Photodissociation and photoionisation of atoms and molecules of astrophysical interest

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Volume 602 (June 2017)

A&A, 602 (2017) A105

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Table 22

Photodissociation branching of H₂O and NH₃.

Radiation field^a	Rate^b	Frac.^c	Unc.^d	Rate	Frac.	Unc.
	H₂O → OH + H			H₂O → O + 2H/H₂

ISRF	5.9×10	0.77	B	1.8×10	0.23	B
Mathis ’83	4.0×10	0.75	B	1.3×10	0.25	B
Black Body 4000 K	1.6×10	0.99	A	2.3×10	0.01	C
Black Body 10 000 K	4.4×10	0.93	A	3.3×10	0.07	B
Lyman-α	1.8×10	0.74	A	6.2×10	0.26	A
Solar	2.0×10	0.88	A	2.7×10	0.12	B
TW-Hydra	1.2×10	0.76	A	4.0×10	0.24	A
Cosmic-ray induced	7.6×10	0.77	B	2.2×10	0.23	B

	NH₃→ NH₂ + H			NH₃→ NH + 2H/H₂

ISRF	8.3×10	0.58	B	6.1×10	0.42	B
Mathis ’83	5.6×10	0.57	B	4.3×10	0.43	B
Black Body 4000 K	3.6×10	1.00	A	2.3×10	0.00	C
Black Body 10 000 K	1.6×10	0.95	A	9.0×10	0.05	B
Lyman-α	6.6×10	0.05	B	1.3×10	0.95	A
Solar	4.0×10	0.99	A	5.6×10	0.01	C
TW-Hydra	4.9×10	0.35	A	9.1×10	0.65	A
Cosmic-ray induced	3.9×10	0.39	B	6.2×10	0.61	B

Notes.

^(a)

Radiation fields are defined and normalised as for Tables 18 and 20.

^(b)

In units of s^-1.

^(c)

Estimated branching fraction between all channels producing OH and O (or NH₂ and NH) regardless of excitation state or the chemical co-fragment.

^(d)

Estimated rate uncertainties: accurate to within 30% (A), a factor of 2 (B), a factor of 10 (C).

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