Filho Milton B, da Silva Marcelo G, Sthel Marcelo S, Schramm Delson U, Vargas Helion, Miklós Andras, Hess Peter
Laboratório de Ciências Físicas, Centro de Ciência e Technologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes-RJ, Brazil.
Appl Opt. 2006 Jul 10;45(20):4966-71. doi: 10.1364/ao.45.004966.
A pulsed quantum-cascade distributed-feedback laser, temperature tunable from -41 degrees C to +31.6 degrees C, and a resonant differential photoacoustic detector are used to measure trace-gas concentrations to as low as 66 parts per 10(9) by volume (ppbv) ammonia at a low laser power of 2 mW. Good agreement between the experimental spectrum and the simulated HITRAN spectrum of NH3 is found in the spectral range between 1046 and 1052 cm(-1). A detection limit of 30 ppbv ammonia at a signal-to-noise ratio of 1 was obtained with the quantum-cascade laser (QCL) photoacoustic (PA) setup. Concentration changes of approximately 50 ppbv were detectable with this compact and versatile QCL-based PA detection system. The performance of the PA detector, characterized by the product of the incident laser power and the minimum detectable absorption coefficient, was 4.7 x 10-9 W cm(-1).
一台脉冲量子级联分布反馈激光器，温度可在-41摄氏度至+31.6摄氏度之间调节，以及一个共振差分光声探测器，用于在2毫瓦的低激光功率下测量痕量气体浓度，低至体积分数为66×10⁻⁹（ppbv）的氨。在1046至1052厘米⁻¹的光谱范围内，实验光谱与NH₃的模拟HITRAN光谱之间发现了良好的一致性。使用量子级联激光（QCL）光声（PA）装置，在信噪比为1时获得了30 ppbv氨的检测限。使用这种紧凑且通用的基于QCL的PA检测系统可检测到约50 ppbv的浓度变化。PA探测器的性能以入射激光功率与最小可检测吸收系数的乘积为特征，为4.7×10⁻⁹瓦·厘米⁻¹。
