Cesium dimer
- Formula: Cs2
- Molecular weight: 265.8109038
- IUPAC Standard InChI: InChI=1S/2Cs
- IUPAC Standard InChIKey: KNJJHXOVFHKJEY-UHFFFAOYSA-N
- CAS Registry Number: 12184-83-7
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Gas phase thermochemistry data
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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°gas | 25.662 | kcal/mol | Review | Chase, 1998 | Data last reviewed in December, 1983 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 68.033 | cal/mol*K | Review | Chase, 1998 | Data last reviewed in December, 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 (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 298. to 1500. | 1500. to 6000. |
|---|---|---|
| A | 6.978710 | 10.09570 |
| B | 10.14290 | -4.443339 |
| C | -13.38790 | 1.294240 |
| D | 4.311860 | -0.102151 |
| E | 0.018461 | 1.373810 |
| F | 23.29970 | 25.00939 |
| G | 74.11561 | 83.48229 |
| H | 25.66109 | 25.66109 |
| Reference | Chase, 1998 | Chase, 1998 |
| Comment | Data last reviewed in December, 1983 | Data last reviewed in December, 1983 |
Gas phase ion energetics data
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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 as indicated in comments:
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
B - John E. Bartmess
View reactions leading to Cs2+ (ion structure unspecified)
Electron affinity determinations
| EA (eV) | Method | Reference | Comment |
|---|---|---|---|
| 0.469 ± 0.015 | LPES | McHugh, Eaton, et al., 1989 | Vertical Detachment Energy: 0.511±0.010 eV; B |
Ionization energy determinations
| IE (eV) | Method | Reference | Comment |
|---|---|---|---|
| 3.7 ± 0.1 | PI | Kappes, Radi, et al., 1985 | LBLHLM |
| ≤3.76 ± 0.06 | S | Helm and Moller, 1983 | LBLHLM |
| 3.68 | EVAL | Marr and Wherrett, 1972 | LLK |
| 3.60 | PI | Marr and Wherrett, 1972 | LLK |
| 3.8 ± 0.1 | PI | Foster, Leckenby, et al., 1969 | RDSH |
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 October, 1976
| Symbol | Meaning |
|---|---|
| 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) |
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Unidentified structure in the absorption spectrum from 31800 to 34900, 36700 to 41700 cm-1. | ||||||||||||
| ↳Creek and Marr, 1968 | ||||||||||||
| Fragments of other systems, as well as diffuse bands near atomic lines. 1 | ||||||||||||
| ↳Loomis and Kusch, 1934; Ny-Tsi-Ze and Shang-Yi, 1938 | ||||||||||||
| (E) 3 | E ↔ X 2 | |||||||||||
| ↳missing citation; Lapp and Harris, 1966; Baumgartner, Demtroder, et al., 1970 | ||||||||||||
| D 4 | D ← X | |||||||||||
| ↳Loomis and Kusch, 1934; Lapp and Harris, 1966 | ||||||||||||
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
| C (1Πu) 1u | 15948.60 | 29.703 5 (Z) | 0.0576 5 | 0.01347 6 | 0.0000785 | 1.210E-08 7 | -1.93E-10 | 4.340 | C ↔ X 2 VR | 15942.45 (Z) | ||
| ↳missing citation; Kusch and Loomis, 1936; Kusch and Hessel, 1968 | ||||||||||||
| B (1Πu) 1u | 13043.88 | 34.329 8 H | 0.0800 8 | B ← X R | 13040.03 H | |||||||
| ↳missing citation; Kusch and Hessel, 1969 | ||||||||||||
| A (1Σ+u) 9 | A ↔ X R | |||||||||||
| ↳Loomis and Kusch, 1934; Finkelnburg and Hahn, 1938; Bayley, Eberlin, et al., 1968; Sorokin and Lankard, 1971 | ||||||||||||
| b (3Πu) 10 | b ↔ X | |||||||||||
| ↳Bayley, Eberlin, et al., 1968; Sorokin and Lankard, 1971 | ||||||||||||
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
| a 3Σu+ | (3140) 11 | |||||||||||
| X 2Σg+ | 0 | 42.022 12 | 0.0823 12 | 0.01271 6 | 0.0000264 | 4.64E-09 6 | 4.47 13 | |||||
Notes
| 1 | Satellites and self-broadening of Cs principal lines Niemax, 1972 Niemax and Pichler, 1974. Resonances in the two-photon ionization spectrum of cesium corresponding to the fundamental and diffuse series in absorption result from reactions initiated by molecular transitions to intermediate dissociative states; see Collins, Johnson, et al., 1974. |
| 2 | Intermediates in the two-photon ionization of Cs2 Collins, Johnson, et al., 1973, Granneman, Klewer, et al., 1976. |
| 3 | Strong system in the region 19140 - 21700, maximum at 20800 cm-1. |
| 4 | Weak system in the region 16500 - 18000 cm-1. |
| 5 | ωe,...,ωeze obtained Kusch and Hessel, 1968 from V shaded P heads [also observed in the magnetic rotation spectrum Kusch and Hessel, 1969] and calculated head-origin separations; see 6. |
| 6 | The rotational structure of the C-X bands is not resolved. The rotational constants for both states are based on estimated values for B0", D0" and have been adjusted to reproduce the observed V as well as R shaded heads in the P, Q, and R branches. The red-degraded heads occur through the D terms in the rotational energy expressions. See Kusch and Hessel, 1968. |
| 7 | See 6. |
| 8 | ωe,...,ωeze from band heads in the magnetic rotation spectrum Kusch and Hessel, 1969. Vibrational levels up to v'= 83 observed in absorption. The B state extrapolates to a potential maximum at ~ 250 cm-1 above 6 2P3/2 + 6 2S1/2 Kusch and Hessel, 1969. |
| 9 | Extended system in the region 8800 - 11500 cm-1; partial analysis. |
| 10 | Unresolved system from 8000 to 8600 cm-1, maximum at 8370 cm-1. |
| 11 | Repulsive curve with small van der Waals minimum. |
| 12 | Average of the constants from B-X and C-X Kusch and Hessel, 1968, Kusch and Hessel, 1969. Also higher order constants. Vibrational levels observed up to v"=100. |
| 13 | Mol. beam magn. reson. 16 |
| 14 | Short extrapolation of ground state vibrational levels Kusch and Hessel, 1969. |
| 15 | Associative ionization of cesium vapour Marr and Wherrett, 1972: see also Popescu, Pascu, et al., 1973. Foster, Leckenby, et al., 1969 give an appearance potential of 3.80 eV, Marr and Wherrett, 1972 recommend 3.68 eV as the most likely value. |
| 16 | eqQ(133Cs) = + 0.23 MHz Logan, Cote, et al., 1952; gJ = 0.00547 μN Brooks, Anderson, et al., 1963. |
| 17 | D00(Cs2) + I.P.(Cs) - I.P.(Cs2); see 15. |
| 18 | Rough estimate from the analysis of charge-exchange cross sections Olson, 1969. Theoretical values tend to be larger Bellomonte, Cavaliere, et al., 1974. |
References
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, NIST Free Links, 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]
McHugh, Eaton, et al., 1989
McHugh, K.M.; Eaton, J.G.; Lee, G.H.; Sarkas, H.W.; Kidder, L.H.; Snodgrass, J.T.; Manaa, M.R.; Bowen, K.H.,
Photoelectron Spectra of the alkali metal cluster Anions: Na-,n=2-5, K-,n=2-7, Rb-,n=2-3, and Cs-,n=2-3,
J. Chem. Phys., 1989, 91, 6, 3792, https://doi.org/10.1063/1.456861
. [all data]
Kappes, Radi, et al., 1985
Kappes, M.M.; Radi, P.; Schar, M.; Schumacher, E.,
Photoionization measurements on dialkali monohalides generated in supersonic nozzle beams,
Chem. Phys. Lett., 1985, 113, 243. [all data]
Helm and Moller, 1983
Helm, H.; Moller, R.,
Bound-free spectroscopy of Cs2+,
Phys. Rev. A:, 1983, 27, 2493. [all data]
Marr and Wherrett, 1972
Marr, G.V.; Wherrett, S.R.,
The ionization of caesium vapour by the method of space charge amplification,
J. Phys. B:, 1972, 5, 1735. [all data]
Foster, Leckenby, et al., 1969
Foster, P.J.; Leckenby, R.E.; Robbins, E.J.,
The ionization potentials of clustered alkali metal atoms,
J. Phys. B:, 1969, 2, 478. [all data]
Creek and Marr, 1968
Creek, D.M.; Marr, G.V.,
Some ultraviolet cross-section measurements on molecular alkali-metal vapours,
J. Quant. Spectrosc. Radiat. Transfer, 1968, 8, 1431. [all data]
Loomis and Kusch, 1934
Loomis, F.W.; Kusch, P.,
The band spectrum of caesium,
Phys. Rev., 1934, 46, 292. [all data]
Ny-Tsi-Ze and Shang-Yi, 1938
Ny-Tsi-Ze, P.; Shang-Yi, C.,
Bandes d'absorption du rubidium et du cesium en presence des gaz etrangers,
J. Phys. Radium, 1938, 9, 5, 169-171. [all data]
Lapp and Harris, 1966
Lapp, M.; Harris, L.P.,
Absorption cross sections of alkali-vapor molecules: I. Cs2 in the visible. II. K2 in the red,
J. Quant. Spectrosc. Radiat. Transfer, 1966, 6, 169. [all data]
Baumgartner, Demtroder, et al., 1970
Baumgartner, G.; Demtroder, W.; Stock, M.,
Lifetime-measurements of alkali-molecules excited by different laserlines,
Z. Phys., 1970, 232, 462. [all data]
Kusch and Loomis, 1936
Kusch, P.; Loomis, F.W.,
Note on a band system of caesium,
Phys. Rev., 1936, 49, 217. [all data]
Kusch and Hessel, 1968
Kusch, P.; Hessel, M.M.,
An analysis of the 6250-Å band system of Cs2,
J. Mol. Spectrosc., 1968, 25, 205. [all data]
Kusch and Hessel, 1969
Kusch, P.; Hessel, M.M.,
A study of the 7667-Å band system of Cs2; the magnetic rotation spectra of the 7667 and 6250-Å systems,
J. Mol. Spectrosc., 1969, 32, 181. [all data]
Finkelnburg and Hahn, 1938
Finkelnburg, W.; Hahn, O.Th.,
Uber die spektren des zasiummolekuls,
Phys. Z., 1938, 39, 98. [all data]
Bayley, Eberlin, et al., 1968
Bayley, D.S.; Eberlin, E.C.; Simpson, J.H.,
Absorption spectrum of diatomic cesium molecules,
J. Chem. Phys., 1968, 49, 2863. [all data]
Sorokin and Lankard, 1971
Sorokin, P.P.; Lankard, J.R.,
Emission spectra of alkali-metal molecules observed with a heat-pipe discharge tube,
J. Chem. Phys., 1971, 55, 3810. [all data]
Niemax, 1972
Niemax, K.,
Satellites of CsI lines,
Phys. Lett. A, 1972, 38, 141. [all data]
Niemax and Pichler, 1974
Niemax, K.; Pichler, G.,
Asymmetric self-broadening of Cs principal lines,
J. Phys. B:, 1974, 7, 1204. [all data]
Collins, Johnson, et al., 1974
Collins, C.B.; Johnson, B.W.; Mirza, M.Y.; Popescu, D.; Popescu, I.,
Multiphoton ionization of cesium through resonant dissociative states of Cs2,
Phys. Rev. A: Gen. Phys., 1974, 10, 813. [all data]
Collins, Johnson, et al., 1973
Collins, C.B.; Johnson, B.W.; Popescu, D.; Musa, G.; Pascu, M.L.; Popescu, I.,
Multiphoton ionization of molecular cesium with a tunable dye laser,
Phys. Rev. A: Gen. Phys., 1973, 8, 2197. [all data]
Granneman, Klewer, et al., 1976
Granneman, E.H.A.; Klewer, M.; Nygaard, K.J.; van der Wiel, M.J.,
Two-photon ionization of Cs2, Rb2 and RbCs using an Ar-ion laser,
J. Phys. B:, 1976, 9, 865. [all data]
Popescu, Pascu, et al., 1973
Popescu, D.; Pascu, M.L.; Collins, C.B.; Johnson, B.W.; Popescu, I.,
Use of space-charge-amplification techniques in the absorption spectroscopy of Cs and Cs2,
Phys. Rev. A: Gen. Phys., 1973, 8, 1666. [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]
Brooks, Anderson, et al., 1963
Brooks, R.A.; Anderson, C.H.; Ramsey, N.F.,
Rotational magnetic moments of diatomic alkalis,
Phys. Rev. Lett., 1963, 10, 441. [all data]
Olson, 1969
Olson, R.E.,
Determination of the difference potential from resonant charge-exchange total cross sections: analysis of Rb+-Rb and Cs+-Cs,
Phys. Rev., 1969, 187, 153. [all data]
Bellomonte, Cavaliere, et al., 1974
Bellomonte, L.; Cavaliere, P.; Ferrante, G.,
Alkali molecular ion energies and expectation values in a model-potential treatment,
J. Chem. Phys., 1974, 61, 3225. [all data]
Notes
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- Symbols used in this document:
EA Electron affinity S°gas,1 bar Entropy of gas at standard conditions (1 bar) ΔfH°gas Enthalpy of formation of gas at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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