Open-ended photoacoustic cells: application to two-layer samples using pulse laser-induced photoacoustics.
Open-ended photoacoustic cells: application to two-layer samples using pulse laser-induced photoacoustics.
复制标题
开放式光声池：使用脉冲激光诱导光声学应用于两层样品。
DOI：
10.1021/ac9701851
复制
发表时间：
1998
影响因子：
7.4
通讯作者：
T. Hobo
中科院分区：
文献类型：
--
作者：
Katsumi Uchiyama;K. Yoshida;Xing;T. Hobo
为了测量原位样品之间的差异，构建了两种类型的开放式光声池。一种是带有差动麦克风的差动开口光声池，它通过两个波导连接两个等效的开口光声池腔。另一种设计使用单端开放的光声细胞室，每个室都有一个电容式麦克风。一对这些被用来通过减去信号来抑制背景信号。这些细胞的性能进行了比较，一个传统的光声装置与斩波器。苏丹红的检测限分别为1.29和2.35 ng的差分开放式细胞和一个单一的开放式细胞，分别。然后将光声池应用于脉冲模式操作，使用氮激光器作为脉冲光源。激光束通过石英光纤引入光声池。使用这种仪器设置，深度剖面分析进行了两层样品的聚（甲基丙烯酸甲酯）（PMMA）或聚苯乙烯（PS）薄膜。信号延迟时间与膜厚呈线性关系。信号的延迟时间（τ）用薄膜的热扩散率（κ/cm（2）s（-）（1））表示为τ（ms）<$（2.25 × 10（-3））×（μm）κ（-1/2）。该方法成功地测量了透明表面层的厚度。我们应用这种技术观察了在长波长紫外线照射下晒黑的人体皮肤表面下某种发色团的产生，这种发色团被认为是黑色素。
To measure the difference between samples in situ, two types of open-ended photoacoustic cells were constructed. One type was a differential open-ended photoacoustic cell with a differential microphone, which connected two equivalent open-ended cell chambers through two waveguides. The other design used single open-ended photoacoustic cell chambers, each with an electric condenser microphone. A pair of these was used to suppress background signal by subtraction of the signals. The performance of these cells was compared to that of a conventional photoacoustic apparatus with a chopper. Detection limits of Sudan red for those cells were about 1.29 and 2.35 ng for a differential open-ended cell and a single open-ended cell, respectively. The photoacoustic cells were then applied to the pulse mode operation, using a nitrogen laser as a pulse light source. The laser beams were led to the photoacoustic cells through quartz optical fibers. Using this instrument setup, depth profiling analysis was carried out for two-layer samples made of poly(methyl methacrylate) (PMMA) or polystyrene (PS) films. A linear relationship was obtained between the signal delay time and the film thickness. The delay time of the signal (τ) was expressed in terms of the thermal diffusivity (κ/cm(2) s(-)(1)) of the film as τ (ms) ≅ (2.25 × 10(-3)) x (μm) κ(-1/2). The method was successful in measuring the thickness of transparent surface layers. We applied this technique to observe the generation of a certain chromophore, thought to be melanin, under the surface of human skin tanned by exposure to long-wavelength UV light.