Sublimation of low-temperature matrices containing a vibrationally excited component

A dual mass spectrometer was used to investigate the sublimation of solid Ar–SF₆ mixtures exposed to CO₂ laser radiation (τ ~0.2 µsec, Φ ~0.1 J/cm², T₀ = 8–20 K). Under conditions of resonant vibrational excitation of the molecular impurity, the only observed sublimation product was argon. The dependence of the argon yield on the laser radiation energy was consistent with the activation law although, when the frequency departed from resonance, not only the exponential term but also, which was particularly important, the preexponential factor decreased. Hence, under the conditions studied, the evaporation process was essentially non thermal. It may be postulated that elementary events involving direct transfer of the intramolecular vibration energy to the translational degrees of freedom of the emitted particles play an important role in this process.