Dilead

Gas phase thermochemistry data

Go To: Top, 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
ΔfH°gas79.500kcal/molReviewChase, 1998Data last reviewed in September, 1963
Quantity Value Units Method Reference Comment
S°gas,1 bar67.239cal/mol*KReviewChase, 1998Data last reviewed in September, 1963

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 (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Temperature (K) 298. to 6000.
A 8.934730
B 0.394538
C -0.001759
D 0.000150
E -0.020381
F 76.75041
G 77.82051
H 79.50010
ReferenceChase, 1998
Comment Data last reviewed in September, 1963

Constants of diatomic molecules

Go To: Top, Gas phase thermochemistry 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 May, 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 (208)Pb2
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
Emission bands in the region 12500 - 11100 cm-1, observed in Ar and Ne matrices by excitation with argon/krypton ion laser lines.
↳Teichman and Nixon, 1976
Absorption bands in the region 33400 - 34600 cm-1 (preceded by continuous fluctuations from 31300 to 33300 cm-1), 36800 - 38000, and 41000 - 42200 cm-1.
↳Weniger, 1967
B 19490.3 161.64 1 H 1.036 0.0055       B ↔ X 2 R 19515.7 H
↳missing citation; missing citation; Johnson, Cannell, et al., 1972
A 14465.6 162.4 1 0.4        A ↔ X 3 (R) 14491.5
↳missing citation; Johnson, Cannell, et al., 1972; Puri and Mohan, 1975
StateTeωeωexeωeyeBeαeγeDeβereTrans.ν00
X 0 110.5 1 4 H 0.35         

Notes

1Constants obtained by Johnson, Cannell, et al., 1972 from a reclassification of bands in the blue-green and in the red system. The new analysis of the ground state seems to be confirmed by the observation of a lower state frequency of 111 cm-1 in laser-excited matrix emission spectra [see Teichman and Nixon, 1976 who attribute the 111 cm-1 interval to a matrix-induced splitting of the ground state]. The revised lower state constants imply, however, a strong contradiction to the usual rule that if ω' > ω" then B' > B" since according to the published spectrograms of Weniger, 1967 the B-X bands are strongly shaded to the red, i.e. B' < B".
2Previously called A-X. Also observed in inert gas matrices Brewer and Chang, 1972, Teichman and Nixon, 1976.
3Previously believed to have B as its lower state.
4 Johnson, Cannell, et al., 1972 give 119.1 which seems to be a typographical or arithmetical error since it does not represent the band head measurements of Shawhan, 1935.
5Thermochemical value (mass-spectrom.) Gingerich, Cocke, et al., 1976.

References

Go To: Top, Gas phase thermochemistry 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]

Teichman and Nixon, 1976
Teichman, R.A., III; Nixon, E.R., Absorption and laser-excited emission spectra of matrix-isolated Pb2, J. Mol. Spectrosc., 1976, 59, 299. [all data]

Weniger, 1967
Weniger, S., Etude du spectre d'absorption de la molecule de plomb, J. Phys. (Paris), 1967, 28, 595. [all data]

Johnson, Cannell, et al., 1972
Johnson, S.E.; Cannell, D.; Lunacek, J.; Broida, H.P., New molecular constants for the ground electronic state of Pb2, J. Chem. Phys., 1972, 56, 5723. [all data]

Puri and Mohan, 1975
Puri, S.N.; Mohan, H., Thermal emission spectrum (intercombinational system) of Pb2, Indian J. Pure Appl. Phys., 1975, 13, 206-207. [all data]

Brewer and Chang, 1972
Brewer, L.; Chang, C.-A., Matrix isolation of Pb and Pb2, J. Chem. Phys., 1972, 56, 1728. [all data]

Shawhan, 1935
Shawhan, E.N., Band spectrum of Pb2 in absorption and emission, Phys. Rev., 1935, 48, 343. [all data]

Gingerich, Cocke, et al., 1976
Gingerich, K.A.; Cocke, D.L.; Miller, F., Thermodynamic investigation of the lead molecules Pb2, Pb3, and Pb4 by mass spectrometry, J. Chem. Phys., 1976, 64, 4027. [all data]

Notes

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