Formation and Growth of Silver Nanocubes upon Nanosecond Pulsed Laser Irradiation: Effects of Laser Intensity and Irradiation Time

Umair Yaqub Qazi,Hiroshi Fukumura,Zameer Shervani,Shinji Kajimoto,Rahat Javaid

doi:10.4236/anp.2017.64013

Abstract

Silver nanoparticles (AgNPs) were fabricated by repetitive irradiation of near ultraviolet (UV) nanosecond laser pulses (355 nm, 5 ns) in an aqueous solution of silver nitrate in the absence of stabilizing agents. A broad absorption peak was observed in the visible region showing the formation of a variety of AgNPs in the solution. Among the variety of products, it was found that silver nanocubes (AgNCs) grew in size with longer laser irradiation time. The size of AgNCs also increased with higher laser intensity. The average size of AgNCs, investigated by a scanning electron microscope (SEM) was in the range of 75 - 200 nm. The number of reduced atoms in AgNCs as a function of laser intensity showed that the AgNCs are apparently produced by a four photon process, implying that the formation of dimer silver atoms is essential for the formation.

Highlights

In last few decades, fabrication of nanomaterials (NMs) has been of great interest because of their unique physicochemical properties which differentiate them from those of the corresponding “bulk” materials [1] [2]
Prepared AgNO3 solution did not show absorption at 355 nor 405 nm; when the sample solution was irradiated with ns laser pulses, a new broad absorption peak was observed at 405 nm, indicating the formation of AgNPs which has the surface plasmon resonance (SPR) band around 400 nm
The repetitive irradiation of UV pulses causes the excitation of silver nanoparticles, which can lead to electron ejection from nanoparticles and further formation and aggregation/growth of nanoparticles as well as the laser ablation of nanoparticles

Summary

Introduction

Fabrication of nanomaterials (NMs) has been of great interest because of their unique physicochemical properties which differentiate them from those of the corresponding “bulk” materials [1] [2]. A method using pulsed laser irradiation might be similar to radiolysis as photon works as a reducing agent, which provides electrons, and stable NPs are synthesized in an aqueous solution of metal salts containing suitable dispersing agents [17] [18] [19]. This method helps us to generate metal NPs with narrow size distribution and completely free from extra reducing chemicals.

Experimental

Results and Discussion

Conclusion