On-line multicomponent trace-gas analysis with a broadly tunable pulsed difference-frequency laser spectrometer.
On-line multicomponent trace-gas analysis with a broadly tunable pulsed difference-frequency laser spectrometer.
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DOI：
10.1364/ao.38.004691
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发表时间：
1999-07
期刊：
影响因子：
1.9
通讯作者：
M. Seiter;M. Sigrist
中科院分区：
文献类型：
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作者：
M. Seiter;M. Sigrist
报道了一种新型自动化室温激光光谱仪的设计和应用。该紧凑型仪器基于块状 LiNbO(3) 的差频生成。该仪器采用可调谐连续波外腔二极管激光器 (795-825 nm) 和脉冲二极管泵浦 Nd:YAG 激光器 (1064 nm)。生成的中红外纳秒脉冲具有 50 微瓦峰值功率和 6.5 kHz 重复率，在 3.16 至 3.67 微米之间连续可调，耦合到 36 米多通道池中进行光谱研究。甲烷的在线测量浓度在 200 ppb（10(9) 中的摩尔分数）到大约 1% 之间，显示出 7 个数量级的大动态范围。此外，还报告了对含有五种痕量气体和水蒸气的混合物进行计算机控制的多组分分析，总响应时间为 90 秒，平均时间仅为约 30 秒。在平均 60 秒的时间内实现了 1.1 x 10(-7) cm(-1) 的最小可检测吸收系数，使许多重要痕量气体的检测限达到 ppb 范围，例如 CH(4)、C(2)H(6)、H(2)CO、NO(2)、N(2)O、HCl、HBr、CO 和 OCS。
The design and application of a novel automated room-temperature laser spectrometer are reported. The compact instrument is based on difference-frequency generation in bulk LiNbO(3). The instrument employs a tunable cw external-cavity diode laser (795-825 nm) and a pulsed diode-pumped Nd:YAG laser (1064 nm). The generated mid-IR nanosecond pulses of 50-microW peak power and 6.5-kHz repetition rate, continuously tunable from 3.16 to 3.67 microm, are coupled into a 36-m multipass cell for spectroscopic studies. On-line measurements of methane are performed at concentrations between 200 ppb (parts in 10(9) by mole fraction) and approximately 1%, demonstrating a large dynamic range of 7 orders of magnitude. Furthermore computer-controlled multicomponent analysis of a mixture containing five trace gases and water vapor with an overall response time of 90 s at an averaging time of only approximately 30 s is reported. A minimum detectable absorption coefficient of 1.1 x 10(-7) cm(-1) has been achieved in an averaging time of 60 s, enabling detection limits in the ppb range for many important trace gases, such as CH(4), C(2)H(6), H(2)CO, NO(2), N(2)O, HCl, HBr, CO, and OCS.