Abstract
When hydrocarbon molecules come in contact with a tungsten emitter held at a high tempera-ture, 1260°K, they dissociate and liberate carbon atoms s which stick on the emitter surface, thus resulting in a particular emission pattern with dark (334) planes. The appearance of these (334)s is followed by a sharp increase of emission current, and by measuring the time taken for this increase to begin, one can detect the amount of the vapor. In the present work, the detection sensitivity of hydrocarbon vapor is measured by introduction of known amount of diffusion pump oil vapor C10H7C16H33 or propane C3H8, and, with the oil vapor and propane, the vapor pressures of the order of 10-10 Torr and 10-9 Torr respectively can be detected in about 10 minutes.
