Three different devices that-can be used for surfac&d~ced d&o&ion (SID) m tandem quadrupole instruments are compared here. The designs were compared by examining the fragmentation of several compounds including benzene, W(CO),, and (CH3)4N+. These studies show that SID can be readily implemented on a variety of tandem quadrupoIe instruments and that the spectra obtained with the in-line and 90" instruments are similar. Evidence is presented that confirms that high average internal energies and narrow distributions of internal energy are available by this technique. Efficiencies for fragmentation of odd-electron ions are on the order of those previously reported by others. The overall SID efficiency for even-electron ions is higher than that for odd-electron ions of similar structure. (J Am Sot Mass Spedrom 2992, 3, 27-32) M ost current applications of tandem mass spectrometry involve collisions of the massselected ions with an inert gas such as He, Ar, or Xc [l]. Recently, Cooks and co-workers [2-41 and others [5-S] have illustrated a variety of interesting processes that occur upon low energy (eV) collisions of mass-selected polyatomic ions with a surface. These include (1) surface-induced dissociation (SID), in which fragmentation is promoted by conversion of some of the kinetic energy of the projectile into inter-na1 energy, (2) reactive collisions of projectile ions with surface adsorbates, and (3) chemical sputtering,l in which the impingement of the projectile ion at the surface causes ejection of secondary ions [2-41. These processes and others are described in more detail in a recent review [3]. Although significant progress has been made in understanding polyatomic ion/surface collisions, this technique is still considered to be a curiosity and is not widely used as an activation method for tandem mass spectrometry experiments.