Table B.1: Electronic recombination reactions.
Reaction a b Reference

O²⁺ + e^- $\rightarrow$ O⁺ + $h\nu$ 1.9E-11 -0.65 AP73

C²⁺ + e^- $\rightarrow$ C⁺ + $h\nu$ 2.2E-11 -0.65 AP73

N²⁺ + e^- $\rightarrow$ N⁺ + $h\nu$ 2.1E-11 -0.64 AP73

S²⁺ + e^- $\rightarrow$ S⁺ + $h\nu$ 2.0E-11 -0.69 MHT96

Fe²⁺ + e^- $\rightarrow$ Fe⁺ + $h\nu$ 2.1E-11 -0.84 MHT96

Si²⁺ + e^- $\rightarrow$ Si⁺ + $h\nu$ 1.6E-11 -0.79 MHT96

Mg²⁺ + e^- $\rightarrow$ Mg⁺ + $h\nu$ 1.7E-11 -0.84 AP73

Ne²⁺ + e^- $\rightarrow$ Ne⁺ + $h\nu$ 1.7E-11 -0.69 AP73

Ne⁺ + e^- $\rightarrow$ Ne + $h\nu$ 3.1E-12 -0.76 AP73

Rate coefficients have the form k = a(T/300)^b and a is in units of cm³ s^-1.
AP73 refers to Aldrovandi & Péquignot (1973).
MHT96 refers to Maloney et al. (1996).

**Table B.1:** Electronic recombination reactions.
Reaction	a	b	Reference
O²⁺ + e^- $\rightarrow$ O⁺ + $h\nu$	1.9E-11	-0.65	AP73
C²⁺ + e^- $\rightarrow$ C⁺ + $h\nu$	2.2E-11	-0.65	AP73
N²⁺ + e^- $\rightarrow$ N⁺ + $h\nu$	2.1E-11	-0.64	AP73
S²⁺ + e^- $\rightarrow$ S⁺ + $h\nu$	2.0E-11	-0.69	MHT96
Fe²⁺ + e^- $\rightarrow$ Fe⁺ + $h\nu$	2.1E-11	-0.84	MHT96
Si²⁺ + e^- $\rightarrow$ Si⁺ + $h\nu$	1.6E-11	-0.79	MHT96
Mg²⁺ + e^- $\rightarrow$ Mg⁺ + $h\nu$	1.7E-11	-0.84	AP73
Ne²⁺ + e^- $\rightarrow$ Ne⁺ + $h\nu$	1.7E-11	-0.69	AP73
Ne⁺ + e^- $\rightarrow$ Ne + $h\nu$	3.1E-12	-0.76	AP73

Source LaTeX | All tables | In the text

	1 Introduction
	2 Model
	3 X-ray induced chemistry
	4 Results and discussion
	5 X-ray tracers
	6 AFGL 2591 models
	7 Calculated emission lines
	8 Conclusion
	References
	Online Material
	Appendix A: Initial chemical abundances
	Appendix B: Electron recombination and charge transfer reactions
	Appendix C: Influence of $T{_{{\rm X}}}$ and $N{_{{\rm H,in}}}$
	Appendix D: Influence of an outer FUV field and cosmic rays
	Appendix E: Comparison to observations