High Resolution and High Sensitivity Measurement of Methane at 1.51μm

The high-resolution absorption spectrum of CH₄ at 1.51μm is observed by direct absorption spectroscopy technique with a White absorption cell. Multi-peak fitting technique is adopted to reveal line positions and line intensities of CH₄ from 6608cm^-1 to 6625cm^-1. Special attention is paid on the determination of the line positions, and the accuracy is better than ±0.002cm^-1. A minimum measurable absorption of 2.1×10^-8 (3σ) has been achieved based on the measured direct absorption spectroscopy.