Wavelength-meter controlled cavity ring-down spectroscopy: high-sensitivity detection of trace moisture in N2 at sub-ppb levels
Wavelength-meter controlled cavity ring-down spectroscopy: high-sensitivity detection of trace moisture in N2 at sub-ppb levels
复制标题
波长计控制腔衰荡光谱：高灵敏度检测亚 ppb 水平的 N2 中的痕量水分
DOI：
10.1016/j.sna.2016.02.016
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
H. Abe
中科院分区：
文献类型：
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作者：
K. Hashiguchi;D. Lisak;A. Cygan;R. Ciurylo;H. Abe
本文提出了一种相对简单的腔衰荡光谱技术（CRDS）中激光与高精细度腔的有效耦合方法。使用高分辨率波长计将探测激光器的频率耦合到腔的谐振频率。所获得的振铃事件的测量的重复率为150 Hz。噪声等效吸收系数为5.2 × 10− 11 cm −1Hz− 12，最小可探测吸收系数为6.7 × 10− 12 cm −1（70 s平均后）。我们发现波长计的指示（读数）存在显著偏差，这可能是由于干涉仪内部残留水分引起的色散。残留水分的露点估计为−13.9 °C。通过基于实验获得的数据校正偏差，在15分钟内在7179.537 cm-1-7183.330 cm-1（包含539个光谱点）的范围内有效地记录H2O的近红外（1393 nm）光谱。对2小时内获得的8个光谱的平均值进行分析，结果显示基线噪声（一个标准偏差）为1.3 × 10− 11 cm −1，相当于物质的摩尔分数（摩尔分数）中N2中H2O的浓度为0.012 nmol/mol（0.012 ppb）。
We present a relatively simple technique to efficiently couple a laser to a high-finesse cavity in cavity ring-down spectroscopy (CRDS). The frequency of the probe laser is coupled to a resonant frequency of the cavity using a high-resolution wavelength meter. The repetition rate of measurement of the ring-down events obtained is 150 Hz. We attain a noise equivalent absorption coefficient of 5.2 × 10−11cm−1Hz−1/2and a minimum detectable absorption coefficient of 6.7 × 10−12cm−1(after 70 s averaging). We find significant deviations in the indications (readings) of the wavelength meter, probably because of dispersion due to residual moisture inside the interferometer. The dew point of the residual moisture is estimated to be −13.9 °C. By correcting the deviations on the basis of experimentally obtained data, a near-infrared (1393 nm) spectrum of H2O is efficiently recorded in the range of 7179.537 cm−1–7183.330 cm−1(containing 539 spectral points) in 15 min. Analysis of the average of the eight spectra acquired in 2 h shows a baseline noise (one standard deviation) of 1.3 × 10−11cm−1, corresponding to 0.012 nmol/mol (0.012 ppb) of H2O in N2in amount-of-substance fraction (mole fraction).