A critical evaluation of the chlorine quantification method based on molecular emission detection in LIBS

Individual Micron-Sized Aerosol Qualitative Analysis-Combined Raman Spectroscopy and Laser-Induced Breakdown Spectroscopy by Optical Trapping in Air

“…Raman spectroscopy also cannot measure ionic compounds. However, when halogens combine with alkaline earth or other elements to form free radicals (spectral peaks are mainly distributed in the visible region), their detection sensitivity is much higher than that of atomic lines. − We measured the free radical spectra of a single CaCl 2 and fluorite particle, as shown in Figure . In Figure a, the peaks of CaCl radicals can be obtained at 593.56 nm, and Ca­(HCO 3 ) 2 is added to generate more CaCl radicals.…”

Improving Cl determination in cements by molecular LIBS using noble gas-enriched atmospheres and new approaches for interference removal

“…To evaluate the validity of the interference elimination procedure for all Cl concentrations, the calibration samples (K01–K12) were measured in air using a delay time of 50 μs and a gate time of 15 μs. This delay time was chosen following the results obtained in a previous work 44 which showed for this delay a good balance between the already low atomic emission intensities of Na and Ca and the still high molecular emission of CaCl in gypsum samples. On the other hand, the gate in this study was set for the spectrum of the sample with the highest NaCl content (K12) to have its maximum intensity under the limit of the linear response of the detector (40 000 counts).…”

“…A detailed Cl quantification protocol was recently evaluated using CaCl emission (B 2 Σ → X 2 Σ electronic transition, Δ ν = 0 sequence), showing that spectral interference from CaO could be removed by using a blank sample, and employing variable integration ranges led to an improved sensitivity and a reduced uncertainty. 44 Nevertheless, this procedure is not enough for cement samples due to their high amount of sodium content, as the bright orange doublet which characterizes the Na I emission spectrum (∼589 nm), significantly interferes with the B 2 Σ → X 2 Σ Δ ν = 0 emission of CaCl (∼593 nm). In addition, blanks containing suitable amounts of Na are often not available for the analysis of such samples, so further efforts are needed in order to remove this interference.…”

Fast detection of hazardous chlorinated volatile organic compounds via laser-induced breakdown spectroscopy

“…Fortunately, the LIBS molecular spectra lie in the visible region, which can be detected in the air environment. 17,18 But, the intrinsic molecular spectra in VOCs are weak, which can't meet the requirements for high-precision analysis of Cl. 19 In this work, a novel approach is established to achieve a stable, reliable molecular emission of CaCl with high intensity.…”

“…Fortunately, the LIBS molecular spectra lie in the visible region, which can be detected in the air environment. 17,18 But, the intrinsic molecular spectra in VOCs are weak, which can't meet the requirements for high-precision analysis of Cl. 19…”