Other plating techniques include electroplating, vapor deposition under vacuum and sputter deposition. After cleaning, metals are deposited via sputter deposition, evaporation or chemical vapor deposition (CVD). Often used is electron beam evaporation, or a range of sputter deposition techniques. The sputter gas is typically an inert gas such as argon. Argon is preferred for the sputter coating of specimens for scanning electron microscopy. Its monocrystals can be used as optical windows and high-quality sputter deposition targets. Reactive gases can also be used to sputter compounds. When the high-energy gallium ions strike the sample, they will sputter atoms from the surface. They collide with it and sputter it off, exposing the substrate to the chemical etchant. The car would sputter and backfire as Jacobs tried to move it closer. Sputter deposited films have a composition close to that of the source material. The particles sputter off material from the surfaces and create chemical changes via radiolysis. An automobile engine that is dieseling will typically sputter, then gradually stop. The processes affecting these are sputter and ablation of the inner wall. In the first half both teams would sputter offensively.