This is a complex module containing three different levels of constituent modules. In the first place, this module two components are aggregated: Experimental methods and Theoretical methods.
In the second place, the Theoretical methods in its turn also has two components: one about the transition probability in general and one about the calculation of the differential cross section.
In the third place, that module about the transition probability is a cluster module containing two constituent modules about specific types of transition probabilities. An overview of these constituent modules is given in a brief module summary.
The concepts of this particular reaction studied (differential cross section of chemi-ionization of sodium atoms-iodine atoms), of this particular experimental method used to do so (beam techniques), and of this particular theory (semiclassical model) are included in almost every module in the article, in different combinations and in more or in less detail - in particular in the Central problem and the Situation and in the appropriate (experimental or theoretical) constituent modules of this complex Methods module. However, the actual phrasing of the module summary is ours. It doesn't occur literally in other modules, so that the overlap is kept from getting annoying.