Electron scattering experiments with hydrogen fluoride-is it really HF?

It is observed that unusually strong desorption effects and chemical reactivity can produce totally spurious results in experiments using hydrogen fluoride gas. It is shown, for example, in the case of electron energy-loss spectra that completely erroneous results are obtained unless adequate sample inlet conditioning is carried out. Comparison of the present experimental work with some literature examples illustrates the need for extreme caution in the interpretation of spectral results when studying hydrogen fluoride. In particular, it is shown that the only published high-resolution electron energy-loss spectrum attributed to HF is in fact due to molecular hydrogen. The high-resolution (0.05 eV FWHM) electron energy-loss spectrum of HF has been measured in the range 12 to 16.5 eV. It is suggested that effects due to desorption by HF are reasonable for the anomalies in published spectra for electron scattering resonances for hydrogen fluoride.