Figure 1

Experimental setups. (a) Schematic of the low-coherence dynamic light scattering (LC-DLS) apparatus. A low-coherence light source \({\lambda }_{\text{DLS}}=680\) nm (Superlum, Ireland), coherence length approximately \(20\,\mu m\), is collimated and focused on the edge of the sample cell. The backscattered light is collected at an angle of \(\theta \approx {170}^{\circ }\) with momentum transfer \({q}_{{\rm{DLS}}}\simeq 0.025\) nm⁻¹ and analyzed by a digital correlator. An upper goniometer can be employed to rotate the sample and measure the ensemble averaged scattered intensity also for dynamically arrested samples. (b) Schematic of the diffusing wave spectroscopy (DWS) setup. A green (\({\lambda }_{\text{DWS}}\,=\,532\) nm) laser light source is split into two beams. Two-cell Echo-DWS is implemented by scrambling the beam with a rotating ground glass diffuser⁶³. The light is subsequently collimated to illuminate the sample with an approximately \(8\) mm diameter beam. The multiply scattered light is detected by a photon detector in transmission. The second beam is acting at a local oscillator with adjustable intensity. A shutter allows for selection of homodyne or heterodyne configuration⁴².