Up: Oscillator strengths for As
Each atom is a manybody system which may be described by an
independentparticlemodel. In this model, each electron moves
independently in an effective potential determined by the nucleus and
the other electrons. The potential for an electron in a neutral or
ionized atom is assumed to have the form

(1) 
where Z is the atomic number, and
is the ionicity:
,
2, 3 for As I, As II, As III, respectively.
The quantity r is the electronnucleus distance, and d, H are
adjustable parameters. The potential of equation (1) is
inserted into the radial Schrödinger equation, which is then
solved to obtain the energy eigenvalues and wave functions. The
parameters d, H are adjusted so as to obtain agreement between the
energy eigenvalues and the experimental singleparticle energy levels.
This procedure and all necessary formulas may be found in a previous
article ([Ganas 1995]). The following values of the potential parameters
were obtained:
d = 1.4196,
H = 8.1745 for As I;
d =
4.7814,
H = 39.726 for As II;
d = 0.6094,
H = 3.0641 for
As III.
Representative energy levels are given in Table 1 for
As III. The computed levels and the experimental levels are in
good agreement, the discrepancy being less than 2% in every case
(except one).
Table 2:
Oscillator strengths, f, for the resonance transition
4p^{3}(^{4}S
)
4p^{2}(^{3}P)5s(^{4}P_{J}) in As I, from the
present calculations, other calculations, and experiment
J 
(Å) 
f (this 
f 
f (other 


calculation) 
(experiment) 
calculations) 
1/2 
1972.6 
0.0532 

0.0584^{d} 



0.074^{b}, 0.0734^{c} 
0.06^{e}, 0.03^{f} 
3/2 
1937.6 
0.1064 

0.113^{d} 



0.14^{b}, 0.139^{c} 
0.11^{e}, 0.06^{f} 
5/2 
1890.4 
0.1596 
0.21^{b}, 0.214^{c} 
0.161^{d}, 0.16^{e} 
 ^{a}
 Bengtsson et al. (1992): uses timeresolved laser spectroscopy.
 ^{b}
 Andersen et al. (1974): uses the beamfoil technique.
 ^{c}
 Lotrian et al. (1980): uses emission spectroscopy.
 ^{d}
 Verner et al. (1994): gives a critical review of fvalues
from previous compilations.
 ^{e}
 Holmgren (1975): uses optimized HartreeFockSlater
local exchange approximation and relativistic wave functions.
 ^{f}
 Lawrence (1967): uses an intermediate coupling theory.
Up: Oscillator strengths for As
Copyright The European Southern Observatory (ESO)