Decoupling Multiple Rotational Relaxations of Hydrogen to Detect Gas Mixtures

Decoupling multiple acoustic relaxations in multi-component gas mixtures is an effective method to acquire acoustic relaxation characteristic of gas molecules, which can be used to determine gas composition. However, decoupling multiple rotational relaxations of hydrogen still remains challenge. In this paper, we present the decoupling model of hydrogen and decouple the multiple rotational relaxation into the group of single-relaxation ones. Based on this model, the whole rotational relaxation process of hydrogen can be simplified as a few decoupled single rotational relaxation processes. The decoupled results of the effective specific heat, the absorption spectrum and the acoustic velocity dispersion agree with the experimental data, which validates our decoupling model. Furthermore, the proposed decoupling rotational relaxation model can be combined with the existing decoupling vibration model to detect gas mixture. Applications in the detection of gas mixtures including <inline-formula> <tex-math notation="LaTeX">$N_{2},CO_{2},O_{2}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$H_{2}$ </tex-math></inline-formula> are provided. Compared with existing gas sensing method ignoring rotational relaxation, our detection result of gas mixtures <inline-formula> <tex-math notation="LaTeX">$H_{2}-O_{2}-H_{2}O$ </tex-math></inline-formula> is more convincing since the proposed decoupling model contains significant rotational relaxation of hydrogen. Therefore, the proposed decoupling model not only reveals the mechanism of multiple rotational relaxations of hydrogen, but also provides the new method to detect hydrogen gas mixtures.

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