Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

The strong mixing of many-electron basis states in excited atoms and ions with open f shells results in very large numbers of complex, chaotic eigenstates that cannot be computed to any degree of accuracy. Describing the processes which involve such states requires the use of a statistical theory. Electron capture into these “compound resonances” leads to electron-ion recombination rates that are orders of magnitude greater than those of direct, radiative recombination and cannot be described by standard theories of dielectronic recombination. Previous statistical theories considered this as a two-electron capture process which populates a pair of single-particle orbitals, followed by “spreading” of the two-electron states into chaotically mixed eigenstates. This method is similar to a configuration-average approach because it neglects potentially important effects of spectator electrons and conservation of total angular momentum. In this work we develop a statistical theory which considers electron capture into “doorway” states with definite angular momentum obtained by the configuration interaction method. We apply this approach to electron recombination with W²⁰⁺, considering 2×10⁶ doorway states. Despite strong effects from the spectator electrons, we find that the results of the earlier theories largely hold. Finally, we extract the fluorescence yield (the probability of photoemission and hence recombination) by comparison with experiment.

Choreographies of Irish Modernity

Although movement is often viewed as forming the ‘kinetic basis’ of the modern age, the analysis of movement practices such as dance is often neglected in theories of modernity. Dance theorists such as André Lepecki (2006) and Randy Martin (1998) have argued for an awareness of how the kinaesthetic politics of modernity perform a colonization of space and bodies in their constant drive toward movement and mobility. This chapter examines how an analysis of two dance works by Irish artists, one from the early twentieth century and one from the early twenty-first century, can contribute to these discussions of modernity and dance, and how the works might illuminate connections between dance and politics in Ireland in their alternative approaches to these modernist kinaesthetic politics. Taking a brief, contextualizing look at an early dance play by William Butler Yeats, the chapter then focuses on what echoes, or afterlives, can be found from this early modernist work in a piece by contemporary dance theatre choreographer Fearghus Ó’Conchúir. In both works we see the ability of dance to create an alternative space within the pervading discourses (or movements) of a sociopolitical and cultural landscape that allows the spectator – through a visceral connection with a dancer – to experience a different perspective on the ‘idea of a nation’.