where 𝐷 is the diffusion coefficient and 𝜏 is the diffusion time. 𝐷 is estimated by using the Stokes-Einstein equation (𝐷 = 𝑘 S 𝑇 6𝜋𝜂𝑟 ⁄ ). In this, 𝑑 and 𝜏 correspond to the Δ𝑟 and 𝑡 VM++W%WMX , respectively. 𝐷 in toluene is estimated to be 7.8 × 10 -10 m 2 /s at 298 K. Thus, 𝑡 VM++W%WMX = 2.1 ps is obtained to be comparable to