Field ionization process of Eu 4f<sup>7</sup>6s<em> n</em>p Rydberg states<xref ref-type="fn" rid="cpb150726fn1">*</xref>

Field ionization process of Eu 4f⁷6s np Rydberg states*

Zhang Jing^a),^b), Shen Li^a),^b), Dai Chang-Jian^a),^b)

The diagram of the experimental scheme.