Selected ATcT [1, 2] enthalpy of formation based on version 1.202 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.176 in order to include species related to the thermochemistry of glycine[4].

Helium dication

Formula: [He]+2 (g)

CAS RN: 12587-46-1

ATcT ID: 12587-46-1*0

SMILES: [He++]

InChI: InChI=1S/He/q+2

InChIKey: LBDSXVIYZYSRII-UHFFFAOYSA-N

Hills Formula: He1+2

2D Image:

Aliases: [He]+2; Helium dication; Helium atom dication; Atomic helium dication; Alpha particle; Alpha ray; 14127-62-9; He++

Relative Molecular Mass: 4.0015048 ± 0.0000020

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
7622.839	7622.839	± 0.000	kJ/mol

3D Image of [He]+2 (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of [He]+2 (g)

The 4 contributors listed below account for 90.8% of the provenance of Δ_fH° of [He]+2 (g).

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
45.5	9483.1	He (g) → He+ (g)	Δ_rH°(0 K) = 198310.66637 ± 0.00040 cm-1	Kandula 2010, note unc, Tiesinga 2021
19.7	9484.7	He+ (g) → [He]+2 (g)	Δ_rH°(0 K) = 438908.8785 ± 0.0004 cm-1	Johnson 1985, note std dev, Tiesinga 2021
19.7	9484.5	He+ (g) → [He]+2 (g)	Δ_rH°(0 K) = 438908.8782 ± 0.0002 cm-1	Erickson 1977, note std dev
5.8	9483.10	He (g) → He+ (g)	Δ_rH°(0 K) = 198310.6667 ± 0.0028 cm-1	Korobov 2001, note unc

Top 10 species with enthalpies of formation correlated to the Δ_fH° of [He]+2 (g)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation Coefficent (%)	Species Name	Formula	Image	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
77.6	Helium cation	He+ (g)		2372.322	2372.322	± 0.000	kJ/mol	4.0020534 ± 0.0000020	14234-48-1*0

Most Influential reactions involving [He]+2 (g)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
0.497	9484.7	He+ (g) → [He]+2 (g)	Δ_rH°(0 K) = 438908.8785 ± 0.0004 cm-1	Johnson 1985, note std dev, Tiesinga 2021
0.497	9484.5	He+ (g) → [He]+2 (g)	Δ_rH°(0 K) = 438908.8782 ± 0.0002 cm-1	Erickson 1977, note std dev
0.005	9484.3	He+ (g) → [He]+2 (g)	Δ_rH°(0 K) = 438908.877 ± 0.010 cm-1	Garcia 1965

References

1		B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner, Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited. J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2		B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner, Active Thermochemical Tables: Thermochemistry for the 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.202 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		B. Ruscic and D. H. Bross Accurate and Reliable Thermochemistry by Data Analysis of Complex Thermochemical Networks using Active Thermochemical Tables: The Case of Glycine Thermochemistry Faraday Discuss. (in press) (2024) [DOI: 10.1039/D4FD00110A]
5		B. Ruscic, Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
6		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [5] and Ruscic and Bross[6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.