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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 July, 1976

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 19F2
Many strong absorption bands observed and partially analyzed up to 126000 cm-1, heavily perturbed and not assigned. 1
missing citation
K 1Πu     [1.040] 2 3    [1.306] K ← X V 11655.72 Z
Gole and Margrave, 1972; missing citation
J 1Πu (4p σ) 116409 [1032.6] Z   [1.041] 3    [1.306] J ← X V 116469.4 Z
missing citation
I 1Σu+ (4p π) 113841 [1108.92] Z 4  [0.8009] 5  [1.8E-6] 6  1.4886 I → f R 17081.6 $I H
missing citation; Stricker and Krauss, 1968; Colbourn, Dagenais, et al., 1976
           I → F R 20732 7 H
missing citation; Stricker and Krauss, 1968; Colbourn, Dagenais, et al., 1976
           I ↔ X 8 R 113940.24 Z
di Lonardo and Douglas, 1972; Gole and Margrave, 1972; missing citation
H 1Πu (3pσ) 105520.14 1088.19 Z 9.875  1.021 9 0.014    1.318 H ← X V 105606.27 Z
Gole and Margrave, 1972; Colbourn, Dagenais, et al., 1976
h 3Π1u (3pσ) (104904) (1100) 10   1.022 11 0.016    1.318 h ← X V 104998.7 Z
Colbourn, Dagenais, et al., 1976
G 1Σu+ (3pπ) (104300) 12           
Colbourn, Dagenais, et al., 1976
E (1Σu+) ≤100912 [196.3] 13 Z (0.96)  [0.194] 13     [3.02] 13 E ← X R 100555.5 13 Z
missing citation
D (1Σu+) ≤98756 [221.6] 13 Z (1.22)  [0.207] 13     [2.93] 13 D ← X R 98411.9 13 Z
missing citation
f (3Π1g) (3sσ) [97314] 14 14   [1.005] 14     [1.329] 14  
C 1Σu+ ≤93499 [493.2] 15 Z   [0.484] 15     [1.915] 15 C ↔ X R 93290.4 15 Z
missing citation
F 1Πg (3sσ) 93099 1133.34 16 H 9.173  1.047 16 0.012    1.302  
A 1Πu 17           A ← X 
Steunenberg and Vogel, 1956; Rees, 1957
a 3Π0+u 19           a ← X 18 
Steunenberg and Vogel, 1956; Rees, 1957
X 1Σg+ 0 916.64 Z 11.236 20 -0.113 0.89019 0.013847 21  3.3E-6  1.41193 22  
Andrychuk, 1951; Claassen, Selig, et al., 1969; Stricker and Hochenbleicher, 1973; Edwards, Good, et al., 1976
Mol. beam magn. reson. 23
Ozier, Crapo, et al., 1964
Ab initio calc.
Das and Wahl, 1972


1The assignments to two Rydberg series by Gole and Margrave, 1972 are questioned by Colbourn, Dagenais, et al., 1976.
2BQ; BPR = 1.034.
3B2 = 0.9916.
4ΔG(3/2)=754.06, ΔG(5/2)=553.78, ΔG(7/2)=733.01; strongly perturbed, not certain whether one or two electronic states are involved.
5B1= 0.8129, B2= 0.8980, B3= 0.8946, B4= 0.891; see 4.
6Dv(v=1...4, E-6 cm-1) = 4.0, 14.0, -2.6, -50.0
7v" uncertain, see 16.
8Four of the strongest absorption bands; in emission only bands with v=0 and 1 and very weakly v=2.
9From Q branches, BQ - BPR ~ +0.004. v' = 0,1,2,3 analyzed, a weak and highly perturbed band at 911 (109770 cm-1) may be 4-0.
10Estimated from the 0-0 and 2-0 (v0= 107069.4) bands.
11From Q branches; BQ - BPR = +0.005. v=0 strongly perturbed.
12Infrared from strong perturbation of the higher vibrational levels of C 1Σu+.
13(Deperturbed) constants determined from the lowest observed levels; vibrational numbering unknown. Only those levels which interact strongly with C 1Σu+ have been found in absorption. It is possible that D and E are not two independent states.
14From I →f Porter, 1968; vibrational numbering unknown. The assignments of Stricker and Krauss, 1968 suggest the existence of additional levels at 1058 below and 1044 cm-1 above the single level reported by Porter, 1968.
15Constants for the lowest observed level, vibrational numbering unknown (v=n). In absorption levels up to v = n+30 have been observed. Numerous perturbations by levels of D and E (interaction matrix elements ~ 10 cm-1); a much stronger interaction with G affects levels having v «gte» n+25. For details see Table 5 of Colbourn, Dagenais, et al., 1976.
16Vibrational numbering uncertain. Extensive perturbations. Strong predissociation leading to line broadening in I→F bands having v" = 1,2,4,5,6,8; bands with v"= 3,7 are sharp.
17Continuous absorption with maximum at 35000 cm-1.
18The existence of the a ←X absorption becomes clear only after subtraction of the much stronger effect of the A←X absorption from the observed absorption intensities Rees, 1957. It is generally assumed that the 3Π0+u state has a minimum but no discrete absorption or emission has been observed, see Nathans, 1950. Child and Bernstein, 1973 predict a dissociation energy De= 3300 cm-1 and re= 1.9 for this state.
19Continuous absorption with maximum at 25500 cm-1.
20These constants represent only the lowest nine levels (i.e. v≤8) Colbourn, Dagenais, et al., 1976. Levels have been observed up to v=22; this last level lies only 90 cm-1 below the extrapolated limit.
21+0.0001179(v+1/2)2 - 0.0000203(v+1/2)3, representing B0....B12.
22Raman sp.
23Rotational gyromagnetic ratio gJ = -0.1208 μN (nuclear) spin-rotation and spin- spin interaction constants c = -157.3 kHz, d = 8.0 kHz.
24From the observed vibrational levels of the ground state Colbourn, Dagenais, et al., 1976; the highest observed level (presumably the last stable level) is at 12830.38 cm-1. Shock tube experiments of Blauer and Solomon, 1972 give the same value within ±0.05 eV; see also the earlier work of Barrow and Caunt, 1953, Stamper and Barrow, 1958, DeCorpo, Steiger, et al., 1970.
25From photoionization Berkowitz, Chupka, et al., 1971. Photoelectron spectra Cornford, Frost, et al., 1971 give 15.70 eV.
26The lower state vibrational numbering of this band is unknown, see 14.


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

Gole and Margrave, 1972
Gole, J.L.; Margrave, J.L., The vacuum ultraviolet spectrum of molecular fluorine, J. Mol. Spectrosc., 1972, 43, 65. [all data]

Stricker and Krauss, 1968
Stricker, W.; Krauss, L., Die Bestimmung der Dissoziationsenergie des F2-Molekuls und ein Beitrag zu seinem Bandenspektrum, Z. Naturforsch. A, 1968, 23, 486. [all data]

Colbourn, Dagenais, et al., 1976
Colbourn, E.A.; Dagenais, M.; Douglas, A.E.; Raymonda, J.W., The electronic spectrum of F2, Can. J. Phys., 1976, 54, 1343. [all data]

di Lonardo and Douglas, 1972
di Lonardo, G.; Douglas, A.E., Electronic spectra of HF and F2, J. Chem. Phys., 1972, 56, 5185. [all data]

Steunenberg and Vogel, 1956
Steunenberg, R.K.; Vogel, R.C., The absorption spectrum of fluorine, J. Am. Chem. Soc., 1956, 78, 901. [all data]

Rees, 1957
Rees, A.L.G., Erratum: Electronic spectrum and dissociation energy of fluorine, J. Chem. Phys., 1957, 27, 1424. [all data]

Andrychuk, 1951
Andrychuk, D., The Raman spectrum of fluorine, Can. J. Phys., 1951, 29, 151. [all data]

Claassen, Selig, et al., 1969
Claassen, H.H.; Selig, H.; Shamir, J., Raman apparatus using laser excitation and polarization measurements. Rotational spectrum of fluorine, Appl. Spectrosc., 1969, 23, 8. [all data]

Stricker and Hochenbleicher, 1973
Stricker, W.; Hochenbleicher, J.G., Das lasererregte Raman-Spektrum von gasformigem Fluor, Z. Naturforsch. A, 1973, 28, 27. [all data]

Edwards, Good, et al., 1976
Edwards, H.G.M.; Good, E.A.M.; Long, D.A., Pure rotational Raman spectrum of fluorine, J. Chem. Soc. Faraday Trans. 2, 1976, 72, 984-987. [all data]

Ozier, Crapo, et al., 1964
Ozier, I.; Crapo, L.M.; Cederberg, J.W.; Ramsey, N.F., Nuclear interactions and rotational moment of F2, Phys. Rev. Lett., 1964, 13, 482. [all data]

Das and Wahl, 1972
Das, G.; Wahl, A.C., Theoretical study of the F2 molecule using the method of optimized valence configurations, J. Chem. Phys., 1972, 56, 3532. [all data]

Porter, 1968
Porter, T.L., Emission spectrum of molecular fluorine, J. Chem. Phys., 1968, 48, 2071. [all data]

Nathans, 1950
Nathans, M.W., The absorption spectrum and the dissociation energy of fluorine, J. Chem. Phys., 1950, 18, 1122. [all data]

Child and Bernstein, 1973
Child, M.S.; Bernstein, R.B., Diatomic interhalogens: systematics and implications of spectroscopic interatomic potentials and curve crossings, J. Chem. Phys., 1973, 59, 5916. [all data]

Blauer and Solomon, 1972
Blauer, J.; Solomon, W., Shock tube calorimeter for the dissociation energy of fluorine, J. Chem. Phys., 1972, 57, 3587. [all data]

Barrow and Caunt, 1953
Barrow, R.F.; Caunt, A.D., The ultra-violet absorption spectra of some gaseous alkali-metal halides and the dissociation energy of fluorine, Proc. R. Soc. London A, 1953, 219, 120. [all data]

Stamper and Barrow, 1958
Stamper, J.G.; Barrow, R.F., The dissociation energy of fluorine, Trans. Faraday Soc., 1958, 54, 1592. [all data]

DeCorpo, Steiger, et al., 1970
DeCorpo, J.J.; Steiger, R.P.; Franklin, J.L.; Margrave, J.L., Dissociation energy of F2, J. Chem. Phys., 1970, 53, 936. [all data]

Berkowitz, Chupka, et al., 1971
Berkowitz, J.; Chupka, W.A.; Guyon, P.M.; Holloway, J.H.; Spohr, R., Photoionization mass spectrometric study of F2, HF, and DF, J. Chem. Phys., 1971, 54, 5165. [all data]

Cornford, Frost, et al., 1971
Cornford, A.B.; Frost, D.C.; McDowell, C.A.; Ragle, J.L.; Stenhouse, I.A., Photoelectron spectra of the halogens, J. Chem. Phys., 1971, 54, 2651. [all data]


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