Size and temperature dependency on structure, heat capacity and phonon density of state for colloidal silver nanoparticle in 1-Ethyl-3-methylimidazolium Hexafluorophosphate ionic liquid

Abstract

Abstract Phonon detector can be designed by using colloidal silver nanoparticle (Ag NP) in presence of 1-Ethyl-3-methylimidazolium Hexafluorophosphate [EMim][PF6] ionic liquid (IL) via computational technique as the first time for many and high performance biosensors applications. Density functional theory as a quantum chemistry calculation method has been used to get the potential interaction between silver metal and ionic solvent. Molecular dynamics simulation shows that in small sizes of colloidal Ag NP in [EMim][PF6], electrical effect of IL makes one main phonon peak and in big size of colloidal Ag NP, splitting of phonon density occurs with two peaks due to the lower electrical field of IL with the surface metal. There is non-monotonic behavior for phonon mean collision time in terms of colloidal Ag NP size in IL; however, phonon mean collision time for Ag NP in gas phase decreases monotonically as the Ag NP size increases. In big size of colloidal Ag NP in IL the distance frequency of main phonon peak is closer than those in gas phase. The size of colloidal Ag NP does not have a significant effect on charge separation; cation head group and anion coincide in the vicinity of the NP for the all sizes of Ag NP. Metal dipole moment due to electrical field of IL has an effect around metal surface, reducing heat capacity of colloidal silver nanoparticle in comparison with the gas phase of Ag NP and finally heat capacity of colloidal silver nanoparticle approaches to the gas phase as the size of Ag NP increases. MD simulation shows that there is non-monotonic behavior for stabilization energy as a function of Ag NPs sizes. Our result regarding phonon DOS for Ag NP and Ag bulk are in agreement with the available experimental data.