Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The electron affinity of astatine   One of the most important properties influencing the chemical behavior of an
element is the energy released with the addition of an extra electron to the
neutral atom, referred to as the electron affinity (EA). Among the remaining
elements with unknown EA is astatine, the purely radioactive element 85.
Astatine is the heaviest naturally occurring halogen and its isotope $^{211}$At
is remarkably well suited for targeted radionuclide therapy of cancer. With the
At$^-$ anion being involved in many aspects of current astatine labelling
protocols, the knowledge of the electron affinity of this element is of prime
importance. In addition, the EA can be used to deduce other concepts such as
the electronegativity, thereby further improving the understanding of
astatine's chemistry. Here, we report the first measurement of the EA for
astatine to be 2.41578(7)eV. This result is compared to state-of-the-art
relativistic quantum mechanical calculations, which require incorporation of
the electron-electron correlation effects on the highest possible level. The
developed technique of laser-photodetachment spectroscopy of radioisotopes
opens the path for future EA measurements of other radioelements such as
polonium, and eventually super-heavy elements, which are produced at a
one-atom-at-a-time rate.

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The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga