Raman spectra of hydrated bilayers of 1,2-dilauroyl-sn-glycero-3-phosphocholine (12:0 PC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (14:0 PC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (18:0 PC) were studied in a wide temperature range to characterize the temperature-dependent hydrocarbon chain disorder of the saturated phosphatidylcholines. Temperature dependencies of the Raman line intensities were analyzed for the antisymmetric CH₂ stretching and CC stretching vibrations, which are sensitive to the lipid order. It was found that chain disordering processes occur significantly below the gel-fluid transition. The chain conformational order characterized by the CC stretching line intensity can be well described by a model involving the excitation of the ordered conformational state to the kinked and highly disordered, fluid-like state. A relation between the excitation energy to the disordered state and the enthalpy of the gel-fluid transition is discussed, including also data for other phosphatidylcholines studied before. Temperature behavior of the antisymmetric CH₂ stretching line indicates that non-conformational degrees of freedom are released above ∼ 200 K. Experimental findings concerning the hydrocarbon chain length dependence of the Raman polarizability of antisymmetric CH₂ stretching vibrations and a low-temperature solid-solid phase transition, identified in 12:0 PC at heating, are also discussed in the work.

1,2-二月桂酰-sn-甘油-3-磷酸胆碱（12：0 PC），1,2-二肉豆蔻酰基-sn-甘油-3-磷酸胆碱（14：0 PC）和1,2的水合双层的拉曼光谱-二硬脂酰-sn-甘油-3-磷酸胆碱（18：0 PC）在较宽的温度范围内进行了研究，以表征饱和磷脂酰胆碱的温度依赖性烃链紊乱。分析了对脂质顺序敏感的反对称CH ₂拉伸和CC拉伸振动对拉曼谱线强度的温度依赖性。已经发现，链紊乱过程明显发生在凝胶-流体转变以下。CC表征的链构象顺序拉伸线强度可以通过一个模型来很好地描述，该模型涉及将有序构象态激发为扭结和高度无序的类流体态。讨论了激发能到无序态与凝胶-流体转变焓之间的关系，还包括之前研究的其他磷脂酰胆碱的数据。反对称CH ₂拉伸线的温度行为表明，非构象自由度在〜200 K以上释放。关于反对称CH ₂拉伸振动的拉曼极化率和低温固-体的烃链长度依赖性的实验结果在工作中还讨论了在12：0 PC加热时识别的相变。