Radiative Transitions between the ${4D^{10}5p^2(^3P_j)nl}$ and ${4D^{10}5s5p(^3P_1^o)nl}$ Autoionizing States of in Atom in Collisions of Slow Electrons with in$^{+}$ Ions
The radiative transitions between the $4d^{10}5p^2(^3P_{0,1,2})nl$ and {$4d^{10}5s5p({}^3P_1^o)nl$ autoionizing} states of an indium atom that represent dielectronic satellites of the $4d^{10}5p^2 {}^3P_0 \to 4d^{10}5s5p {}^3P_1$ ($\lambda =171.7$ nm), $4d^{10}5p^2 {}^3P_1 \to 4d^{10}5s5p {}^3P_1$ ($\lambda =166.7$ nm), and $4d^{10}5p^2 {}^3P_2 \to 4d^{10}5s5p {}^3P_1$ ($\lambda =160.7$ nm) spectral lines of an In$^{+}$ ion have been observed for the first time. The energy dependences of the effective excitation cross sections of dielectronic satellites, as well as near-threshold regions of these spectral lines, were investigated in the range of electron energies 9$\div $15 eV with the help of the spectroscopic method using crossed beams of electrons and In$^{+}$ ions. The absolute excitation cross sections of dielectronic satellites amount to $(0.7\div 2)\times 10^{-16}$ cm$^{2}$ and are of the same order of magnitude as the effective excitation cross sections of the corresponding ionic lines. It is found that a considerable increase of the probability of radiation decay of the $4d^{10}5p^2(^3P_{0,1,2})nl$ autoionizing states of the In atom is related to strong relativistic and correlation effects, in particular to the configuration interaction of the $5p^2nl$ levels both with one another and with the levels of the $5s5dnl$ and $4d^95s^25p^2$ configurations.