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
The 3d structure may be viewed using Java or Javascript.
Permanent link for this species. Use this link for bookmarking this species for future reference.
Information on this page:
Other data available:
- Gas phase thermochemistry data
Data at other public NIST sites:
- Gas Phase Kinetics Database
Options:
- Switch to calorie-based units

Gas phase ion energetics data

Go To: Top, Constants of diatomic molecules, References, Notes

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

Go To: Top, Gas phase ion energetics data, References, Notes

Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through October, 1976

Symbols used in the table of constants
Symbol	Meaning
State	electronic state and / or symmetry symbol
T_e	minimum electronic energy (cm^-1)
ω_e	vibrational constant – first term (cm^-1)
ω_ex_e	vibrational constant – second term (cm^-1)
ω_ey_e	vibrational constant – third term (cm^-1)
B_e	rotational constant in equilibrium position (cm^-1)
α_e	rotational constant – first term (cm^-1)
γ_e	rotation-vibration interaction constant (cm^-1)
D_e	centrifugal distortion constant (cm^-1)
β_e	rotational constant – first term, centrifugal force (cm^-1)
r_e	internuclear distance (Å)
Trans.	observed transition(s) corresponding to electronic state
ν₀₀	position of 0-0 band (units noted in table)

Diatomic constants for ¹³³Cs₂
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	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
(E) 3	↳missing citation; Lapp and Harris, 1966; Baumgartner, Demtroder, et al., 1970
D 4											D ← X
D 4	↳Loomis and Kusch, 1934; Lapp and Harris, 1966
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
C (¹Π_u) 1_u	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 V_R	15942.45 (Z)
C (¹Π_u) 1_u	↳missing citation; Kusch and Loomis, 1936; Kusch and Hessel, 1968
B (¹Π_u) 1_u	13043.88	34.329 8 H	0.0800 8								B ← X R	13040.03 H
B (¹Π_u) 1_u	↳missing citation; Kusch and Hessel, 1969
A (¹Σ⁺_u) 9											A ↔ X R
A (¹Σ⁺_u) 9	↳Loomis and Kusch, 1934; Finkelnburg and Hahn, 1938; Bayley, Eberlin, et al., 1968; Sorokin and Lankard, 1971
b (³Π_u) 10											b ↔ X
b (³Π_u) 10	↳Bayley, Eberlin, et al., 1968; Sorokin and Lankard, 1971
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
a ³Σ_u⁺	(3140) 11
X ²Σ_g⁺	0	42.022 12	0.0823 12		0.0127₁ 6	0.0000264		4.64E-09 6		4.47 13

Notes

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.

Intermediates in the two-photon ionization of Cs₂ Collins, Johnson, et al., 1973, Granneman, Klewer, et al., 1976.

Strong system in the region 19140 - 21700, maximum at 20800 cm^-1.

Weak system in the region 16500 - 18000 cm^-1.

ω_e,...,ω_ez_e 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.

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.

See 6.

ω_e,...,ω_ez_e 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 ²P_3/2 + 6 ²S_1/2 Kusch and Hessel, 1969.

Extended system in the region 8800 - 11500 cm^-1; partial analysis.

Unresolved system from 8000 to 8600 cm^-1, maximum at 8370 cm^-1.

Repulsive curve with small van der Waals minimum.

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.

Mol. beam magn. reson. 16

Short extrapolation of ground state vibrational levels Kusch and Hessel, 1969.

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.

eqQ(¹³³Cs) = + 0.23 MHz Logan, Cote, et al., 1952; g_J = 0.00547 μ_N Brooks, Anderson, et al., 1963.

D₀⁰(Cs₂) + I.P.(Cs) - I.P.(Cs₂); see 15.

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 ion energetics data, Constants of diatomic molecules, Notes

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

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

Symbols used in this document:

EA Electron affinity
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
Customer support for NIST Standard Reference Data products.