Surface diffusion measurements by digitized autocorrelation of field emission current fluctuations
作者:
J. E. Whitten,
R. Gomer,
期刊:
Review of Scientific Instruments
(AIP Available online 1994)
卷期:
Volume 65,
issue 12
页码: 3707-3717
ISSN:0034-6748
年代: 1994
DOI:10.1063/1.1144496
出版商: AIP
数据来源: AIP
摘要:
The operating criteria of analog and digital methods for obtaining field emission fluctuation autocorrelation functions for the determination of surface diffusion coefficients are discussed and the strengths and limitations of both methods pointed out. Two digital systems, one using a spiraltron for pulse counting, the other a fast phosphor‐photomultiplier combination for the same purpose, are described and test results presented. Some results obtained digitally for W self‐diffusion on W(123) and for oxygen diffusion on W(110) are presented and shown to agree with previous results obtained by the analog method. To illustrate the potential of the digital method for obtaining very smallDvalues results for the diffusion of H on Re(112¯0) at 80 K are also presented. For this case &tgr;0=13 s, andD=1×10−14cm2 s−1. ©1994 American Institute of Physics.
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