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Development of photoacoustic spectrometry for measurement of isotope ratio.

开发用于测量同位素比的光声光谱法。

基本信息

批准号：
10358014
负责人：
KAWASAKI Masahiro
金额：
$ 17.54万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10358014/
关键词：
water third overtone pulsed lasar photoacoustic isotope PAS microphone fourth overtone

项目摘要

A photoacoustic spectroscopy technique is applied to the isotope ratio measurement of ィイD116ィエD1O and ィイD118ィエD1O in water-vapor samples, using a pulsed tunable dye laser pumped by Nd : YAG laser. The third overtone band (3vィイD2OHィエD2) of water molecules near 950 nm was investigated, for two standard water samples, V-SMOW and SLAP. We identified the absorption lines of HィイD22ィエD2ィイD116ィエD1O and HィイD22ィエD2ィイD118ィエD1O in the photoacoustic spectra that we measured by using the HITRAN database. We measured the difference in the ィイD118ィエD1O/ィイD116ィエD1O isotope ratios for V-SMOW and SLAP, using the photoacoustic method. For each water isotope (HィイD22ィエD2ィイD116ィエD1O and HィイD22ィエD2ィイD118ィエD1O) peak we made 128 times averaging of the photoacoustic wave on the oscilloscope and scanned the laser wavelength within a selected range in 0.002 nm increments. The measurement time was 7000 s for each sample. The value obtained for the difference between the two samples is δィイD118ィエD1OィイD2SMOWィエD2=-55±10‰, whereas the value measured with a conventional isotope mass spectrometer is δィイD118ィエD1O=-55.5‰. That δ-value was certainly an improvement on the previous work. However, the obtained δ-value has a relatively large deviation, because the deviation should be less than 1-2‰ for practical use. Further improvements are necessary to reduce the deviation. The large deviation comes mainly from the low signal-to-noise ratio in the photoacoustic spectra.

利用Nd：YAG激光泵浦的脉冲可调谐染料激光器，将光声光谱技术应用于水汽样品中氘代D116氘代D1 O和氘代D118氘代D1 O同位素比值的测量。研究了两种标准水样V-SMOW和SNOW在950 nm附近水分子的第三泛音带（3v荧光D_2OH荧光D_2）。利用HITRAN数据库，我们在光声光谱中确定了H D22 D2 D116 D1 O和H D22 D2 D118 D1 O的吸收线。我们使用光声方法测量了V-SMOW和SNOW的D118-D1 O/D116-D1 O同位素比值的差异。对于每个水同位素（H_（12）D22_（12）D2_（12）D116_（12）D1 O和H_（12）D22_（12）D2_（12）D118_（12）D1 O）峰，我们在示波器上对光声波进行128次平均，并以0.002 nm的增量在选定范围内扫描激光波长。每个样品的测量时间为7000 s。两个样品之间的差值为δ 100 D118 δ 100 D1 O δ 2SMOW δ 100 D2=-55 10 ‰，而用常规同位素质谱仪测量的值为δ 100 D118 δ 100 D1 O =-55.5‰。这个δ值无疑是对以前工作的改进。但得到的δ值有较大的偏差，因为实际使用时偏差应小于1-2‰。需要进一步改进以减少偏差。大的偏差主要来自于光声光谱中的低信噪比。