Detection of trielectronic recombination of In$^+$ ion

The trielectronic recombination of an In$^{+}$ ($4d^{10}5s^2{\,}^1S_0$) ion in collisions with slow electrons, including the two-electron excitation of the $5s^{2}$ core of the ion with the simultaneous capture of the triply excited $5p^{3}$ intermediate autoionizing state with its subsequent radiative stabilization $5p^{3} \to 5s5p^{2}+h\nu$ has been detected and experimentally examined for the first time. The maximum effective cross section of trielectronic recombination is $1.6\cdot 10^{-16}$ см$^{2}$, which is comparable to the effective cross sections for both dielectronic recombination and electron excitation of the In$^{+}$ ion.