Pressure-broadening of water lines in the THz frequency region: Improvements and confirmations for spectroscopic databases.: Part I

The self-, nitrogen- and oxygen-broadening of the J=72,5←81,8 (1.147 THz), 85,4←76,1 (1.168 THz), 74,4←65,1 (1.173 THz), 85,3←76,2 (1.191 THz), and 63,3←54,2 (1.542 THz) rotational transitions of water vapor have been experimentally and theoretically investigated in the present work, showing that the corresponding HITRAN self-broadening parameters are affected by large errors. Indeed, simple semiclassical calculations performed for more than 1500 rotational water lines with wavenumber below 1000cm-1 allow us to improve the self-broadening values reported in the HITRAN database when obtained by assuming a J dependence. On the other hand, our measurements and calculations confirm the values reported in the HITRAN database for air-broadening and shift, which are based on semiclassical computations as well. On the whole, the present investigation provides new experimental as well as theoretically improved values for self-broadening parameters of rotational lines in the THz frequency region.