Method for the measurement of diffusion coefficients of labile gas-phase species: The diffusion coefficient of O(3P) in He at 294 K

✍ Scribed by I. C. Plumb; K. R. Ryan; N. G. Barton

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 727 KB
• Volume: 15
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550151012

✦ Synopsis

The dispersion of a pulse of O(3P) atoms in flowing helium has been analyzed by a modification of Taylor's method in order to determine the diffusion coefficient. Atoms of O(3P) were produced in a flowing stream of helium by a pulsed microwave discharge of molecular oxygen. After traversing a known length of the flow tube, the arrival time distribution of the O(3P) atoms was obtained using a mass spectrometer. The value obtained for DO a t 294 K, where DO = D[He], is (2.40 f 0.06) X 1019 cm-l. s-l, which corresponds to a diffusion coefficient of (731 f 18) cm% at 1 torr. In addition to Do, analysis of the arrival time distributions gives an estimate of the mean flow velocity for 0 atoms in helium. There was no significant difference between the value of the velocity found this way and that obtained from the mean bulk gas flow measurement. Thus for this system there is no evidence for a chromatographic effect for O(3P) atoms on the walls of the flow tube.