DEVELOPMENT OF DETECTION METHOD FOR MEASURING AMBIENT NO CONCENTRATION USING HIGH SENSITIVE LASER SPECTROSCOPIC TECHNIQUE

高灵敏激光光谱技术测量环境中NO浓度检测方法的研制

• 批准号: 07454147
• 负责人: KAJII Yoshizumi
• 金额: $ 4.86万
• 依托单位: RESEACH CENTER FOR ADVANCED SCIENCE AND TECHNOLOGY,THE UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454147/
• 关键词: SUPER SONIC FREE JET; RETPI; UV-PULSE LASER; ROTATIONAL TEMPERATURE; INTERFERENCE OF NO_2; COUNTING TECHNIOUE; LIMIT OF DETECTION; NO; 2光子共鳴イオン化(RE2PI); 大気測走; 高感度測走; レーザーイオン化; 超音速分子線法

we designed and constructed vacuum chamber and vacuum system for measuring ambient NO concentration. The laser system of tunable dye laser pumped by 3rd harmonic of pulsed nd : YAG laser was constructed. The out-put of dye laser was doubled to excite NO molecule into single ro-vibronic level. The analysis of rotationnal temperature was done to determine rotational temperature to be 25 K under X/D of 70. we reconfirmed resonance enhanced two photon ionization (RETPI) process rom the laser power dependence experiment showing index of 1.75. we employed ion counting system for detection of ion signals to increase S/N ratio. we found almost of two order of magnitude improvement of sensitivity by replacement of detection system from analog-to-digital operation to ion counting operation. we confirmed linear response of ion signal with NO concentration up to 200 ppb. In the chemical. interference of NO_2, the sensitivity of NO_2 is ca.2% compared to that of NO.This shows the improvement of selectivity by the cooling process. The limit of detection was estimated to be 16 pptv with an integration time of 1 min.

我们设计并建造了用于测量环境NO浓度的真空室和真空系统。建立了脉冲Nd：YAG激光三倍频泵浦可调谐染料激光器的激光系统。染料激光器的输出功率加倍，将NO分子激发到单振子能级。通过对旋转温度的分析，确定了X/D = 70时的旋转温度为25 K。我们从激光功率依赖性实验中再次证实了共振增强双光子电离（RETPI）过程，其指数为1.75。我们采用离子计数系统检测离子信号，以提高信噪比。我们发现，通过将检测系统从模拟-数字操作替换为离子计数操作，灵敏度几乎提高了两个数量级。我们证实了离子信号与NO浓度高达200 ppb的线性响应。在化学物质中。NO_2的灵敏度约为NO的2%左右，说明冷却过程提高了选择性。估计检测限为16 pptv，积分时间为1 min。