We investigate the buckling of a colloidal chain under compression. The compression is induced by laser tweezers holding the colloidal chain on both ends. We observe a buckling transition, but with a key new twist: due to the thermal fluctuations, the chain exhibits thermally excited vibrations that diverge at the buckling transition. Concomitantly, the fluctuation time scales diverge. The figures below show the experimental setup and images (Fig. 1), the recorded buckling (Fig. 2), and the divergence of fluctuations (Fig. 3). We can quantitatively understand and model this thermally excited buckling transition from the elastic buckling of a rod in the presence of stochastic noise. Read more in our paper …
Figure 1: Buckling of a colloidal chain probed by optical tweezers. A schematic of the experiment is shown on the left (a), and microscope images and their reconstructions of the buckling transition under increasing compression in (b) and (c).Fig. 2: Buckling of a colloidal chain: force (a), first-mode amplitude (b), and entropic contribution to the force (c) as a function of compression u. The kink in the force signals analogy with a classical buckling transition. Figure 3: Divergence of fluctuations and time scales. The fluctuations of the first-mode amplitude diverge at the buckling transition (a), and so does the corresponding fluctuation time scale (b). Experimental and simulation data are indicated by grey and blue triangles, respectively, and model predictions by pink curves.
