Light-induced phase transitions of colloidal monolayers with crystalline order
Light-induced phase transitions of colloidal monolayers with crystalline order
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DOI：
10.1039/c3sm50945a
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发表时间：
2013-09
期刊：
影响因子：
3.4
通讯作者：
L. Zaidouny;T. Bohlein;R. Roth;C. Bechinger
中科院分区：
文献类型：
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作者：
L. Zaidouny;T. Bohlein;R. Roth;C. Bechinger
实验研究了一维周期光场作用下电荷稳定的二维胶体晶体的相行为。这样的光场是由扫描的光学线镊子创建的，其允许周期性的变化而无需光学重新排列。为了实现相对于晶格常数的宽范围的线间距，我们使用在溴苯中的二氧化硅颗粒的悬浮液。这种胶体系统具有约4.6 μm的德拜屏蔽长度，这导致形成晶格常数高达20 μm的晶体。由于溴苯的折射率大于胶体的折射率，因此光学梯度力导致在强度最小的区域处的颗粒的吸引。根据光学势的深度和周期性，我们观察到光诱导的组装成三角形，菱形和正方形的胶体相。
We experimentally study the phase behavior of a charge-stabilized two-dimensional colloidal crystal which is subjected to a one-dimensional periodic light field. Such light fields are created by a scanned optical line tweezer which allows the variation of the periodicity without optical realignments. In order to realize a wide range of line spacings relative to the lattice constant, we use a suspension of silica particles in bromobenzene. This colloidal system has a Debye screening length of about 4.6 μm which results in the formation of crystals with lattice constants up to 20 μm. Because the refractive index of bromobenzene is larger than that of the colloids, optical gradient forces lead to the attraction of particles at regions where the intensity is smallest. Depending on the depth and periodicity of the optical potential, we observe the light-induced assembly of colloids into triangular, rhombic and square phases.