Clumping factors of H ii, He ii and He iii

The He ( I ) and He ( II ) Photoelectron Spectra of

U V photoelectron spectra of the title com pounds are rep orted . A ssignm ents are m ade with the help of H e(I)/H e(II) intensity differences, shift effects upon substitu tion and com parison with re la ted m olecules. Previously draw n conclusions about the electronic structure of similar com ­ plexes also hold for the com pounds. It is indicated that the ionization energy for the sym m etri...

Calculations of the binding energies of weakly bound He–He–H, He–He–H− and He–H–H molecules

We searched for the existence of weakly bound He–He–H, He–He–H− and He–H– H molecules where the binding energies are expected to be of the order of degrees Kelvin. By employing the best empirical interaction between each pair of particles, we solved the Schrödinger equation for the triatomic systems using hyperspherical coordinates in the adiabatic approximation. We found no bound states for 4H...

Theoretical calculations of the H I , He I and He II free - bound continuous emission spectra

We present coefficients for the calculation of the continuous emission spectra of H I, He I and He II due to electron-ion recombination. Coefficients are given for photon energies from the first ionization threshold for each ion to the n = 20 threshold of hydrogen (36.5μ), and for temperatures 100 K ≤ T ≤ 10 K. The emission coefficients for He I are derived from accurate ab initio photoionizati...

Patchy intergalactic He ii absorption in HE 2347 − 4342 ⋆

We report on observations of redshifted He ii 303.8 ˚ A absorption in the high-redshift QSO HE 2347−4342 (z = 2.885, V = 16.1) with the Goddard High Resolution Spectrograph on board HST in its low resolution mode (△λ = 0.7 ˚ A). With f λ = 3.6 10 −15 erg cm −2 s −1Å −1 at the expected position of He ii 304Å absorption it is the most UV-bright high redshift QSO discovered so far. We show that th...

Autoionization of He and Autodetachment of He- following Bombardment by H+, H2+, He+, and He Atoms