Project Summary

Research team

Publications

    

PROJECT SUMMARY

    

    

The project is focused on study and development of combined technologies for creation of Surface Enhanced Raman Spectroscopy (SERS) substrates towards the analysis and detection of materials as nitrates and pesticides. The objects of investigation are Ag/ZnO nanostructures with plasmonic properties, which will be applied to high resolution analysis (SERS) and the efforts are forwarded to human health by food and water safety. The activities of this interdisciplinary project are related to fundamental scientific research by detail description of the interaction of nanostructured composite objects with electromagnetic field, their optical properties, as well as determination of mechanisms and conditions for their effective modification. The efficient application of Raman spectroscopy for precise determination of the chemical composition and structure analysis of the investigated objects became popular with the development of Surface Enhanced Raman Spectroscopy (SERS) methods, where the Raman signal enhancement could be improved as a result of local enhancement of the electromagnetic field in the vicinity of a structured surface, due to the excitation of local and surface plasmons. The charge transfer contribution to SERS effect, enhanced by surface plasmon resonance in composite nanostructures of Ag/ZnO is of particular interest for this study. The main direction of investigations is the design of appropriate structures by pulsed laser deposition (PLD) of ZnO thin films, ion implantation of Ag+ ions in ZnO matrix and surface modification of composite nanostructures by laser annealing. The atomic concentration of silver after ion implantation may reach a value that is much higher than the limit of metal solubility in oxide semiconductors, such as ZnO. The effective accumulation of silver atoms in ZnO at high-dose implantation with low energy leads to nucleation and growth of silver nanoparticles near the surface of irradiated material. By means of pulsed laser annealing of ion implanted Ag nanoparticles in the ZnO films, it is possible to affect the surface areas of the processed composite material using very rapid thermal cycles, in conditions generally far from the thermodynamic equilibrium. As a result, the activation of complex mechanisms takes place and the laser-induced modification of the composites will become an appealing area of research because of its potential use in tailoring material properties for SERS applications. The correlation between the fabrication, characterization and SERS performance of Ag/ZnO nanostructures will be established.

   

    

    

RESEARCH TEAM

    

Assoc. Prof. Mihaela Koleva, PhD (Team leader)

  

Prof. Nikolay Nedyalkov, DSc

  

Assis. prof. Rumen Nikov, PhD

  

Assis. prof. Rosen Nikov, PhD

    

    

    

 
 
 
 

    

    

PUBLICATIONS

1. M.E. Koleva, N.N. Nedyalkov, D. Karashanova, G.B. Atanasova, A.L. Stepanov,

   Modification of plasmon resonance properties of noble metal nanoparticles inside the glass matrices,

   Applied Surface Science, 475, 2019, 974-981.

2. M.E. Koleva, N.N. Nedyalkov, V.I. Nuzhdin, V.F. Valeev, Y.N. Osin, A.L. Stepanov,

   Synthesis and characterization of surface embedded silver nanoparticles in ZnO matrix,

   Proceedings of SPIE, 11047, 2019, 110470I.

3. M.E. Koleva, N.N. Nedyalkov, Ru. Nikov, Ro .Nikov, G. Atanasova, D. Karashanova, V.I. Nuzhdin, V.F. Valeev, A.M. Rogov A.L. Stepanov,

   Fabrication of Ag/ZnO nanostructures for SERS applications,

   Applied Surface Science, 508, 2020, 145227.

4. M.E. Koleva, N.N. Nedyalkov, Ru. Nikov, Ro. Nikov, V.I. Nuzhdin, V.F. Valeev, A.M. Rogov, A.L. Stepanov,

   Hybrid Ag/ZnO nanostructures for SERS detection of ammonium nitrate,

   J. Phys. Conf. Series, accepted for publication, 2020.