EM;Herzfeld,J
通讯作者：
Herzfeld,J