Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigation of transient surface electric field induced by femtosecond
  laser irradiation of aluminum   Transient surface electric fields induced by femtosecond laser irradiation of
an aluminum film were investigated directly by ultrashort electron pulses. At
pump intensities of 2.9~7.1 * 10^10 W/cm2, the transient electric fields last
at least one nanosecond with a maximum field strength of 3.2~5.3 * 10^4 V/m at
120 micro m above the aluminum surface. The transient electric fields and the
associated evolution of photoelectrons were explained by a "three-layer" model.
The potential influence of such fields on reflection ultrafast electron
diffraction and time-resolved angle-resolved photoemission spectroscopy were
evaluated.

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The categories of this paper are: hep-ex
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The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
3
The categories of this paper are: physics
2
The categories of this paper are: math