Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experimental observation of the elusive double-peak structure in
  R-dependent strong-field ionization rate of H2+   When a diatomic molecule is ionized by an intense laser field, the ionization
rate depends very strongly on the inter-nuclear separation. That dependence
exhibits a pronounced maximum at the inter-nuclear separation known as the
critical distance. This phenomenon was first demonstrated theoretically in H2+
and became known as charge-resonance enhanced ionization (CREI, in reference to
a proposed physical mechanism) or simply enhanced ionisation (EI). All
theoretical models of this phenomenon predict a double-peak structure in the
R-dependent ionization rate of H2+. However, such double-peak structure has
never been observed experimentally. It was even suggested that it is impossible
to observe due to fast motion of the nuclear wavepackets. Here we report a
few-cycle pump-probe experiment which clearly resolves that elusive double-peak
structure. In the experiment, an expanding H2+ ion produced by an intense pump
pulse is probed by a much weaker probe pulse. The predicted double-peak
structure is clearly seen in delay-dependent kinetic energy spectra of protons
when pump and probe pulses are polarized parallel to each other. No structure
is seen when the probe is polarized perpendicular to the pump.

12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex