A collisional cooling investigation of the pressure broadening of the 110←101 transition of water from 17 to 200 K

An investigation of the 110←101 rotational transition of water at 556 GHz pressure broadened by hydrogen, helium, nitrogen, oxygen and carbon dioxide has been completed. Using the collisional cooling technique the broadening of this transition by each gas was explored from 200 K down to the condensation point of the broadening gas or 17 K, which ever is lower. This marks the first time such an extensive investigation of the broadening of this rotational transition as a function of temperature has been completed. The results of this investigation will be presented including the exponential temperature dependence of the broadening, the lack of temperature dependence of the broadening observed in helium and the unique behavior of the hydrogen broadening at low temperature (<40 K). In addition, the broadening of the 110←101 rotational transition of water by nitrogen and oxygen was recorded at room temperature and a direct comparison of this data with recent work will be discussed.