Abstract：With the hope of applying laser induced breakdown spectroscopy (LIBS) to the ocean applications, the laser energy at 532 and 1 064 nm wavelength with 3 and 40 mj respectively was used, which was near their breakdown threshold. Extensive experimental investigations of LIBS from CaCl2 water solution were carried out in this paper using different laser wavelengths of 532 and 1 064 nm. The obtained results show that compared with the 532 nm laser, the 1 064 nm laser can induce the plasma in water with higher emission intensity and longer lifetime, while the reproducibility of LIBS signal under 1 064 nm laser is poorer. On the other hand, due to the different attenuation ratios of 532 and 1 064 nm laser energies in water, the LIBS signal of 1 064 nm laser decreases a lot within the transmission distance range 2～5 cm, while LIBS signal of 532 nm remains the same, because that the wavelength of 532 nm lies in the "transmission window" of the water solution. This study will provide valuable design considerations for the development of LIBS-sea system in near future.
[1] Brewer P G, Malby G, Pasteris J D, et al. Deep-Sea Research I, 2004, 51: 739. [2] Pasteris J D, Wopenka B, Freeman J J, et al. Applied Spectroscopy, 2004, 58: 195A. [3] Battaglia T M, Dunn E E, Lilley M D, et al. Analyst, 2004, 129: 602. [4] Seyfried W E, Pester N J, Ding K, et al. Geochimica et Cosmochimica Acta, 2011, 75(6): 1574. [5] Michel A P M, Chave A D. Applied Optics, 2008, 47(31): G131. [6] Demina L L, Holm N G, Galkin S V, et al. Journal of Marine Systems, 2012. [7] Daly K L, Byrne R H, Dickson A G, et al. Marine Technology Society Journal, 2004, 38(2): 121. [8] Tivey M K. Oceanography, 2007，20(1)：50. [9] Fortes F J, Laserna J J. Spectrochimica Acta Part B, 2010, 65(12): 975. [10] Sakka T, Oguchi H, Masai S, et al. Applied Physics Letters, 2006, 88(6): 061120. [11] Thornton B, Masamura T, Takahashi T, et al. Oceans, 2012, IEEE, 2012: 1. [12] Hou H, Tian Y, Li Y, et al. J. Anal. At. Spectrom., 2013. [13] WU Jiang-lai, LU Yuan, LI Ying, et al(吴江来，卢 渊，李 颖，等). Optoelectronics Letters(光电子快报), 2011, 7: 65. [14] Michel A P M, Lawrence-Snyder M, Angel S M, et al. Applied Optics, 2007, 46(13): 2507. [15] Docchio F, Regondi P, Capon M R C, et al. Applied Optics, 1988, 27(17): 3661. [16] FENG Shi-zuo, LI Feng-qi, LI Shao-jing(冯士筰, 李凤岐, 李少菁). Introduction to Ocean Science(海洋科学导论). Beijing: Higher Education Press(北京: 高等教育出版社), 1999. [17] DENG Ru-ru, HE Ying-qing, QIN Yan, et al(邓孺孺，何颖清，秦 雁，等). Journal of Remote Sensing(遥感学报), 2012, 16(1): 192.
