The above approach for the estimation of the ion yields of different classes of compounds is at the macroscale level based on gas phase thermal equilibrium. A different approach for the analysis is to analyze at the individual ion pair level. This approach may be more likely to foster insights useful for the design of experiments to improve the sensitivity and resolution of MALDI MS. At the time of ion extraction, the ion pair thermal model assumes that the plume is overall neutral, all ions are ion paired, and the relative ratios of different species have already been set by thermal equilibrium at a certain stage of the desorption and ionization process when the plum was at certain temperature and pressure. Later in the process when the pressure is lowered, new equilibrium cannot be formed. The ion pairs (as well as neutral molecules) have different energies. For a small fraction (see the following for specifics) of the ion pairs (or molecules with ion pairs), their energy is significantly higher than the average. Upon application of the ion extraction potential, the ion pairs with much higher energy are permanently separated. The separated ions go in opposite directions and become free ions. An ion may collide with another ion pair or neutral molecule before entering the field free region of the spectrometer, but this does not necessarily consume the free ion. The free ion may continue to travel to the detector, or it may pair or react with the oppositely charged ion in the ion pair and the other ion in the ion pair may reach the detector.