Time and space-resolved study of a laser-produced SiO plasma

IBER2015, Aveiro, Portugal, 6th to 9th September of 2015; http://iber2015.web.ua.pt/Time and space-resolved study of a laser-produced SiO plasma L. Diaz1 and J. J. Camacho2 1Instituto de Estructura de la Materia, CFMAC, CSIC, Serrano 121, 28006 Madrid, Spain 2Dpto. Química-Física Aplicada, Fac. Ciencias. UAM, Cantoblanco 28049, Madrid Spain E-mail: luis.diaz@csic.es Nanosecond laser-sample interaction involves complex processes of heating, vaporization, ejection of ions, electrons, atoms and molecules, shock waves, plasma initiation, expansion and recombination. Analysis of laser-produced plasmas (LPPs) can be a very challenging task considering its transient nature as well as large variations in plasma properties with space and time. There are numerous diagnostic techniques that can be employed to study the characteristics of laser ablation such as shadowgraphy, interferometry, self-emission imaging using fast gated cameras, optical emission spectroscopy (OES), Langmuir probe, Faraday cup, etc. Each plasma diagnostic tool has its own advantages and limitations. In this work, we present a spatial and temporal analysis of the LPP generated on silicon monoxide SiO. Time-resolved two-dimensional (2D) OES is used to study the expanded distribution of different species ejected during CO2 laser ablation. The formed plasma was found to be strongly ionized yielding Si+, O+, Si2+, O2+, Si3+, O3+ species, rich in neutral silicon and oxygen atoms and very weak molecular bands of SiO [1]. Typical 2D spectral images (transversely excited atmospheric CO2 laser fluence = 72 J/cm2 and Pair = 0.01 Pa) recorded at 0.1 and 0.5 ¿s delays for a fixed gate width time of 0.1 ¿s are given in the above figures. The results show a faster decay of Si3+, O3+, O2+, and Si2+ than of O+, Si+ and Si. The Stark broadening of isolated Si+ lines was employed for deducing the electron density during the plasma expansion. The relative intensities of some Si2+ lines were used to calculate the time evolution of the plasma temperature. By tracking the maximum intensity displacement for some species, its corresponding velocities were deduced. Acknowledgments: We gratefully acknowledge the support received in part by the DGICYT (Spain) project MICINN: CTQ2013-43086 for this research. [1] L. Diaz, J.J. Camacho, J.P. Cid, M. Martin, J.M.L. Poyato, Appl. Phys. A, 117, 125-129 (2014).We gratefully acknowledge the support received in part by the DGICYT (Spain) project MICINN: CTQ2013-43086 for this research.Peer Reviewe