Experimental and theoretical investigation on N2 pressure-induced coefficients of the lowest rotational transitions of HCN

We present the first experimental determination of room-temperature N 2 pressure broadening, speed dependent broadening, and pressure shift coefficients of the three lowest rotational lines of HCN. The experimental results served to assess the accuracy of a low-cost yet accurate computational strategy, which relies on a simplified characterization of the interaction potential, and employs a novel approximate method of solving the quantum scattering problem. Building on the validation of this computational approach, the dataset was extended to higher rotational transitions, up to J ( H C N ) = 5 ← 4 . For these transitions, we provide the temperature dependence of the pressure broadening coefficient, its speed dependence parameter, and the Dicke narrowing parameter. This new dataset will be incorporated into the HITRAN database to support and refine the modeling of HCN in both the terrestrial and Titan’s atmospheres. • First dataset of experimental pressure broadening, speed dependent broadening and pressure shift coefficients for the three lowest rotational transitions of HCN perturbed by N 2 at room temperature. • A novel, computationally feasible, theoretical approach for scattering calculations, and a new HCN-N 2 potential energy surface are validated by comparison with the experimental results. • The first values of N 2 pressure broadening, speed dependent broaden- ing, and Dicke narrowing coefficients computed for the lowest five rota- tional transitions of HCN, together with their temperature-dependence coefficients in the 100 – 800 K temperature range, are presented. • The new dataset refines the values reported in the HITRAN database for the targeted transitions.