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Development of an analytical technique for isotopic ratio of carbon and oxygen in carbonates using a laser-probe method.

使用激光探针方法开发碳酸盐中碳和氧同位素比的分析技术。

基本信息

批准号：
10640473
负责人：
AKAGI Tasuku
金额：
$ 1.41万
依托单位：
Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
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

项目摘要

The objective of this project is to develop a method to analyze the isotopic ratio of carbon and oxygen in any selected spot of carbonate samples during microscopic observation. Following works were carried out to approach the objective.1. The vacuum line was constructed to fire sample with an Nd-YAG laser under vacuum and to purify produced carbon dioxide. The sample chamber, to hold samples to be fired, was made using quartz and aluminum.2. A solid standard carbonate sample, whose isotopic composition was known, was attempted to prepare by pressing the mixture of carbonate powder and sodium chloride powder. This procedure produced the carbonate pellets with good strength, but by the radiation of the laser, unknown gases were generated besides carbon dioxide, which impaired the following isotopic analysis.3. A new standard pellet was made using calcium carbonate only. This was very brittle, but was proved to have strength just enough to survive the laser firing.4. The yield of carbon dioxide increased with smaller interval of laser pulses, implied the re-combination of carbon dioxide with calcium oxide in the fired sample. The higher power tended to give the greater yield, but the increasing rate became the smaller with the higher power.5. The isotopic ratio of carbon and oxygen varied with the yields, approaching constant ratios, which are fairy closed to the pre-determined values obtained by the conventional method, but are still different by a few permil. The bias was not needed to apply in the oxygen isotopic ratio, which was necessary in the conventional method. The reproducibility is as much as 0.5 permil, which was poorer than the conventional method.Fairy satisfactory results were obtained to show that the new method was promising.

本计画的目的是发展一种在显微镜观察下分析碳酸盐岩样品中任意点的碳氧同位素比值的方法。为实现这一目标，开展了以下工作：1.构建真空管线以在真空下用Nd-YAG激光器烧制样品并纯化产生的二氧化碳。样品室，以保持样品被解雇，是使用石英和铝。2.用碳酸盐粉末和氯化钠粉末混合物压制成固体碳酸盐标准样品，其同位素组成是已知的。这种方法生产的碳酸盐颗粒具有良好的强度，但由于激光的辐射，除了二氧化碳外，还产生了未知气体，这影响了随后的同位素分析。仅使用碳酸钙制备新的标准粒料。这是非常脆的，但被证明有足够的强度，以生存的激光射击。4.随着激光脉冲间隔的减小，CO2的产率增加，这意味着CO2与煅烧样品中的氧化钙重新结合。功率越大，产量越高，但增幅越小.碳氧同位素比值随产率的变化而变化，接近恒定比值，与常规方法测得的预定值相当接近，但仍相差几个百分点。氧同位素比值测定不需要常规方法所需的偏置。方法的重现性为0.5permil，比常规方法差，结果令人满意，表明新方法是有前途的。