Knowledge Bank

The temperature dependence of $N2$-broadened halfwidths of water was studied for rotational vibrational transitions of atmospheric importance. The halfwidths were calculated using cutoff free $theory1$ with Anderson-Tsao-$Curnutte2$ interruption functions and trajectories correct to first-order-in-$time3$. The calculations were carried out for pure rotational transitions and for $\nu 2$ transitions. The temperture dependence was calculated assuming the exponential form $\gamma (T0)-\gamma (T)\{TT0\}n$ The exponent n has been calculated for different rovibrtional transitions and the calculations have been performed over the temperature range 200 K to 1000 K to be applicable to both atmospheric studies as well as hot sources. The trends in $\pi$, such as vibrational dependence, J dependence, etc., are examined and recommended values are given.