Harada Takunori, Manabe Kazusa
Department of Integrated Science and Technology, Faculty of Science and Technology, Oita University, Dannoharu, 700, Oita City 870-1192, Japan.
Rev Sci Instrum. 2020 Dec 1;91(12):125108. doi: 10.1063/5.0029948.
A new dual-polarization-modulated comprehensive chiroptical spectrophotometer (D-CCS) was successfully developed for recording artifact-free chiroptical circular dichroism (CD) and circularly polarized luminescence (CPL) spectra of optically anisotropic samples on the basis of the Stokes-Mueller matrix approach. The D-CCS includes an additional second photoelastic modulator (PEM) set in front of the sample and a second PEM controller being driven independently of the first PEM driver, which are essential for obtaining artifact-free chiroptical signals of optically anisotropic samples containing non-chiral signals, i.e., linear birefringence, linear dichroism, and linearly polarized luminescence. The theory and implementation of the method are described, and examples of its application to CD and CPL samples with macroscopic anisotropies are provided. An important advantage of the developed D-CCS is that it reduces the essential step of sample rotation in the plane, including the gravitational axis, to obtain artifact-free CD signals. Consequently, this dual-polarization method shortens the time required to obtain artifact-free CD signals by half and could be very effective for samples, such as high fluidity samples, gels, liquid crystals, and supramolecules in solution, for which artifact-free chiroptical signals are difficult to obtain using conventional methods.
基于斯托克斯 - 米勒矩阵方法，成功开发了一种新型双偏振调制综合手性光分光光度计（D - CCS），用于记录光学各向异性样品的无伪影手性光圆二色性（CD）和圆偏振发光（CPL）光谱。D - CCS包括一个设置在样品前方的额外的第二光弹调制器（PEM）和一个独立于第一PEM驱动器驱动的第二PEM控制器，这对于获得包含非手性信号（即线性双折射、线性二色性和线偏振发光）的光学各向异性样品的无伪影手性光信号至关重要。描述了该方法的理论和实现方式，并提供了其应用于具有宏观各向异性的CD和CPL样品的示例。所开发的D - CCS的一个重要优点是，它减少了在包括重力轴在内的平面内旋转样品以获得无伪影CD信号这一必要步骤。因此，这种双偏振方法将获得无伪影CD信号所需的时间缩短了一半，对于诸如高流动性样品、凝胶、液晶和溶液中的超分子等难以使用传统方法获得无伪影手性光信号的样品可能非常有效。
