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.

采用 Nd: YAG 激光器泵浦的脉冲可调谐染料激光器，采用光声光谱技术测量水蒸气样品中的 D116D1O 和 D118D1O 的同位素比，研究了水分子在 950 nm 附近的第三泛音带 (3v D2OHD2)。，对于两个标准水样，V-SMOW 和 SLAP。我们使用 HITRAN 数据库测量了光声光谱中的 HiD22D2D116D1O 和 HiD22D2D118D1O 的吸收线，并使用对于每个水同位素（HiD22D2D116D1O 和 HD22D2D118D1O）峰，我们在示波器上对光声波进行了 128 次平均，并以 0.002 nm 的增量在选定范围内扫描激光波长，每次测量时间为 7000 秒。两个样品之间的差异值为 δD118D1OD2SMOWD2=-55±10‰，而用传统同位素质谱仪测量的值为 δD118 D1O=-55.5‰，这个 δ 值肯定比之前有所改进。然而，得到的δ值有较大的偏差，因为偏差应该。实际使用中需要进一步改进以减少偏差。较大的偏差主要来自于光声光谱的低信噪比。