Fahad Muhammad, Farooq Zahid, Abrar Muhammad
Appl Opt. 2019 May 1;58(13):3501-3508. doi: 10.1364/AO.58.003501.
Laser-induced breakdown spectroscopy (LIBS) has been employed for the qualitative and quantitative analysis of quartz-bearing limestone using two different calibration-free LIBS methods, that is, one-line calibration-free LIBS (OLCF-LIBS) and self-calibration LIBS (SC-LIBS) methods in conjunction with energy-dispersive x-ray spectroscopy (EDS) and x-ray fluorescence spectroscopy (XRF). The plasma is generated by focusing a Q-switched Nd:YAG laser (1064 nm, 134 mJ pulse energy, 9 ns pulse duration) in air under atmospheric pressure. Spectral analysis revealed the presence of Ca, Si, and Mg. Plasma temperature is deduced using the neutral spectral lines of pertinent elements using the Boltzmann plot method, and an average value of 3462 K is used for the quantitative analysis. An average value for electron number density is calculated as (1.3±0.3)×10 cm from the Stark broadening of isolated neutral Ca, Si, and Mg lines and a singly ionized Ca line. The elemental composition determined by different LIBS methods and other traditional analytical techniques are OLCF-LIBS (Ca, 71.82%; Si, 28.12%; Mg, 0.048%), SC-LIBS (Ca, 69.19%; Si, 28.92%; Mg, 1.87%), EDS (Ca, 68.86%; Si, 30.12%; Mg, 0.32%), and XRF (Ca, 68.62%; Si, 27.18%; Mg, 1.56%). By comparing the results of both CF-LIBS methods along with EDS and XRF, it is demonstrated that the SC-LIBS method is more appropriate than the OLCF-LIBS and gives compositions comparable with that determined by EDS and XRF and, hence, displays its ability as a powerful tool for the compositional analysis of complex minerals.
激光诱导击穿光谱法（LIBS）已被用于对含石英石灰岩进行定性和定量分析，采用了两种不同的无校准LIBS方法，即单线无校准LIBS（OLCF-LIBS）和自校准LIBS（SC-LIBS）方法，并结合能量色散X射线光谱法（EDS）和X射线荧光光谱法（XRF）。通过在大气压下的空气中聚焦调Q Nd:YAG激光（1064 nm，134 mJ脉冲能量，9 ns脉冲持续时间）来产生等离子体。光谱分析揭示了钙、硅和镁的存在。使用玻尔兹曼图法通过相关元素的中性光谱线推导等离子体温度，并将3462 K的平均值用于定量分析。根据孤立的中性钙、硅和镁谱线以及单电离钙谱线的斯塔克展宽，计算出电子数密度的平均值为(1.3±0.3)×10 cm。通过不同LIBS方法和其他传统分析技术确定的元素组成分别为：OLCF-LIBS（钙，71.82%；硅，28.12%；镁，0.048%），SC-LIBS（钙，69.19%；硅，28.92%；镁，1.87%），EDS（钙，68.86%；硅，30.12%；镁，0.32%），以及XRF（钙，68.62%；硅，27.18%；镁，1.56%）。通过比较两种无校准LIBS方法以及EDS和XRF的结果，表明SC-LIBS方法比OLCF-LIBS更合适，并且给出的成分与EDS和XRF测定的结果相当，因此，显示出其作为复杂矿物成分分析有力工具的能力。
