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Constants of diatomic molecules

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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
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 23Na127I+
A (2Sigma) 9520 1 2           
X (2Pi1/2) 1770 1 2           
X (2Pi3/2) 0 1 2           


1From the maxima in the photoelectron spectrum Goodman, Allen, et al., 1974, Potts, Williams, et al., 1974.
2Removal of an electron from the halogen 5p shell of Na+ I-.
3Dissociative photoionization of NaI Berkowitz and Chupka, 1966. Thermochemical values Brewer and Brackett, 1961 tend to be slightly higher, atomic fluorescence gives slightly lower values (neglecting, however, the thermal population of the ground state vibrational levels); for references see Berkowitz and Chupka, 1966. Flame photometry suggests 3.13 eV Bulewicz, Phillips, et al., 1961.
4From photoionization Berkowitz and Chupka, 1966; in good agreement with the photoelectron spectrum Potts, Williams, et al., 1974.
5In inert gas matrices absorption bands from 25000 to 26000 cm-1 Oppenheimer and Berry, 1971; the vibrational interval in Ar is ~ 166.
6UV absorption cross sections Davidovits and Brodhead, 1967.
7From the IR spectrum Rice and Klemperer, 1957. Application of the Dunham relations to the microwave results of Rusk and Gordy, 1962 gives we = 259.20, wexe = 0.964.
8muel[D] = 9.2103 + 0.0507(v+1/2), v leq2 Hebert, Lovas, et al., 1968. Electric quadrupole coupling constants, dependence on v Miller and Zorn, 1969; earlier results by the magnetic resonance method Nierenberg and Ramsey, 1947, Logan, Cote, et al., 1952, Cote and Kusch, 1953.
9gJ = (+)0.027 muN Mehran, Brooks, et al., 1966.
10From D00(NaI) + I.P.(Na) - I.P.(NaI); Potts, Williams, et al., 1974 give 0.60 eV.


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

Goodman, Allen, et al., 1974
Goodman, T.D.; Allen, J.D., Jr.; Cusachs, L.C.; Schweitzer, G.K., The photoelectron spectra of gaseous alkali halides, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 289. [all data]

Potts, Williams, et al., 1974
Potts, A.W.; Williams, T.A.; Price, W.C., Photoelectron spectra and electronic structure of diatomic alkali halides, Proc. Roy. Soc. London A, 1974, 341, 147. [all data]

Berkowitz and Chupka, 1966
Berkowitz, J.; Chupka, W.A., Photoionization of high-temperature vapors. I. The iodides of sodium, magnesium, and thallium, J. Chem. Phys., 1966, 45, 1287. [all data]

Brewer and Brackett, 1961
Brewer, L.; Brackett, E., The dissociation energies of gaseous alkali halides, Chem. Rev., 1961, 61, 425. [all data]

Bulewicz, Phillips, et al., 1961
Bulewicz, E.M.; Phillips, L.F.; Sugden, T.M., Determination of dissociation constants and heats of formation of simple molecules by flame photometry. Part 8. Stabilities of the gaseous diatomic halides of certain metals, Trans. Faraday Soc., 1961, 57, 921. [all data]

Oppenheimer and Berry, 1971
Oppenheimer, M.; Berry, R.S., Ultraviolet spectra of alkali halides in inert matrices, J. Chem. Phys., 1971, 54, 5058. [all data]

Davidovits and Brodhead, 1967
Davidovits, P.; Brodhead, D.C., Ultraviolet absorption cross sections for the alkali halide vapors, J. Chem. Phys., 1967, 46, 2968. [all data]

Rice and Klemperer, 1957
Rice, S.A.; Klemperer, W., Spectra of the alkali halides. II. The infrared spectra of the sodium and potassium halides, RbCl, and CsCl, J. Chem. Phys., 1957, 27, 573. [all data]

Rusk and Gordy, 1962
Rusk, J.R.; Gordy, W., Millimeter wave molecular beam spectroscopy: alkali bromides and iodides, Phys. Rev., 1962, 127, 817. [all data]

Hebert, Lovas, et al., 1968
Hebert, A.J.; Lovas, F.J.; Melendres, C.A.; Hollowell, C.D.; Story, T.L., Jr.; Street, K., Jr., Dipole moments of some alkali halide molecules by the molecular beam electric resonance method, J. Chem. Phys., 1968, 48, 2824. [all data]

Miller and Zorn, 1969
Miller, C.E.; Zorn, J.C., Hyperfine structure of sodium iodide, J. Chem. Phys., 1969, 50, 3748. [all data]

Nierenberg and Ramsey, 1947
Nierenberg, W.A.; Ramsey, N.F., The radiofrequency spectra of the sodium halides, Phys. Rev., 1947, 72, 1075. [all data]

Logan, Cote, et al., 1952
Logan, R.A.; Cote, R.E.; Kusch, P., The sign of the quadrupole interaction energy in diatomic molecules, Phys. Rev., 1952, 86, 280. [all data]

Cote and Kusch, 1953
Cote, R.E.; Kusch, P., Low frequency resonances in the spectra of diatomic molecules, Phys. Rev., 1953, 90, 103. [all data]

Mehran, Brooks, et al., 1966
Mehran, F.; Brooks, R.A.; Ramsey, N.F., Rotational magnetic moments of alkali-halide molecules, Phys. Rev., 1966, 141, 93. [all data]


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