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 = 7(2.5) <- 8(1.8) (1.147THz), 8(5.4) <- 7(6.1) (1.168THz), 7(4.4) <- 6(5.1) (1.173THZ), 8(5.3) <- 7(6.2) (1.191 THz), and 6(3.3) <- 5(4.2) (1.542THz) 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. (c) 2008 Elsevier Ltd. All rights reserved.