Utilizing a combination of time-resolved Infrared (IR) spectroscopies, we are able to probe the effects of a small biological molecule (cholesterol) on the dynamics of lipid membranes from picoseconds to milliseconds. By monitoring the ultrafast dynamics of the system with multi-dimensional IR spectroscopy, we are able to resolve the influence cholesterol has on the electric field fluctuations inside the membrane. We use temperature-jump (T-jump) spectroscopy to extend our experimentally-observable time window beyond the vibrational lifetime of our probe and find that the presence of cholesterol introduces significant inhomogeneity into the relaxation rates of the system. This approach provides new insight into the interaction between cholesterol and lipids, while also demonstrating the utility of this combined IR spectroscopic toolbox for studying multiscale dynamics.

利用时间分辨红外（IR）光谱技术的组合，我们能够探测小生物分子（胆固醇）对脂膜动力学的影响（从皮秒到毫秒）。通过使用多维红外光谱监测系统的超快动力学，我们能够解决胆固醇对膜内部电场波动的影响。我们使用温度跃变（T-jump）光谱技术将我们在实验上可观察到的时间范围扩展到探针的振动寿命之外，并且发现胆固醇的存在会导致系统的弛豫率显着不均匀。这种方法为胆固醇和脂质之间的相互作用提供了新的见解，