R. K. Swarnkar

Dumbbell shaped nickel nanocrystals synthesized by a laser induced fragmentation method

Dumbbell shaped nickel nanoparticles have been synthesized for the first time by laser induced fragmentation of bulk nickel powder in aqueous sodium dodecyl sulfate. The focused output of the third harmonic from a nanosecond pulsed Nd:YAG laser operating at 35 mJ/pulse energy was used for the photo-fragmentation of micron size particles suspended in 50 mM aqueous medium. Nickel anisotropic nanocrystals have been grown by recrystallisation of nickel particles due to laser plasma generated in sodium dodecyl sulfate solution. The Vibrating Sample Magnetometer measurements of dumbbell shaped nickel nanostructure show their good ferromagnetic nature. The mechanism of the synthesis of nanostructure through melting and fragmentation has been also discussed.

Synthesis of Copper/Copper-Oxide Nanoparticles: Optical and Structural Characterizations

In the present study, we have synthesized copper/copper‐oxide nanoparticles by laser ablation of copper metal in aqueous solution of sodium dodecyl sulfate. The focused output of 1064 nm wavelength of pulsed Nd:YAG laser is used for ablation. The synthesized nanoparticles are characterized by UV‐visible absorption, X‐ray diffraction, transmission electron microscopy and Raman spectroscopy techniques. The synthesis of copper/copper oxide nanoparticles are confirmed by XRD and Raman studies. The possible mechanism of nanoparticle formation is also discussed.

Cadmium Oxide Nanostructures in Water; Synthesis, Characterizations & Optical Properties

Cadmium oxide nanoparticles are synthesized by pulsed laser ablation of cadmium metal in double distilled water, which are found stable for 24 hours. The sample is characterized by using UV‐VIS absorption, scanning electron microscopy, thermo gravimetric analysis, differential thermal analysis, X‐ray diffraction and fourier transform infrared techniques. XRD pattern shows that as synthesized nanopowder has maximum amount of the Cadmium hydroxide rather than its oxide, which converts into Cadmium oxide after annealing at 350° C.

Surface Enhanced Raman Spectroscopy of Volatile Organic molecules on the surface of Zinc Nanoparticles Produced by Laser Ablation

Surface enhanced Raman spectroscopy have provided potential tool for the detection of organic/biological molecules within the cell of living organism. This technique is suitable for in vivo as well as in vitro detection upto single molecular level. In the present work we have studied SERS activity of zinc nanoparticles on CCl4 and CHCl3 molecules. Colloidal solution of zinc nanoparticles was found as a suitable substrate for Raman signal enhancement. The applied technique may be useful for the sensing of organic/biological molecules as a trace in solid as well as in liquid media.

SERS Study of Alizarin Red Dye on Colloidal Silver Nanoparticles

The present paper deals with surface enhanced Raman scattering (SERS) study of an organic dye Alizarin Red on colloidal silver nanoparticles. The colloidal solution of nanoparticles is synthesized by pulsed laser ablation of silver rod in pure deionized water using focused out put of 1064nm wavelength of Nd:YAG laser having 35mJ/ pulse energy. Sodium chloride is used as aggregating agents. It is observed that SERS enhancement factor varies strongly depending on concentration of used aggregating agent (especially on the concentration of Cl- ions). These changes in SERS efficiency of colloid are reflected through changes on the absorption spectra. The possible mechanism of SERS is also discussed.

Raman Signal Enhancement Based Chemical Sensing of Volatile Organic Compounds

Surface enhanced Raman scattering based optical sensing (SERS‐OS) is one of the most powerful techniques for the sensitive and selective detection of low concentration analytes. Mostly, metallic nanoparticles, such as Ag, Au and Cu, are used as substrate materials in this technique. Present work is concerned with the possibility of utilization of colloidal zinc nanoparticles, produced by pulsed laser ablation method, as substrate material in SERS‐OS.