Electric-Field-Controlled Rotational Spectroscopy for Highly Selective Gas Sensing

Air quality control is essential for preventing human exposure to toxic and harmful gases and therefore requires reliable and highly selective gas sensors. Over the past few decades, numerous sensing techniques based on different physical and chemical interactions with sensitive materials have been developed. These include optical, calorimetric, acoustic, and electrical sensing methods such as metal-oxide semiconductor sensors. Although significant progress has been achieved in sensitivity-reaching detection limits at the parts-per-billion level-the precise analysis of complex gas mixtures remains a major challenge due to limited selectivity and cross-sensitivity. In this work, we propose a new gas-sensing mechanism based on the interaction of molecular rotational states with a quasistatically swept DC electric field. For molecules possessing permanent electric dipole moments, the presence of a static electric field produces Stark splitting of rotational levels that is characteristic of each molecular species. The proposed scheme enables a single-frequency detector to analyze gas mixtures with high selectivity, accuracy, and sensitivity. The sensing mechanism relies on species-specific Stark interactions and resonant coupling of molecular dipoles to the applied electric field. Preliminary calculations are presented for the molecules H₂O and NH₃, illustrating the feasibility of the method. These results suggest that electric-field-controlled rotational spectroscopy provides a promising pathway toward highly selective gas sensing in complex molecular environments.