Enhanced nonlinear optical and optical limiting responses of 7-diethylamino-4-methyl coumarin functionalized with silver nanoparticles: A combined experimental and DFT study

The present study accounts for the enhanced nonlinear optical and optical limiting activity of 7-diethylamino-4-methyl coumarin (7DMC) after the addition of silver nanoparticles. The theoretical calculations were done in three different solvents water, methanol, and dimethyl formamide (DMF), and on the basis of the energy gap, DMF was selected as the most suitable solvent. Further, the liquid samples were prepared in DMF. The natural bond orbitals show the active participation of the lone pairs of electrons of 2O and 35Ag as donor and acceptor moieties respectively. The values of first-order hyperpolarizability of the 7DMC+Ag₃ combination were raised to 2002.71 × 10⁻³⁰ esu, 778.72 × 10⁻³⁰ esu, and 677.12 × 10⁻³⁰ esu in water, methanol, and DMF. The valley-like structure in the Z-Scan spectra indicated the occurrence of reverse saturable absorption in the prepared samples. The optical limiting threshold of the 7DMC+AgNps was decreased from that of the probe 7DMC and AgNps indicating the early attenuation of the optical limiting nature of the combination. Thus, the overall results validated the enhanced optical nonlinearity of the combination. Moreover, it can be stated that the proposed nanoparticles combination 7DMC+AgNps has potential candidature to be used for the fabrication of laser safety devices and eye aids.