Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic excitations and the tunneling spectra of metallic nanograins   Tunneling-induced electronic excitations in a metallic nanograin are
classified in terms of {\em generations}: subspaces of excitations containing a
specific number of electron-hole pairs. This yields a hierarchy of populated
excited states of the nanograin that strongly depends on (a) the available
electronic energy levels; and (b) the ratio between the electronic relaxation
rate within the nano-grain and the bottleneck rate for tunneling transitions.
To study the response of the electronic energy level structure of the nanograin
to the excitations, and its signature in the tunneling spectrum, we propose a
microscopic mean-field theory. Two main features emerge when considering an Al
nanograin coated with Al oxide: (i) The electronic energy response fluctuates
strongly in the presence of disorder, from level to level and excitation to
excitation. Such fluctuations produce a dramatic sample dependence of the
tunneling spectra. On the other hand, for excitations that are energetically
accessible at low applied bias voltages, the magnitude of the response,
reflected in the renormalization of the single-electron energy levels, is
smaller than the average spacing between energy levels. (ii) If the tunneling
and electronic relaxation time scales are such as to admit a significant
non-equilibrium population of the excited nanoparticle states, it should be
possible to realize much higher spectral densities of resonances than have been
observed to date in such devices. These resonances arise from tunneling into
ground-state and excited electronic energy levels, as well as from charge
fluctuations present during tunneling.

28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio