Role of laser pre-pulse wavelength and inter-pulse delay on signal enhancement in collinear double-pulse laser-induced breakdown spectroscopy Diwakar, P.K., E-mail: pdiwakar@purdue.edu; Harilal, S. S.; Freeman, J. R.; Hassanein, A. 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; EMISSION; EXCITATION; PEAKS; PLASMA DIAGNOSTICS; PULSES; SENSITIVITY; SIGNALS; SPECTROSCOPY; TEMPERATURE MEASUREMENT; WAVELENGTHS Dual-pulse (DP) laser-induced breakdown spectroscopy (LIBS) provides significant improvement in signal intensity as compared to conventional single-pulse LIBS. We investigated collinear DPLIBS experimental performance using various laser wavelength combinations employing 1064 nm, 532 nm, and 266 nm Nd:YAG lasers. In particular, the role of the pre-pulse laser wavelength, inter-pulse delay times, and energies of the reheating pulses on LIBS sensitivity improvements is studied. Wavelengths of 1064 nm, 532 nm, and 266 nm pulses were used for generating pre-pulse plasma while 1064 nm pulse was used for reheating the pre-formed plasma generated by the pre-pulse. Significant emission intensity enhancement is noticed for all reheated plasma regardless of the pre-pulse excitation beam wavelength compared to single pulse LIBS. A dual peak in signal enhancement was observed for different inter-pulse delays, especially for 1064:1064 nm combinations, which is explained based on temperature measurement and shockwave expansion phenomenon. Our results also show that 266 nm:1064 nm combination provided maximum absolute signal intensity as compared to 1064 nm:1064 nm or 532 nm:1064 nm. - Highlights: • Role of pre-pulse wavelength and inter-pulse delay on LIBS sensitivity was studied. • For NIR:NIR combination, dual peaks in signal enhancement were observed. • UV:NIR combination resulted in maximum absolute signal intensity. • Persistence of neutral species was increased for double pulse. Available from http://dx.doi.org/10.1016/j.sab.2013.05.015 Netherlands 2013-09-01 English Journal Article Conference Journal Name: Spectrochimica Acta. Part B, Atomic Spectroscopy; Journal Volume: 87; Conference: LIBS 2012: 7. international conference on laser induced breakdown spectroscopy, Luxor (Egypt), 29 Sep - 4 Oct 2012; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA) Medium: X; Size: page(s) 65-73 https://doi.org/10.1016/J.SAB.2013.05.015 PII: S0584-8547(13)00118-3 [] 87 Journal ID: ISSN 0584-8547; CODEN: SAASBH; Other: PII: S0584-8547(13)00118-3; TRN: NL14S6730042990 NLN 2015-05-14 22336696