Discipline: Chemistry and Chemical Sciences
Caleb Gumbs - Alabama State University
Co-Author(s): Cleon Barnett and Komal Vig, Alabama State University, Montgomery, AL
Laser Induced Breakdown Spectroscopy (LIBS) is a type of atomic emission spectroscopy that is able to analyze the elemental composition of a sample by using laser pulses to create a plasma that is analyzed by a spectrometer. Recent advances in the field of LIBS have shown that the addition of an aqueous nanoparticle solution increased performance through enhancement of emission. This technique has been termed Nanoparticle Enhanced LIBS. In theory, among 266 nm, 532 nm and 1064 nm, 1064 nm should be the most favorable for nanoparticle enhanced LIBS. In this project, through a series of experiments, we explore the influence of wavelength and energy on LIBS emission as well as the possibility of an energy threshold for attainment of emission enhancements. To begin experimentation, 2 μL drops of an aqueous silver nanoparticle solution at concentrations: 0.003 μg/μL, 0.0015 μg/μL and 0.000375 μg/μL were deposited onto gold film. The laser settings were adjusted for the various energies used. Once dried, the gold film was irradiated with an Nd:YAG laser at wavelengths: 266 nm, 532 nm and 1064 nm. The replicates of the Au control and Ag-Np covered Au film at all concentrations and wavelengths were analyzed for a gold line at 267.6 nm (AU I), then averaged and graphed. After using 15 mJ and 20 mJ of energy to irradiate the samples, the results suggest that the addition of the silver nanoparticle solution deteriorated rather than enhanced the intensity of the gold signal. For every wavelength, maximum reduction in gold emission intensity was observed when the concentration of silver nanoparticles was the highest. However, after using 30 mJ and 60 mJ of energy, the intensity of the emissions was higher for the Ag-Np covered Au film. At higher energies to be analyzed, the intensity of the Ag-Np covered film is expected to be much higher than the Au control. The evidence points to the fact that there are definitely optimal conditions to achieve nanoparticle enhanced LIBS. If the concentration is too high and the energy is too low, performance is reduced rather than improved. The results for the 30 mJ and 60 mJ lead us to believe that increasing the energy will help us achieve higher intensity, even at 532 nm. Future studies will aim to find the optimal energy for enhanced Ag-Np Au film emissions.
Funder Acknowledgement(s): This work was supported by US Dept. of Education, The Minority Science and Engineering Improvement Program (MSEIP) (P120A150008) to Dr. Komal Vig (PD) and by NSFCREST (HRD-1241701) to Dr. Shree S. Singh (PI).
Faculty Advisor: Cleon Barnett, firstname.lastname@example.org
Role: I was responsible for much independent work such as: preparing samples, performing laser induced breakdown spectroscopy (LIBS) experiments in various configurations as well as converting and analyzing data. All activities with the exception running the Neodymium Yttrium Aluminum Garnet (Nd:YAG) lasers have been done independently.