Electron-impact excitation of the In+ ion resonance line

Full text: Study of the electron-impact excitation of the In+ ion is important not only for atomic structure research, but also for applications to astrophysics, analytical techniques and fusion research, as well as for new applications of this ion such as a component of solid state laser media and as a source for an optical frequency standart. The energy dependence of the electron-impact excitation of the In+ ion resonance line was studied by spectroscopic method using the crossed-beam technique in the energy range from the threshold up to 300 eV for the following process: e + In+(4d105s2) 1S0 e' + In+(4d105s5p) 1P01 e' + In+(4d105s2) 1S0 +h (1) Process (1) includes the direct electron-impact excitation of the 5s5p 1P01 state from the ground 5s21S0 state, as well as the contribution of the cascade transitions and resonance processes: In+(4d105s nln1l1, 4d105p2nl, 4d95s2 nln1l1) In+(4d105s2) 1S0 + e' (2) The peculiarity of this investigation is the presence of low lying metastable states and high temperature (T1250K) of atomic vapour. The ions produced in the ion source on the heated tantalum surface were extracted, focused and accelerated by a system of ion optical lenses into a beam (Ei = 700eV, Ii (11.4)10-6A), separated from neutral atoms by means of a 90 deg electrostatic selector and crossed at the right angle by the ribbon electron beam (Ee = (7300)eV, Ie = (610)10-5A, 01/2 (0.40.5)eV) in the collision region (at P 10-8 Torr) [1]. Radiation observed at 90 deg with respect to the beam intersection plane was spectrally separated by a 70 deg vacuum monochromator (d/dl = 1.7nm/mm) based on the Seya- Namioka scheme and detected by a photomultiplier. The measurements and experimental data processing were realised by means of a PC. The drop of the energy dependence of the excitation cross section obey the E-1 lnE rule specific for the optically allow transitions. A distinct structure in the energy range from the threshold up to 50eV was observed for the first time resulted from the resonance processes due to the formation and subsequent decay of autoionizing states converging to the 4d105snl, 4d105p2 and 4d105s2nl - levels [2] as well as to the cascade transitions from the above levels. The uncertainty of the relative emission cross section was evaluated to be 10 cross sections was about 25 cross section was determined to be 10-16 cm2 at 300eV