Gondal Mohammed Ashraf, Dastageer Mohamed Abdulkader, Maslehuddin Mohammed, Alnehmi Abdul Jabar, Al-Amoudi Omar Saeed Baghabra
Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Box 504, Dhahran-31261, Saudi Arabia.
Appl Opt. 2011 Jul 10;50(20):3488-96. doi: 10.1364/AO.50.003488.
The presence of chloride in reinforced concrete can cause severe damage to the strength and durability of buildings and bridges. The detection of chloride in concrete structures at early stages of the corrosion buildup process is, therefore, very important. However, detection of chlorine in trace amounts in concrete is not a simple matter. A dual-pulsed laser-induced breakdown spectrometer (LIBS) has been developed at our laboratory for the detection of chloride contents in reinforced concrete by using two atomic transition lines of neutral chlorine (Cl I) at 594.8 and 837.5 nm. A calibration curve was also established by using standard samples containing chloride in known concentration in the concrete. Our dual-pulsed LIBS system demonstrated a substantial improvement in the signal level at both wavelengths (594.8 and 837.5 nm). However, the new atomic transition line at 594.8 nm shows a significant improvement compared to the line at 837.5 nm in spite of the fact that the relative intensity of the former is 0.1% of the latter. This weak signal level of the 837.5 nm transition line of chlorine can be attributed to some kind of self-absorption process taking place in the case of the concrete sample.
钢筋混凝土中氯化物的存在会对建筑物和桥梁的强度及耐久性造成严重损害。因此，在腐蚀形成过程的早期阶段检测混凝土结构中的氯化物非常重要。然而，检测混凝土中痕量的氯并非易事。我们实验室已开发出一种双脉冲激光诱导击穿光谱仪（LIBS），通过利用中性氯（Cl I）在594.8和837.5 nm处的两条原子跃迁线来检测钢筋混凝土中的氯化物含量。还通过使用混凝土中含有已知浓度氯化物的标准样品建立了校准曲线。我们的双脉冲LIBS系统在两个波长（594.8和837.5 nm）处的信号水平都有显著提高。然而，尽管594.8 nm处新的原子跃迁线的相对强度仅为837.5 nm处跃迁线的0.1%，但与837.5 nm处的跃迁线相比，它仍有显著改善。氯在837.5 nm处跃迁线的这种微弱信号水平可归因于混凝土样品中发生的某种自吸收过程。
