Vaporization of alkali halides

There are monomers, dimers and sometimes trimers in the vapors of alkali halides. It can be shown that Eq. (22) is valid not only for the total pressure but also for the partial pressures of each species. 

It is now a well-recognized fact that the saturated vapors of alkali halides contain associated species (dimers, trimers, etc.) as well as the diatomic molecules. The first evidence of this behavior was an electron-Impact mass spectrometrlc study by Ionov (] ). He reported the observation of K2I and Na2l" , which he attributed to the process... 

---