Alexander C. Woods

We present results including measurement and analysis of titanium monoxide. Pulsed, nanosecond Nd:YAG laser radiation is used in a typical laser-induced breakdown spectroscopy arrangement to record the spectra. This scheme provides experiments analogous to pulsed laser deposition tactics and allows for time-resolved spectroscopic analysis. The computed spectra are generated from a new, accurate line-strength file that allows us to accurately predict $\gamma$ ($A^3\mathrm{\Phi }\to X^3\mathrm{\Delta }$) and ${\gamma }^{\prime }$ ($B^3\mathrm{\Pi }\to X^3\mathrm{\Delta }$) spectral signatures. We infer temperature on the order of $3600\pm 700\mathrm{K}$ and $4200\pm 800\mathrm{K}$ at time delays of 52 and 72 μs, respectively. Current interest in this work includes titania (${\mathrm{TiO}}_2$) nanoparticle generation for thin film applications.

We present analysis of superposition spectra following laser-induced breakdown (LIB) of methane. Both hydrogen-beta and hydrogen-gamma lines contain discernible contributions from diatomic carbon emissions for time delays of 1 to 2 μs from pulsed, 8 ns, infrared Nd:YAG laser radiation LIB. Analysis of the atomic lines and molecular ${\mathrm{C}}_2$ spectra reveal electron and molecular excitation temperatures of typically 13,000 and 5000 K, respectively.

This work investigates Titanium Monoxide (TiO) in ablation-plasma by employing laser-induced breakdown spectroscopy (LIBS) with 1 to 10 TW/cm² irradiance, pulsed, 13 nanosecond, Q-switched Nd:YAG laser radiation at the fundamental wavelength of 1064 nm. The analysis of TiO is based on our first accurate determination of transition line strengths for selected TiO A-X, B-X, and E-X transitions, particularly TiO A-X γ and B-X γ′ bands. Electric dipole line strengths for the $A^3{\mathrm{\Phi -X}}^3\delta$ and $B^3{\mathrm{\Pi -X}}^3\delta$ bands of TiO are computed. The molecular TiO spectra are observed subsequent to laser-induced breakdown (LIB). We discuss analysis of diatomic molecular spectra that may occur simultaneously with spectra originating from atomic species. Gated detection is applied to investigate the development in time of the emission spectra following LIB. Collected emission spectra allow one to infer micro-plasma parameters such as temperature and electron density. Insight into the state of the micro-plasma is gained by comparing measurements with predictions of atomic and molecular spectra. Nonlinear fitting of recorded and computed diatomic spectra provides the basis for molecular diagnostics, while atomic species may overlap and are simultaneously identified. Molecular diagnostic approaches similar to TiO have been performed for diatomic molecules such as AlO, C₂, CN, CH, N₂, NH, NO and OH.