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Selenium dimer

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 July, 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 80Se2
F (1u) (55421) [430.2] H         (F larrow X2) V 54932.8 H
Barrow, Burton, et al., 1970
E 0u+ 54752.5 403.9 H 1.3  0.0924 0.00033    2.137 E larrow X2 1 V 54249
Barrow, Burton, et al., 1970; Greenwood and Barrow, 1976
           E larrow X1 V 54761.7 H
Barrow, Burton, et al., 1970
D (1u) (53075) [426.2] H   [0.0965]     [2.091] D larrow X1 2 V 53096.1 H
missing citation
C2 3Sigma-0+u (53324) [414] H 3        C2 larrow X1 V 53339 H
Barrow, Burton, et al., 1970
C1 3Sigma-1u 53220.5 428.0 H 1.22  0.09664 0.000333    2.0894 C1 larrow X2 V 52730.9 Z
missing citation
B2 3Sigma-1u 26058.6 246.42 4 Z 1.225  0.07086 5 6 0.000553  (2E-8)  2.4400 B2 lrarrow X2 7 8 R 25478.2 9
Barrow, Chandler, et al., 1966
           B2 rarrow X1 R 25989.2
Gouedard and Lehmann, 1976; Greenwood and Barrow, 1976
B1 3Sigma-0u+ 25980.36 246.291 4 10 Z 1.016 -0.00549 0.07048 11 0.000345  (4E-8)  2.4466 B1 rarrow X2 R 25399.8
Gouedard and Lehmann, 1976; Greenwood and Barrow, 1976
           B1 lrarrow X1 8 R 25910.84 Z
missing citation
X2 3Sigma-1g 510.0 12 387.156 13 Z 0.9640 13  0.09019 13 14 0.000299 13  (2E-8)  2.1628 15 
X1 3Sigma-0g+ 0 385.303 Z 0.96363 -0.0008814 0.08992 0.000288 -6.1E-7 2.4E-8 -0.023E-8 2.1660  


1This transition is much weaker than ElarrowX1.
2The assumption Barrow, Burton, et al., 1970 that this transition is C1larrowX1 has been withdrawn Greenwood and Barrow, 1976 since it gives the wrong X1-X2 splitting.
3Diffuse bands
4Vibrational analysis confirmed by isotope investigations Barrow, Chandler, et al., 1966.
5Average value, Be(F3) - Be(F2) = +0.00038.
6Rotational perturbations; a tentative analysis Yee and Barrow, 1972 of these and similar perturbations in the 0u+ component was based on an erroneous value of the 0u+ - 1u splitting. Predissociation in v=5 at J=72(F3) and 73(F2); bands with v'=6 have not been seen.
7Lifetime tau(v=0,J=105) = 58 ns, from Hanle effect measurements Dalby, Vigue, et al., 1975, Gouedard and Lehmann, 1975 combined with experimentally determined Lande gJ factors Gouedard and Lehmann, 1975, Gouedard and Lehmann, 1977.
8Various proposed other "systems" in the region 14500 -18500 cm-1 Rosen and Monfort, 1936, Leelavathi and Rao, 1955 have been shown Barrow, Chandler, et al., 1966 to belong to the main B-X system. Yee and Barrow, 1972 have extended the rotational analysis of the 78Se2 bands to higher values of v".
9Extrapo1ated from bands having v"geq8, using lower state constants of Barrow, Beattie, et al., 1971.
10The B1 0u+ state has a substantial potential maximum arising from an avoided crossing with a repulsive 0u+ state. The interaction strongly affects vibrational levels above v=15; the theoretical discussion by Atabek and Lefebvre, 1972 predicts irregular level shifts and widths above the crossing point.
11Sharp predissociation limits occur for v=4(J=106), v=5(J=82), v=6(J=50), leading to a dissociation limit at 27508 cm-1 above X1 0g+(v=0), and for v=13(J=96), v=14(J=78), v=15(J=50), leading to a dissociation limit at 29498 cm-1. Barrow, Chandler, et al., 1966 attribute the former to 3P2 + 3P1, the latter to 3P1 + 3P1. There are many rotational perturbations and several accidental predissociations; see also 6.
12From Greenwood and Barrow, 1976 whose measurements of fluorescence series in the range 6leq v"leq12 lead to Deltav = +509.95 + 2.1256(v+1/2) for the separation of the rotationless 1g and 0g+ substates.
13Constants apply to 8leqvleq29.
14Average of F2 and F3, Be(F3) - Be(F2) = +0.00006.
15For a theoretical calculation of the magnetic moment of Se2, consistent with experimental results, see Buchler and Meschi, 1975.
16From the predissociation in B1 0u+ (see 11) three possible spectroscopic values for the dissociation energy of 80Se2, i.e. D00 = 3.4105, 3.1638, 3.0964 eV, can be derived depending on the assumed atomic states at the observed predissociation limits. Barrow, Chandler, et al., 1966 prefer D00 = 3.164 eV on the basis of indirect spectroscopic arguments. However, both photoionization Berkowitz and Chupka, 1969, Radler and Berkowitz, 1977 and thermochemical studies [mass-spectrometry Berkowitz and Chupka, 1966, Colin and Drowart, 1968, Uy and Drowart, 1969, Knudsen-torsion effusion Budininkas, Edwards, et al., 1968; see also Meschi and Searcy, 1969, Smoes, Mandy, et al., 1972] strongly favor the higher value D00 = 3.411 eV.
17Photoionization mass-spectrometry Berkowitz and Chupka, 1969. From the photoelectron spectrum Streets and Berkowitz, 1976 derive adiabatic and vertical ionization potentials of 8.70 and 8.89 eV, respectively.


Go To: Top, 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.

Barrow, Burton, et al., 1970
Barrow, R.F.; Burton, W.G.; Callomon, J.H., Absorption spectrum of gaseous 80Se2 in the region 51500-55000 cm-1, J. Chem. Soc. Faraday Trans., 1970, 66, 2685. [all data]

Greenwood and Barrow, 1976
Greenwood, D.J.; Barrow, R.F., A medium-resolution study of fluorescence in 80Se2 excited by lines of the argon-ion laser, J. Phys. B:, 1976, 9, 2123. [all data]

Barrow, Chandler, et al., 1966
Barrow, R.F.; Chandler, G.G.; Meyer, C.B., The B(3«SIGMA»u-) - X(3«SIGMA»g-) band system of the Se2 molecule, Philos. Trans. R. Soc. London A, 1966, 260, 395. [all data]

Gouedard and Lehmann, 1976
Gouedard, G.; Lehmann, J.C., Fine-structure determinations in the X3«SIGMA»g- and B3«SIGMA»u- states of 80Se2, J. Phys. B:, 1976, 9, 2113. [all data]

Yee and Barrow, 1972
Yee, K.K.; Barrow, R.F., Absorption and fluorescence spectra of gaseous Se2, J. Chem. Soc. Faraday Trans. 2, 1972, 68, 1181. [all data]

Dalby, Vigue, et al., 1975
Dalby, F.W.; Vigue, J.; Lehmann, J.C., On Hanle effects in the B(3«SIGMA»u-)-X(3«SIGMA»g-) band system of the Se2 molecule, Can. J. Phys., 1975, 53, 140. [all data]

Gouedard and Lehmann, 1975
Gouedard, G.; Lehmann, J.-C., Effet hanle et resonances en lumiere modulee sur le niveau B1u,v'=O, J'=105 de la molecule (80Se)2 excitee par la raie 4 727 Å d'un laser a argon ionise, C.R. Acad. Sci. Paris, Ser. B, 1975, 280, 471. [all data]

Gouedard and Lehmann, 1977
Gouedard, G.; Lehmann, J.C., Lande factors measurements in the B3«SIGMA»u- state of 80Se2, J. Phys. Lett., 1977, 38, 85. [all data]

Rosen and Monfort, 1936
Rosen, B.; Monfort, F., Etude du spectre du selenium dans le rouge et l'infrarouge photographique, Physica (The Hague), 1936, 3, 257. [all data]

Leelavathi and Rao, 1955
Leelavathi, V.; Rao, P.T., The visible emission spectrum of Se2, Indian J. Phys., 1955, 29, 1. [all data]

Barrow, Beattie, et al., 1971
Barrow, R.F.; Beattie, I.R.; Burton, W.G.; Gilson, T., Resonance fluorescence spectra of 80Se2, Trans. Faraday Soc., 1971, 67, 583. [all data]

Atabek and Lefebvre, 1972
Atabek, O.; Lefebvre, R., Evaluation of the level shifts produced on the discrete levels of the BOu+ state of the Se2 molecule by the interaction with a repulsive state, Chem. Phys. Lett., 1972, 17, 167. [all data]

Buchler and Meschi, 1975
Buchler, A.; Meschi, D.J., The magnetic moment of Se2, J. Chem. Phys., 1975, 63, 3586. [all data]

Berkowitz and Chupka, 1969
Berkowitz, J.; Chupka, W.A., Photoionization of high-temperature vapors. VI. S2, Se2, and Te2, J. Chem. Phys., 1969, 50, 4245. [all data]

Radler and Berkowitz, 1977
Radler, K.; Berkowitz, J., Photoionization mass spectrometric study of CSe2, J. Chem. Phys., 1977, 66, 2176. [all data]

Berkowitz and Chupka, 1966
Berkowitz, J.; Chupka, W.A., Equilibrium composition of selenium vapor; the thermodynamics of the vaporization of HgSe, CdSe, and SrSe, J. Chem. Phys., 1966, 45, 4289. [all data]

Colin and Drowart, 1968
Colin, R.; Drowart, J., Mass spectrometric determination of dissociation energies of gaseous indium sulphides, selenides and tellurides, J. Chem. Soc. Faraday Trans., 1968, 64, 2611. [all data]

Uy and Drowart, 1969
Uy, O.M.; Drowart, J., Mass spectrometric determination of the dissociation energies of the molecules BiO, BiS, BiSe and BiTe, J. Chem. Soc. Faraday Trans., 1969, 65, 3221. [all data]

Budininkas, Edwards, et al., 1968
Budininkas, P.; Edwards, R.K.; Wahlbeck, P.G., Dissociation energies of group VIa gaseous homonuclear diatomic molecules. II. Selenium, J. Chem. Phys., 1968, 48, 2867. [all data]

Meschi and Searcy, 1969
Meschi, D.J.; Searcy, A.W., Investigation of the magnetic moments of S2, Se2, Te2, Se6, and Se5 by the Stern-Gerlach magnetic deflection method, J. Chem. Phys., 1969, 51, 5134. [all data]

Smoes, Mandy, et al., 1972
Smoes, S.; Mandy, F.; Vander Auwera-Mahieu, A.; Drowart, J., Determination by the mass spectrometric Knudsen cell method of the dissociation energies of the group IB chalcogenides, Bull. Soc. Chim. Belg., 1972, 81, 45. [all data]

Streets and Berkowitz, 1976
Streets, D.G.; Berkowitz, J., Photoelectron spectroscopy of Se2 and Te2, J. Electron Spectrosc. Relat. Phenom., 1976, 9, 269. [all data]


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