Abstract：
The paper presents a technique for measuring the concentration of 13CH4 in natural methane using Raman spectroscopy. The peak positions and the relative scattering cross-sections of the Q-branches for the most intense vibrational bands of 13CH4 are determined. Features of the 13CH4/12CH4 ratio measurement methods using Q-branches of the ν1 and ν3 bands were considered. It was shown that the 13CH4/12CH4 ratio can be determined by simulation of the ν3 bands of these molecules without the use of experimental spectra. In our experiments the measurement error of δ13C value was 10 ‰ using the 100-s exposure spectrum at a gas pressure close to 1 atm recorded on the developed Raman spectrometer. In addition, the Raman spectra of alkanes (up to n-hexane) in the range of 2850-3050 cm-1 at a resolution of 0.4 cm-1 are presented, and their integrated intensities in the ranges of the characteristic bands of 13CH4 and 12CH4 are provided. The data obtained make it possible to expand the capabilities of Raman gas analyzers in the mud gas logging industry.
摘要：
本文提出了一种使用拉曼光谱测量天然甲烷中13CH4浓度的技术。确定了13CH4最强振动带的Q分支的峰位置和相对散射截面。考虑了使用ν1和ν3带的Q分支的13CH4/12CH4比率测量方法的特征。表明，可以通过模拟这些分子的ν3带而不使用实验光谱来确定13CH4/12CH4的比率。在我们的实验中，在开发的拉曼光谱仪上记录的接近1atm的气压下，使用100s曝光光谱，δ13C值的测量误差为10‰。此外,显示了2850-3050cm-1范围内的烷烃（直至正己烷）的拉曼光谱，分辨率为0.4cm-1，以及它们在13CH4和12CH4的特征带范围内的积分强度被提供。获得的数据使扩大拉曼气体分析仪在泥浆气测录井行业中的能力成为可能。
