Larsson Kajsa, Aldén Marcus, Bood Joakim
Division of Combustion Physics, Lund University, Lund, Sweden.
Appl Spectrosc. 2017 Sep;71(9):2118-2127. doi: 10.1177/0003702817702386. Epub 2017 Apr 27.
A concept based on photofragmentation laser-induced fluorescence (PFLIF) is for the first time demonstrated for simultaneous detection of hydrogen peroxide (HO) and water (HO) vapor in various mixtures containing the two constituents in a bath of argon gas. A photolysis laser pulse at 248 nm dissociates HO into OH fragments, whereupon a probe pulse, delayed 100 ns and tuned to an absorption line in the AΣ (v = 1) ← XΠ(v = 0) band of OH near 282 nm, induces fluorescence. The total OH fluorescence reflects the HO concentration, while its spectral shape is utilized to determine the HO concentration via a model predicting the ratio between the fluorescence intensities of the AΣ (v = 1) → XΠ(v = 1) and the AΣ (v = 0) → XΠ(v = 0) bands. The HO detection scheme requires that the bath gas has a collisional cross-section with OH(A) that is significantly lower than that of HO, which is the case for argon. Spectrally dispersed OH fluorescence spectra were recorded for five different HO/HO/Ar mixtures; the HO concentration in the range of 30-500 ppm and the HO concentration in the range of 0-3%. Fluorescence intensity ratios predicted by the model for these mixtures agree very well with corresponding experimental data, which thus validates the model. The concept was also demonstrated for two-dimensional imaging, using two intensified charge-coupled device (CCD) cameras for signal detection. Water content was here sensed through the different temporal characteristics of the two fluorescence bands by triggering the two cameras so that one captures the total OH fluorescence while the other one captures only the early part, which mainly stems from AΣ (v = 1) → XΠ(v = 1) fluorescence. Hence, the HO concentration is reflected by the image of the camera recording the total OH fluorescence, whereas HO concentration is extracted from the ratio between the two camera images. Quantification of the concentrations was carried out based on calibration measurements performed in known mixtures of HO (30-500 ppm) and HO (0-3%) in bulk argon. The detection limits for single-shot imaging are estimated to be 20 ppm for HO and 0.05% for HO. The authors believe that the concept provides a valuable asset in, for example, pharmaceutical or aseptic food packaging applications, where HO/HO vapor is routinely used for sterilization.
首次展示了一种基于光解离激光诱导荧光（PFLIF）的概念，用于在含有过氧化氢（HO）和水蒸气（HO）两种成分的氩气浴中同时检测各种混合物中的过氧化氢和水蒸气。248 nm的光解激光脉冲将HO分解为OH碎片，随后一个延迟100 ns并调谐到OH在282 nm附近的AΣ（v = 1）←XΠ（v = 0）带中的一条吸收线的探测脉冲会诱导荧光。总的OH荧光反映了HO的浓度，而其光谱形状则通过一个预测AΣ（v = 1）→XΠ（v = 1）和AΣ（v = 0）→XΠ（v = 0）带的荧光强度之比的模型来确定HO的浓度。HO检测方案要求浴气与OH（A）的碰撞截面明显低于HO的碰撞截面，氩气就是这种情况。记录了五种不同的HO/HO/Ar混合物的光谱分散OH荧光光谱；HO浓度范围为30 - 500 ppm，HO浓度范围为0 - 3%。该模型预测的这些混合物的荧光强度比与相应的实验数据非常吻合，从而验证了该模型。还使用两个增强型电荷耦合器件（CCD）相机进行信号检测，对该概念进行了二维成像演示。通过触发这两个相机，利用两个荧光带不同的时间特性来检测含水量，使得一个相机捕捉总的OH荧光，而另一个相机只捕捉主要源于AΣ（v = 1）→XΠ（v = 1）荧光的早期部分。因此，记录总的OH荧光的相机图像反映HO的浓度，而HO浓度则从两个相机图像的比值中提取。基于在大量氩气中已知的HO（30 - 500 ppm）和HO（0 - 3%）混合物中进行的校准测量来进行浓度定量。单次成像的检测限估计为HO为20 ppm，HO为0.05%。作者认为，该概念在例如制药或无菌食品包装应用中提供了一项有价值的资产，在这些应用中，HO/HO蒸气通常用于灭菌。
