초록 ▼

Self-normalization of laser spectrometers is provided by I″/I laser modulation and detection. A single tunable diode laser is frequency modulated by a high S/N ratio triangle wave, mechanically chopped, passed through an isothermal in-line gas and reference chamber absorption cell, and synchronously

Self-normalization of laser spectrometers is provided by I″/I laser modulation and detection. A single tunable diode laser is frequency modulated by a high S/N ratio triangle wave, mechanically chopped, passed through an isothermal in-line gas and reference chamber absorption cell, and synchronously detected to provide the I″and I signals. The preferred embodiment discloses isotopic ratio measurements. The invention has application to quantitative trace gas measurements generally.

대표청구항 ▼

A method for determining isotopic ratios by absorption spectrometry, comprising the steps of: aligning a sample gas having the isotopic ratio to be determined and a reference gas having a known isotopic ratio in thermodynamic equilibrium along an optical path; irradiating the sample and reference ga

A method for determining isotopic ratios by absorption spectrometry, comprising the steps of: aligning a sample gas having the isotopic ratio to be determined and a reference gas having a known isotopic ratio in thermodynamic equilibrium along an optical path; irradiating the sample and reference gases with a laser beam; measuring the absorption of the laser beam by the combined sample and reference gases; removing the sample gas from the optical path; irradiating the reference gas with the laser beam; measuring the absorption of the laser beam by the reference gas; and subtracting from the measurement of the combined sample and reference gases the measurement of the reference gas to provide the isotopic ratio of the sample gas.