Fig. 4

Diffraction ring patterns observed for Ramshir (a, d), Rag-e-Sefid (b, e), and Ahwaz-20 (c, f) crude oil/toluene samples irradiated with \(405 nm\) and \(532 nm\) laser beams, respectively. The samples were prepared at the highest concentration of \(1\text{ mL}/\text{L}\).