Thermioinc Emission From Platinum in Hydrocarbon Flows at Low Pressure

Journal Article

Halpern,B, . 1981

• نوع عمل المنشور: PhD
• المجلة \ الصحيفة: J. Applied Physics
• رقم الإصدار السنوي: 52
• الصفحات: 5315

مستخلص المنشور

A novel "chopped fast flow" technique for surface reac tion studies is described. It extend s the 
molecular beam chopping approach to fast flow systems, exploits higher reac tant and produc t 
fluxes, and permits transient rate measurements of fast surface reac tions at much higher pressure. 
 It employs an oscillating needle gas source to generate reactant square wave flows.
The method was used to measure rates of carbon deposition following impact of hydrocarbon molecules 
on a hot Pt surface (T > 1000 °K). Square wave flows of hydrocarbon and oxygen, out of phase• 
produced period changes in carbon coverage, surface work function, and thermionic
electron emission current. Carbon deposition races were inferred from the variation of emission 
current with time. Deposition probabilities were low and very sensitive to hydrocarbon chain 
length. The results suggest that energy transfer during the short physisorption lifetime of the 
hydrocarbon molecule limits the deposition probability.