DOI: 10.1063/1.4977893

Authors
Li, N. ; Li, Y. D. ; Lu, Y. ; Zheng, R.

Keywords

BULK AQUEOUS-SOLUTIONS; SINGLE-PULSE; ELEMENTAL ANALYSIS; OPTICAL-BREAKDOWN; OCEANIC PRESSURES; PLASMA FORMATION; WATER; LIQUIDS; NANOSECOND; PARAMETERS

Abstract

Axial focusing arrangement effects on collinear dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) in a bulk solution were investigated by spectra and fast images. By properly defocusing the second laser pulse beyond the first laser formed bubble (LFB), brighter and larger plasmas could be produced due to higher breakdown efficiency and higher expansion efficiency. It is attributed to a distinct mechanism of underwater DP-LIBS that the plasma mostly forms at the bubble-water interface and then expands into the gaseous LFB. The results show that optimization of the axial focusing arrangement in underwater collinear DP-LIBS enables significant emission enhancements with relatively low laser energies. Published by AIP Publishing.

DOI: 10.1063/1.4991824

Authors
Armstrong, M. R. ; Azer, M. ; Crowhurst, J. C. ; Curreli, D. ; Finko, M. S. ; Isselhardt, B. H. ; Koroglu, B. ; Radousky, H. B. ; Rose, T. P. ; Savina, M. R. ; Siekhaus, W. J. ; Zaug, J. M.

Keywords

INDUCED BREAKDOWN SPECTROSCOPY; MOLECULAR ISOTOPIC SPECTROMETRY; URANIUM MONOXIDE; INDUCED PLASMAS; SPECTRA; UO; COMPUTATION; STATES; ORE

Abstract

We have measured vibronic emission spectra of an oxide of uranium formed after laser ablation of the metal in gaseous oxygen. Specifically, we have measured the time-dependent relative intensity of a band located at approximately 593.6 nm in O-16(2). This band grew in intensity relative to neighboring atomic features as a function time in an oxygen environment but was relatively invariant with time in argon. In addition, we have measured the spectral shift of this band in an O-18(2) atmosphere. Based on this shift, and by comparison with earlier results obtained from free-jet expansion and laser excitation, we can confirm that the oxide in question is UO, consistent with recent reports based on laser ablation in O-16(2) only. Published by AIP Publishing.