ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The surface reaction of molecular or atomic fluorine beams with single crystal Cu(111) and polycrystalline copper surfaces has been studied at surface temperatures between 760 and 1050 K using laser-induced fluorescence spectroscopy (LIF), Auger electron spectroscopy (AES), and mass spectrometry. Thereby the fluorination of a hot copper sample was found to be an efficient mode of preparing a clean surface as proven by AES. At low surface temperatures CuF and CuF2, as well as Cu3F3 and Cu4F4 clusters are products of the dry etching reaction, desorbing into the gas phase. At high temperatures copper monofluoride, CuF in the X 1Σ+ electronic ground state is the dominant product. The kinetics of CuF desorption has been studied under steady-state conditions as a function of fluorine flux and surface temperature using the LIF approach. These parametric measurements can be fitted to an apparent activation energy, Ea=157±7 kJ mol−1. Further, it was possible to measure the time-resolved CuF desorption. The LIF signal is comprised of a first- and zeroth-order contribution. The observation of the zeroth-order component can be seen as an indication of the formation of fluorinated copper layers which are responsible for the (CuF)n (n=3,4) cluster formation. From the first-order decay the Arrhenius parameters Ea=167±6 kJ mol−1 and A=1011.0±0.4 s−1 are derived. Both values for Ea derived in this study are in reasonable agreement though the latter value is regarded to be more significant. The Arrhenius parameters reflect themselves in a long residual lifetime of CuF molecules once they are formed at the surface in the order of milliseconds at surface temperatures of 1000 K. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469433
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