Christopher Ball - Alabama State University
Laser Induced Breakdown Spectroscopy (LIBS) is a technique that uses a focused laser beam to breakdown a sample and create an atomic emission indicative of the elemental composition of the sample. There are several key factors that influence the intensity, reproducibility, and ultimately the analytical performance of the LIBS system. There are many influences to the observed in atomic emission which include: surface reflectivity, laser pulse length, and focusing conditions. To better understand the importance of surface reflectivity in single shot LIBS, we have used three wavelengths of the Nd:YAG laser to create plasma on a gold thin film. The gold thin film is 100 nm thick and attached to a silicon wafer using 5 nm of titanium. A series of experiments were conducted at three irradiation wavelengths (266 nm, 532 nm, and 1064 nm) to determine the influence that irradiation wavelength has on the emission emerging from a gold thin film. The reflectance of gold at 266 nm is .384, .807 at 532 nm, and .991 at 1064 nm. Many of the previous studies that focus on the influence of excitation wavelength involve metals over which the reflectivity does change significantly. Results from LIBS analysis using three harmonics of a Nd:YAG, namely 266 nm, 532 nm and 1064 nm is presented. In addition, we present plasma density and excitation temperature estimations based on spectroscopic data.
Funder Acknowledgement(s): NSF; MSEIP; Alabama State University
Faculty Advisor: Cleon Barnett, Llucas@alasu.edu
Role: I performed the experiment and took the data samples. Most of the work was overseen by my mentor to ensure proper validation of work and safety in handling of equipment.