UV–vis absorption of silver TNPs prepared here has three characteristic absorption bands at 334 nm, 410 nm and 558 nm respectively (Fig. 1A). Compared the spectrum with reported reference, we can attribute the 558-nm band to the in plane dipole plasmon resonance, the 334-nm band to the out of plane quadrupole resonance of silver nanoplates. The in plane quadrupole resonance and out-of-plane dipole resonance band are sufficiently weak and overlap together that it is barely discernible as a shoulder of 558-nm band at 410 nm [24,26,28,51]. After addition of iodide in silver TNPs solution, the in-plane dipole plasmon resonance peak of silver TNPs at 558 nm decreased and a new peak at 416 nm increased with the increasing of iodide, the color of nanoparticles suspension changed from blue to yellow (Fig. 1B). We deduced that the absorption spectral transformation of the silver TNPs solution is a manifestation of morphological transformation occurred to the silver TNPs.