While investigating density transformation of middle-IR and far-IR spectra of hydrogen fluoride-xenon gas phase mixture, we discovered the xenon-broadened HF vibrational- rotational lines in the band 1 - 0 to be distinctly asymmetrical, and their broadening coefficients to be the greater in comparison with pure rotational ones the greater J-values are. Previously, the similar effect was observed for argon broadened HF lines. It is collisional perturbation of vibrational motion whose influence on line shape formation is essential in these cases. To reconstruct vibrational line shape, i.e., to characterize vibrationally excited molecular dynamics in dense media, it is necessary to obtain rather accurate absorption data concerning pure rotational line shapes. Recently we have determined pure rotational line shape parameters of xenon-broadened HF lines. Symmetrical Lorentz line shape was assumed because no experimental evidence for asymmetry of pure rotational lineshapes has been obtained. Later we found in some additional researches the symmetry of pure rotational line shapes of hydrogen fluoride broadened by xenon and nitrogen in gas phase at room temperature.