S. C. Singh

Laser Induced Molecular Spectroscopy of Zn2 Molecule

Laser produced spectra of zinc molecule have been recorded in the region of 540–670 nm using second harmonics of Nd: YAG laser, computer—controlled TRIAX 320 M monochromator with a reciprocal linear dispersion 2.64 nm/mm fitted with ICCD detector. The spectrum consists of 35 bands, which are classified into D (1∏u)→A(3∏g) and C (1Σu+)→A(3∏g) systems. We have recorded the florescence spectrum of zinc dimer by pumping and probing with the same laser, which proves that produced molecules are stable for more than 0.1 seconds.

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.

Potential Energy Surface Calculations of Alanine Dipeptide using BVWN Density Functional Approach and 6-311G Basis Set

This work is devoted to a study of the conformational properties of alanine dipeptide. We have studied potential energy surfaces of alanine dipeptide molecule using density functional theoretical approach with 6-311G basis set. For this purpose potential energies of this molecule are calculated as a function of Ramachandran angles φ and ψ, which are important factors for the characterizations of polypeptide chains. These degrees of freedoms φ and ψ are important for the characterization of protein folding systems. Stable conformations, energy barriers and reaction coordinates of this important dipeptide molecule are calculated. Energy required for the transition of one conformation into other are also discussed.

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.