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Magnesium dimer


Gas phase thermochemistry data

Go To: Top, Gas phase ion energetics data, Constants of diatomic molecules, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Quantity Value Units Method Reference Comment
Deltafgas287.63kJ/molReviewChase, 1998Data last reviewed in September, 1983
Quantity Value Units Method Reference Comment
gas,1 bar240.19J/mol*KReviewChase, 1998Data last reviewed in September, 1983

Gas Phase Heat Capacity (Shomate Equation)

Cp° = A + B*t + C*t2 + D*t3 + E/t2
H° − H°298.15= A*t + B*t2/2 + C*t3/3 + D*t4/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 − E/(2*t2) + G
    Cp = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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View table.

Temperature (K) 298. - 800.800. - 2000.2000. - 4000.4000. - 6000.
A 21.4619014.49080682.8550-3665.920
B -2.45419110.38760-473.18301622.910
C 3.197761-6.352520119.7670-252.0680
D -1.4407311.367051-9.56987113.37470
E 0.2948351.196491-474.45306641.450
F 282.2990286.2340-613.72008255.660
G 268.4200259.8700481.2200833.0970
H 287.6250287.6250287.6250287.6250
ReferenceChase, 1998Chase, 1998Chase, 1998Chase, 1998
Comment Data last reviewed in September, 1983 Data last reviewed in September, 1983 Data last reviewed in September, 1983 Data last reviewed in September, 1983

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data evaluated by: Edward P. Hunter and Sharon G. Lias

Quantity Value Units Method Reference Comment
Proton affinity (review)919.kJ/molN/AHunter and Lias, 1998 
Quantity Value Units Method Reference Comment
Gas basicity886.5kJ/molN/AHunter and Lias, 1998 

Constants of diatomic molecules

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through March, 1977

Symbols used in the table of constants
SymbolMeaning
State electronic state and / or symmetry symbol
Te minimum electronic energy (cm-1)
ωe vibrational constant – first term (cm-1)
ωexe vibrational constant – second term (cm-1)
ωeye vibrational constant – third term (cm-1)
Be rotational constant in equilibrium position (cm-1)
αe rotational constant – first term (cm-1)
γe rotation-vibration interaction constant (cm-1)
De centrifugal distortion constant (cm-1)
βe rotational constant – first term, centrifugal force (cm-1)
re internuclear distance (Å)
Trans. observed transition(s) corresponding to electronic state
ν00 position of 0-0 band (units noted in table)
Diatomic constants for 24Mg2
StateTeomegaeomegaexeomegaeyeBealphaegammaeDebetaereTrans.nu00
C (1Sigmau+)     [0.1354] 1   [0.4E-6] 1  [3.222] 1 C larrow X V [38048.8] 1 Z
Balfour and Douglas, 1970
B (1Piu) 2           B larrow X 
Weniger, 1964; Edelhoff, Kusch, et al., 1968; Balfour and Douglas, 1970
A 1Sigmau+ 26068.76 190.615 Z 1.1456 3 0.001772 0.147999 0.0013164 0.1474E-5 0.334E-6 4  3.08186 A lrarrow X 5 6 V 26138.63 Z
Hamada, 1931; missing citation; missing citation
X 1Sigmag+ 0 51.121 Z 1.645 7 0.01624 0.09287 0.003776 8  1.217E-6 9  3.8905 10 11 

Notes

1Lowest observed level, vibrational numbering uncertain.
2Continuous absorption and diffusion bands, 35050 - 37600 cm-1, tentatively assigned to the 1Pi state arising from 1S + 1P.
3Vibrational numbering established by the observed 24Mg2 - 26Mg2 isotope shifts Balfour and Douglas, 1970.
4He = +0.23E-11.
5Franck-Condon factors and their dependence on rotation Balfour and Whitlock, 1972.
6Observed in Kr and Xe matrices by Brewer and Wang, 1971 and in Ne, Ar, N2 matrices by Knight and Ebener, 1976. The same authors also observe other absorptions probably related to B-X and C-X in the gas.
7omegaeze = -0.000611.
8missing note
9-0.031E-6(v+1/2) + 0.021E-6(v+1/2)2; Hv = -0.26E-10 - 0.085E- 10(v+1/2).
10Term values of ro-vibrational levels, RKR potential functions Balfour and Douglas, 1970, Li and Stwalley, 1973. For other potential functions see Brett and Chan, 1972, Muhlhausen and Konowalow, 1975.
11Long range potential studied by Stwalley, 1971, Li and Stwalley, 1973.
12From the convergence of the vibrational levels v=0...12 of the ground state Balfour and Douglas, 1970 including the slight extension (v=13) and correction by Li and Stwalley, 1973.
130.0001068(v+1/2)2 - 0.00000968(v+1/2)3.

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Balfour and Douglas, 1970
Balfour, W.J.; Douglas, A.E., Absorption spectrum of the Mg2 molecule, Can. J. Phys., 1970, 48, 901. [all data]

Weniger, 1964
Weniger, S., Spectre d'absorption de la vapeur de magnesium dans l'ultra-violet proche, J. Phys. (Paris), 1964, 25, 946. [all data]

Edelhoff, Kusch, et al., 1968
Edelhoff, B.; Kusch, H.J.; Lochte-Holtgreven, W., Untersuchung der absorption in der umgebung der MgI-resonanzlinie «lambda» = 2852 Å im kingschen ofen, Rev. Roum. Phys., 1968, 13, 2, 125-135. [all data]

Hamada, 1931
Hamada, H., III. On the molecular spectra of mercury, zinc, cadmium, magnesium, and thallium, Philos. Mag., 1931, 12, 50. [all data]

Balfour and Whitlock, 1972
Balfour, W.J.; Whitlock, R.F., Rotational dependence of Franck-Condon factors in the A1«SIGMA»u+ <-- X1«SIGMA»g+ system of 24Mg2, Can. J. Phys., 1972, 50, 1648. [all data]

Brewer and Wang, 1971
Brewer, L.; Wang, J.L.-F., Absorption spectrum of the Mg2 molecule in solid rare gases, J. Mol. Spectrosc., 1971, 40, 95. [all data]

Knight and Ebener, 1976
Knight, L.B.; Ebener, M.A., Matrix isolation of Mg2 and Mgn molecules in neon, argon, and nitrogen hosts, J. Mol. Spectrosc., 1976, 61, 412. [all data]

Li and Stwalley, 1973
Li, K.C.; Stwalley, W.C., Vibrational levels near dissociation in Mg2 and long-range forces, J. Chem. Phys., 1973, 59, 4423. [all data]

Brett and Chan, 1972
Brett, A.C.; Chan, C., The Mg2 potential: a curve fitting study, Can. J. Phys., 1972, 50, 1587. [all data]

Muhlhausen and Konowalow, 1975
Muhlhausen, C.W.; Konowalow, D.D., Hybrid potentials for the 1«SIGMA»g+ state of Mg2, Chem. Phys., 1975, 7, 143. [all data]

Stwalley, 1971
Stwalley, W.C., Polarizability and long-range interactions of magnesium atoms, J. Chem. Phys., 1971, 54, 4517. [all data]


Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, References