On the stark broadening of Ly - α by strong electron collisions

Hubert Capes, Dietrich Voslamber

Dean M. Homan

N. Feautrier, N. Tran Minh

Starting from the exact unified expression of the line profile, a quantum theory is developed making exact allowance for the long-range dipole interaction. The knowledge of the positions of the bound states below the n=2 threshold enables approximation of the contribution of short-range interactions. Good agreement with exact quantum calculations is obtained.

А. П. Коузов

K J Kollath

The nonlinear low-field Stark effect in the level n=2 of hydrogen has been investigated. \nThe experiment employed the level crossing technique, measuring the position of the crossings between the Zeeman states: \n2P3/2, mj=-3/2 and 2P1/2, mj=1/2; and \n2P3/2, mj=-3/2 and 2S1/2, mj=1/2; \nas the electric field was varied from 0 to 500 kV/m. \nA beam of atomic hydrogen, produced by thermal dissociation, was subjected to parallel electric and magnetic fields. Lymman –α (Lyα) resonance radiation was generated in an electrodeless microwave discharge lamp. The profile of the Lyα line emitted by the lamp has been investigated experimentally. \nThe level crossings were detected as changes of the Lyα resonance fluorescence intensity observed in a certain direction. The crossing positions were determined from the observed crossing signals of Lorentzian profile by a least squares computer programme. \nThe experimental results for the crossing positions as afuction of the electric field have been compared with theoretical calculations. The theoretical values were obtained by numerical diagonalization of the matrix of the eigenstates |2ℓjFmF> for perturbation by combined electric and magnetic fields. Radiative corrections were included. \nTheoretical values and experimental results agreo within the experimental uncertainties of 2%.

Ousmanou Motapon, J Picart, N. Tran Minh

We use the global theory of the Stark electronic broadening to calculate the global and wing profiles of the hydrogen Paschen- alpha line. The results obtained for the wings agree with the H beta wings and those for the global profile are in good agreement with the semiclassical theory.