High Resolution and High Sensitivity Measurement of Methane at 1.51 μm

The high-resolution absorption spectrum of CH4 at 1.51 μm 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 6608 cm−1 to 6625 cm−1. Special attention is paid on the determination of the line positions, and the accuracy is better than ±0.002 cm−1. A minimum measurable absorption of 2.1×10−8 (3σ) has been achieved based on the measured direct absorption spectroscopy.