Comments: The Verner+1996 cross sections include contributions by all shells. In the code this total cross section is treated as the valence electron cross section (and other cross sections are put to zero). It is also assumed that all transitions occur to the ground state of the ion. The cross section is ascribed to all substates in the ground multiplet.

For nebular phase, only photoionizations from the ground state and meta-stable states play any role: for higher states a rough approximation like the hydrogen one is sufficient. The hydrogen approximation used is fully described in J12. Note that even if the first excited state is connected to the GS by an allowed transition, it is effectively metastable due to photon trapping - detailed cross sections for all first or even second excited states are desirable. I mark these as (E), with (T) meaning truly metastable.

TOPBASE photoionisation cross sections unfortunately come without any specific paper references. Presumably the calculations are fully specified by the TOPBASE method paper Cunto W., Mendoza C., Ochsenbein F., Zeippen C.J., 1993, A&A 275, L5.

In SUMO only the three first ionization stages are included, so photoionisation data for the neutrals and singly ionised are needed.

Note that stimulated recombination is ignored in SUMO.

HI (Latest doc J11):

GS : Verner et al. 1996
Meta-stable :
n=2 (E) : Bethe & Salpeter 1957 (incorrect reference to TOPBASE in J11)
Rest up to 50 : Hydrogenic
HeI (Latest doc J11):

GS : Verner et al. 1996
Meta-stable :
3S (T) : TOPBASE
1S (T) : Hydrogenic
Rest up to 50 : Hydrogenic
HeII (Latest doc J11):

GS : Verner et al. 1996
Rest up to 50 : Hydrogenic
CI (Latest doc J11):

GS : Verner et al. 1996
Metastable:
1D (T) : TOPBASE (Marked out)
1S (T) : TOPBASE (Marked out)
5S (T) : TOPBASE (Marked out)
Rest up to 50 : Hydrogenic
CII (Latest doc J11):

GS : Verner et al. 1996
Metastable:
4P (T) : Hydrogenic
Rest up to 50 : Hydrogenic
NI (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2D (T) : TOPBASE
2P (T) : Hydrogenic
4P (E) : Hydrogenic
Rest up to 50 : Hydrogenic
NII (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2D (T) : Hydrogenic
2S (T) : Hydrogenic
Rest up to 50 : Hydrogenic
OI (Latest doc J11):

GS (<912 A) : Verner et al. 1996
Metastable:
1D, <1064 A (T) : 0 (forbidden)
1S, <1315 A (T) : 0 (forbidden)
5S, <2772 A (T) : TOPBASE, presumably Nahar+1998
Rest up to 50 : Hydrogenic
OII (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2D (T) : Hydrogenic
2P (T) : Hydrogenic
4P (T) : Hydrogenic
Rest up to 50 : Hydrogenic
NeI (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2[3/2], < 2506/2533 A (E) : Hydrogenic
2[1/2], < 2556/2608 A (E) : Hydrogenic
Rest up to 50 : Hydrogenic
NeII (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2S (E) : Hydrogenic
Comments : 2-level atom
NaI (Latest doc J11):

GS : Verner et al. 1996
Metastable:
2P (E) : Hydrogenic
Rest up to 50 : Hydrogen
MgI (Latest doc J11):

GS : Verner et al. 1996 (valence shell only)
Metastable:
s3p(3P) : TOPBASE
s3P(1P) : TOPBASE
s4s(3S) : TOPBASE
Rest up to 50 : Hydrogen
MgII (Latest doc J11):

GS : Verner et al. 1996
Metastable: 3p(2P*) : TOPBASE
Rest : Hydrogenic
SiI

GS, 1520 A : Verner et al. 1996
Metastable:
3p2(1D), < 1680 A : Hydrogenic
3p2(1S), < 1985 A : Hydrogenic
3p3(5S), < 3084 A : Hydrogenic
Rest up to 50 : Hydrogen
SiII

GS, <758 A : Verner et al. 1996
Metastable:
3-5, 3p2(P4) (T), < 1120 A : Hydrogenic
6-7, 3p2(2D) (E), < 1306 A : Hydrogenic
8, 4s(2S) (E) < 1506 A : Hydrogenic
9, 3p2(2S) (E) < 1811 A : Hydrogenic
10-11 3d(2D) (E), < 1903 A : Hydrogenic
Rest up to 50 : Hydrogen
SI

GS : Verner et al. 1996
Metastable:
3p4(1D):TOPBASE
3p4(1S): Hydrogenic
Rest up to 50 : hydrogenic
SII

GS : Verner et al. 1996
Metastable:
3p3(2D*) : Hydrogenic
3p3(2P*) : Hydrogenic
Rest up to 50 : Hydrogenic
ArI & II Verner for GS, hydrogenic for excited.

CaI

GS : Verner et al. 1996
Metastable: None
Rest up to 50 : Hydrogenic
CaII

Sc-Mn Verner+1996 for GS, hydrogenic all excited.

FeI (Latest doc J11).

GS : Verner et al. 1996
Metastable:
Levels up to 55 (4s b3H) have small or moderate A-values.
First excited (a5F) : Nahar online, rest hydrogenic.
FeII (Latest doc J11).

GS : Verner et al. 1996
Metastable :
Allow transitions start from level 64, so 1-63 can behave as metastable.
First excited (a4F) : Nahar & Pradhan 1994 via Nahar online (J11). Note erroneous reference to TOPBASE in J11.
Others up to 50 : Hydrogenic.
CoI

GS : Verner et al. 1996
Metastable:
First 30 excited states meta-stable : Hydrogenic
Rest up to 50 : Hydrogenic
CoII

GS : Verner et al. 1996
Metastable:
First 30 excited states meta-stable : Hydrogenic
Rest up to 50 : Hydrogenic
NiI

GS : Vernet et al. 1996
Metastable:
First 13 excited states meta-stable : Hydrogenic
Rest up to 50 : Hydrogenic
NiII (Latest doc J11):

GS : Verner et al. 1996
Metastable:
First 16 excited states meta-stable : Hydrogenic
Rest up to 50 : Hydrogenic