Combet-Farnoux minimum

The possibility of such minima in the observed cross section, and the explanation of how they arise were first discussed by Rudkjpbing [138], in a pioneering paper which is unfortunately hard to find and has therefore been rarefy quoted. Accurate calculations of cross sections near such minima in the alkalis were first reported by Seaton [139]. Similar calculations were also performed by Cooper [140]. In line with current usage, we shall refer to such features as Seaton-Cooper minima. They are not to be confused with another type of minimum of the photoionisation cross section (the Combet-Farnoux minimum), which occurs in the presence of a centrifugal barrier (see section 5.4). 

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