Measurements Of Pressure-broadening And Frequency-shifts Of HD Rotational Transitions For Jovian Atmospheres

We have measured spectroscopy of hydrogen deuteride (HD) for pure rotational transitions, R(0)-R(3), in the 85-360 cm^-1 region. D/H ratios are crucial indicators of planetary formation and evolution, and they are most directly obtained from the relative abundance in the HD and H2 measurements. For HD pure rotational transitions, the HITRAN 2016 database has adopted a value of 0.05 cm^-1/atm for self- and H₂-width by default, which, however, seem to be overestimated approximately by a factor of five when they are compared to laboratory measurements. The laboratory study from this work has confirmed that the HITRAN default values are indeed overestimated. Since the pressure broadening parameters are substantially coupled to line intensities, all the spectroscopic parameters (such as position, intensity, linewidth, and pressure shift) are best retrieved simultaneously. We have obtained new high resolution (e.g., 0.0007 cm^-1) spectra at temperatures between 100–296 K at Synchrotron Soleil, France. We have determined their spectroscopic line parameters and their temperature dependences, including the collisional narrowing coefficients through a state-of-the-art multi-spectrum fitting algorithm adopting non-Voigt line shape profile. We will present new results and compare them with previous work and the parameters listed in HITRAN. The new measurements support various NASA space telescope missions, such as ISO, Spitzer, Herschel/PACS, upcoming JWST, and future FIR space telescopes (e.g., Origins).