Determination of the partial and total pressures of the mixed gases in atomic vapor cells by optical absorption

Abstract

We study the partial and total pressures of the mixed gases in a rubidium vapor cell through its absorption spectrum under the influence of the natural broadening, the self-broadening, the pressure broadening, the pressure shift, and the Doppler broadening. A comprehensive model of the absorption coefficient on Rb D2 line is developed, which takes into account the influence of multiple gas species. The importance of light intensity selection and frequency calibration to obtain accurate experimental results are discussed. The accurate abundances are deduced from the experimentally measured absorption spectra of vacuum cells, and are used to optimize the abundance parameters in our model. We fit the experimentally measured absorption spectrum of a gas-filled cell to the optimized model, and get a root mean square error better than 0.1%. The extracted partial pressures indicate that the mixture ratio agrees well with the designed value, while the total pressure has an increment of about 17% of its nominal value. We further estimate the helium leakage amount of a cell to be 89.1 Torr for six months. Moreover, by using a series of absorption spectra generated by our model as benchmarks, we evaluate the effectiveness of the commonly used single- and double- Lorentzian fitting models and give some suggestions on using the double Lorentzian model.

High precision wavelength measurement system based on FP cavity and saturation absorption peaks

“…Details of the model setup and curve fitting are given in. 11 The fitted results are shown in figure 6. Through curve fitting, all four components of the absolute absorption spectrum of the target cell are decomposed.…”

Microwave-to-optical conversion in a room-temperature 87Rb vapor for frequency-division multiplexing control

“…The frequency tunability of the generated signal field results from the existence of a large Doppler width at room temperature. While this work uses a warm vapor cell of enriched 87 Rb without an anti-relaxation coating or a buffer gas, a buffer gas would provide additional tunability due to collisional broadening [23][24][25] . This tunability is ultimately limited to the order of the groundstate hyperfine splitting of the atoms used.…”