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 1

Some summary properties of atomic and molecular cross sections.

	Thresh.	Threshold (nm)^b		Ly-α cross section (cm²)^c		Uncertainty^d		References^e
Species	Dissoc. prod.^a	Dissoc.	Ionis.	Dissoc.	Ionis.	ISRF	Ly-α	Cross sec./Dissoc. threshold/Ionis. threshold

H	–	–	91.2	0	0	A	–	Sect. 4.3.1/–/Kelly (1987a)
Li	–	–	230	0	1.33×10	A	A	Huebner & Mukherjee (2015)/–/Kelly (1987a)
C	–	–	110	0	0	B	–	Sect. 4.3.2/–/Kelly (1987a)
N	–	–	85	0	0	A	–	Sect. 4.3.3/–/Kelly (1987a)
O	–	–	91.04	0	0	B	–	Sect. 4.3.4/–/Kelly (1987a)
Na	–	–	241	0	1.07×10	B	B	Huebner & Mukherjee (2015)/–/Kelly (1987a)
Mg	–	–	162	0	7.13×10	B	B	Sect. 4.3.5/–/Kelly (1987a)
Al	–	–	207	0	8.71×10	B	B	Sect. 4.3.6/–/Kelly (1987a)
Si	–	–	152	0	3.61×10	B	B	Sect. 4.3.7/–/Kelly (1987a)
P	–	–	118	0	0	C	–	Sect. 4.3.8/–/Kelly (1987a)
S	–	–	120	0	0	A	–	Sect. 4.3.9/–/Kelly (1987a)
Cl	–	–	96	0	0	B	–	Sect. 4.3.10/–/Kelly (1987a)
K	–	–	286	0	2.22×10	B	B	Sect. 4.3.11/–/Kelly (1987a)
Ca	–	–	203	0	9.13×10	B	B	Sect. 4.3.12/–/Kelly (1987a)
Ti	–	–	182	0	5.72×10	C	C	Reilman & Manson (1979) /–/Sohl et al. (1990)
Cr	–	–	183	0	7.35×10	B	B	Reilman & Manson (1979) /–/ Kelly (1987a)
Mn	–	–	167	0	4.42×10	B	B	{ (Reilman & Manson 1979; McGuire 1968)/–/ Kelly (1987b)
Fe	–	–	158	0	4.86×10	A	A	Sect. 4.3.13/–/Kelly (1987b)
Co	–	–	158	0	1.77×10	B	B	Reilman & Manson (1979) /–/Kelly (1987a)
Ni	–	–	162	0	3.12×10	B	B	van Dishoeck (1988)/–/Kelly (1987b)
Zn	–	–	132	0	5.91×10	B	B	Sect. 4.3.14/–/Kelly (1987b)
Rb	–	–	297	0	1.49×10	B	B	{(Weisheit 1972; Suemitsu & Samson 1983)/–/ (Sansonetti 2006)
Ca⁺	–	–	104	0	0	B	–	Black et al. (1972) /–/Kelly (1987a)
H⁻	–	–	1470	0	4.75×10	B	B	Wishart (1979) /–/Kinghorn & Adamowicz (1997)
H₂	H + H	274	82	0	0	A+	–	{ Sect. 4.3.15/Huber & Herzberg (1979)/ Wolniewicz (1995)
H	H + H⁺	290	–	6.83×10	0	A	A	Dunn (1968) /Babb (2015) /–
H	H⁺ + H₂	283	–	0	0	A	–	Kulander & Bottcher (1978)/Cosby & Helm (1988) /–
CH	C + H	358	117	5.00×10	0	C	C	{ van Dishoeck (1987) /Huber & Herzberg (1979)/ Huber & Herzberg (1979)
CH⁺	C + H⁺	303	–	5.00×10	0	A	C	Kirby et al. (1980), Uzer & Dalgarno (1978)/Huber & Herzberg (1979) /–
CH₂	CH + H	417	119	5.00×10	0	C	C	{van Dishoeck et al. (1996), Kroes et al. (1997)/ Kroes et al. (1997)/ Herzberg (1966)
CH	CH⁺ + H	204	–	5.00×10	0	B	C	Sect. 4.3.17/Vane et al. (2007) /–
CH₃	CH + H₂	271	126	5.00×10	5.31×10	B	B	Sect. 4.3.18/Yu et al. (1984)/Schulenburg et al. (2006)
CH₄	CH₃ + H	277	98	1.80×10	0	A+	A+	Sect. 4.3.19/Gans et al. (2011)/Sorensen et al. (1995)
CH	CH + H	1031	–	5.00×10	0	B	C	Sect. 4.3.20/van Dishoeck et al. (1980)/–
C₂	C + C	193	102	4.98×10	0	B	B	{ Pouilly et al. (1983) /Feller & Sordo (2000)/ Huber & Herzberg (1979)
C₂H	C₂ + H	253	109	3.21×10	0	B	C	{ Sect. 4.3.21/van Hemert & van Dishoeck (2008)/ van Hemert & van Dishoeck (2008)
C₂H₂	C₂H + H	217	109	5.78×10	0	A+	B	Sect. 4.3.22/Wu et al. (2010) /Metzger & Cook (1964)
C₂H₄	C₂H₂ + H₂	258	118	2.36×10	0	C	C	{ Zelikoff & Watanabe (1953) /Petrank et al. (1992)/ Knowles & Nicholson (1974)
C₂H₆	C₂H₅ + H	287	108	2.26×10	0	A+	A+	{ Sect. 4.3.23/Bauschlicher & Partridge (1995)/ Chupka & Berkowitz (1967)
C₃	C₂ + C	268	102	1.38×10	0	C	C	Sect. 4.3.24/Kim et al. (1997) /Benedikt et al. (2005)
l-C₃H	C₃ + H	379	144	5.00×10	0	B	C	{ Sect. 4.3.25/van Hemert & van Dishoeck (2008)/ van Hemert & van Dishoeck (2008)
c-C₃H	C₃ + H	289	129	5.00×10	0	B	C	{ Sect. 4.3.26/van Hemert & van Dishoeck (2008)/ van Hemert & van Dishoeck (2008)
HC₃H	l-C₃H + H	400	138	5.00×10	0	B	C	Sect. 4.3.27/Mebel et al. (1998) /Taatjes et al. (2005)
l-C₃H₂	l- C₃H + H	320	119	5.00×10	0	B	C	Sect. 4.3.28/Mebel et al. (1998) /Clauberg et al. (1992)
c-C₃H₂	c- C₃H + H	284	136	5.00×10	0	B	C	Sect. 4.3.29/Mebel et al. (1998) /Clauberg et al. (1992)
l-C₄	C₃ + C	263	116	5.00×10	0	B	C	Sect. 4.3.30/Benedikt et al. (2005) /Ortiz (1993)
l-C₄H	C₄ + H	267	129	5.00×10	0	B	C	{ Sect. 4.3.31/van Hemert & van Dishoeck (2008)/ van Hemert & van Dishoeck (2008)
l-C₅H	C₅ + H	348	168	5.00×10	0	B	C	{ Sect. 4.3.32/van Hemert & van Dishoeck (2008)/ van Hemert & van Dishoeck (2008)
OH	O + H	279	95	4.07×10	0	A	B	{van Dishoeck & Dalgarno (1983); van Dishoeck & Dalgarno (1984a)/ Huber & Herzberg (1979) / Garcia et al. (2015)
OH⁺	O⁺ + H	247	–	2.58×10	0	A	A	Saxon & Liu (1986) /Levin et al. (2000) /–
H₂O	H + OH	242	98	1.53×10	0	A+	A+	Sect. 4.3.33/Mordaunt et al. (1994)/Page et al. (1988)
O₂	O + O	242	103	2.14×10	0	A	B	{ Sect. 4.3.35/Huber & Herzberg (1979)/ Dibeler & Walker (1967)
O	O + O⁺	186	–	2.52×10	0	B	C	Sect. 4.3.36/Huber & Herzberg (1979) /–
HO₂	H + O₂	476	109	5.00×10	0	C	C	{ McAdam et al. (1987), van Dishoeck (1988)/Sawyer (1989)/ Litorja & Ruscic (1998)
H₂O₂	OH + OH	556	117	9.65×10	0	A	A	Sect. 4.3.37/Holt et al. (1948) /Litorja & Ruscic (1998)
O₃	O₂ + O	1180	99	2.97×10	0	B	B	{ Sect. 4.3.38/Grebenshchikov et al. (2007)/ Willitsch et al. (2005)
CO	C + O	110	88	0	0	A+	–	{ Sect. 4.3.39/Tchang-Brillet et al. (1992)/ Zhao et al. (2014)
CO⁺	C⁺ + O	149	–	5.00×10	0	B	C	Sect. 4.3.40/Huber & Herzberg (1979) /–
CO₂	CO + O	227	90	6.54×10	0	A+	A+	Sect. 4.3.41/Song et al. (2014) /Wang et al. (1988)
HCO	H + CO	2037	152	5.00×10	0	C	C	{Bruna et al. (1976), van Dishoeck (1988)/ van Mourik et al. (2000) / Mayer & Grant (1995)
HCO⁺	H + CO⁺	145	–	0	0	B	–	Sect. 4.3.42/Koch et al. (1995b)/–
H₂CO	H₂ + CO	361	114	9.43×10	0	B	B	Sect. 4.3.43/Hopkins et al. (2007)/Guyon et al. (1976)
NH	N + H	362	92	3.10×10	0	B	B	Sect. 4.3.44/Gibson et al. (1985) /de Beer et al. (1991)
NH⁺	N⁺ + H	281	–	4.68×10	0	C	C	van Dishoeck & Black (1986)/Tarroni et al. (1997) /–
NH₂	NH + H	314	111	3.03×10	0	C	C	Sect. 4.3.45/Gibson et al. (1985) /Willitsch et al. (2006)
NH₃	NH + H₂	301	122	8.37×10	3.11×10	A+	A+	Sect. 4.3.46/Leach et al. (2005)/Herzberg (1966)
N₂	N + N	127	79	0	0	A+	–	Sect. 4.3.47/Roncin et al. (1989) /Klynning & Pages (1982)
NO	N + O	191	134	4.81×10	2.08×10	A	B	{ Sect. 4.3.48/Huber & Herzberg (1979)/ Huber & Herzberg (1979)
NO₂	NO + O	398	127	5.00×10	1.06×10	B	C	Lee (1984)/Lee & Chiang (1982) /Huber & Herzberg (1979)
N₂O	N₂ + O	735	96	3.85×10	0	B	C	Lee (1984)/Dibeler (1967) /Herzberg (1966)
CN	C + N	160	87	4.00×10	0	B	C	Sect. 4.3.49/Huang et al. (1992) /Berkowitz (1962)
HCN	H + CN	243	91	3.40×10	0	A	A	Sect. 4.3.50/Davis & Okabe (1968) /Fridh & Asbrink (1975)
HC₃N	H + C₃N	244	107	1.98×10	0	A	B	Sect. 4.3.51/Halpern et al. (1988) /Leach et al. (2014)
CH₃OH	CH₃O + H	280	113	1.39×10	0	A+	A+	Sect. 4.3.52/Nee et al. (1985) /Nee et al. (1985)
CH₃CN	CH₂CN + H	308	102	1.09×10	0	A	A	Sect. 4.3.53/Schwell et al. (2008) /Nuth & Glicker (1982)
CH₃SH	CH₃S + H	331	131	2.18×10	2.37×10	A	B	Sect. 4.3.60/Wilson et al. (1994)/Morgan et al. (1995)
CH₃CHO	HCO + CH₃	342	121	2.03×10	1.23×10	A	A	{ Sect. 4.3.54/Heazlewood et al. (2009)/ Knowles & Nicholson (1974)
CH₃NH₂	CH₃NH + H	244	135	0	2.44×10	A	A	Sect. 4.3.55/Hubin-Franskin et al. (2002) /Hu et al. (2002)
NH₂CHO	NH₃ + CO	208	121	1.82×10	1.88×10	A	A	Sect. 4.3.56/Gingell et al. (1997)/Leach et al. (2010)
C₂H₅OH	C₂H₅O + H	208	119	2.56×10	0	A	A	Sect. 4.3.57/Feng & Brion (2002)/Cool et al. (2005)
C₃H₇OH	C₃H₇O + H	208	123	5.16×10	2.80×10	A	A	{ Sect. 4.3.58/Salahub & Sandorfy (1971)/ Cool et al. (2005)
SH	S + H	345	119	8.07×10	0	B	C	{Sect. 4.3.67/ Peebles & Marshall (2002) / Hsu et al. (1994)
SH⁺	S⁺ + H	320	–	7.41×10	0	B	C	Sect. 4.3.64/Gustafsson et al. (1988)/–
H₂S	H + SH	318	119	5.39×10	0	A	A	Sect. 4.3.68/Shiell et al. (2000) /Cheng et al. (1998)
CS	C + S	169	110	5.36×10	0	C	C	{ Sect. 4.3.61/Coppens & Drowart (1995)/ Coppens & Drowart (1995)
CS₂	CS + S	278	123	1.71×10	1.04×10	A	A	Sect. 4.3.62/Okabe (1972)/Fischer et al. (1993)
OCS	CO + S	280	111	7.14×10	0	A	A	Sect. 4.3.59/Molina et al. (1981) /Wang et al. (1988)
S₂	S + S	283	133	0	1.80×10	B	C	Sect. 4.3.66/Frederix et al. (2009) /Liao & Ng (1986)
SO	S + O	233	120	1.06×10	0	B	C	{ Sect. 4.3.65/Reddy et al. (2000)/ Norwood & Ng (1989)
SO₂	O + SO	219	100	3.86×10	0	A	A	Sect. 4.3.63/Becker et al. (1995)/Holland et al. (1995)
SiH	Si + H	417	155	5.00×10	0	B	C	{ Lewerenz et al. (1983) /Neufeld & Wolfire (2009)/ Huber & Herzberg (1979)
SiH⁺	Si⁺ + H	391	–	2.22×10	0	A	B	van Dishoeck (1988)/Huber & Herzberg (1979) /–
SiO	Si + O	150	108	5.00×10	0	B	C	Sect. 4.3.69/Huber & Herzberg (1979) /Huber & Herzberg (1979)
HCl	H + Cl	279	97	9.19×10	0	A	A	Sect. 4.3.70/Huber & Herzberg (1979) /Weiss et al. (1970)
HCl⁺	H + Cl⁺	267	–	8.44×10	0	C	C	Sect. 4.3.71/Hotop et al. (1975) /–
NaCl	Na + Cl	293	–	5.00×10	0	C	C	{Silver et al. (1986), Zeiri & Balint-Kurti (1983)/ Huber & Herzberg (1979) / –
PH	P + H	398	122	1.13×10	0	C	C	{ Bruna et al. (1981) /Gao & Gao (2014)/ Berkowitz & Cho (1989)
PH⁺	P⁺ + H	369	–	1.06×10	0	C	C	Bruna et al. (1981) /Huber & Herzberg (1979) /–
AlH	Al + H	392	156	5.00×10	0	C	C	{ Sect. 4.3.72/Baltayan & Nedelec (1979)/ Marinelli & Allouche (1982)
LiH	Li + H	579	152	5.00×10	0	A	C	{ Kirby & Dalgarno (1978) /Neufeld & Wolfire (2009)/ Carmona-Novillo et al. (1996)
MgH	Mg + H	623	–	5.00×10	0	C	C	Kirby et al. (1979) /Neufeld & Wolfire (2009)/–
NaH	Na + H	606	179	5.00×10	0	A	C	{ Kirby & Dalgarno (1978) /Neufeld & Wolfire (2009)/ Langhoff (1985)

Notes.

^(a)

Photodissociation products at the threshold wavelength. We note that this is not necessarily the main product since significant (sometimes dominant) branching to other fragments is possible at shorter wavelengths. See discussion in Sects. 3.1, 3 for selected individual molecules and Sect. 8.6 for H₂O and NH₃.

^(b)

Long-wavelength threshold for the onset of dissociation or ionisation. For dissociation, the ground-state thermodynamic limit is given unless this is known to be inaccessible by photoexcitation, in that case a shorter wavelength limit is given.

^(c)

Photodissociation or ionisation cross section at the Lyman-α wavelength, 121.6 nm.

^(d)

Estimated uncertainty in the magnitude of the overall photodissociation cross section weighted by the ISRF, and at the Lyman-α wavelength in particular, rated according to the system: A+: accurate to within 20%. A: accurate to within 30%. B: accurate to within a factor of 2. C: accurate to within a factor of 10.

^(e)

Cross section source references or subsection where these are provided, and references for the given threshold wavelengths.

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