Arsenic dimer

Formula: As₂
Molecular weight: 149.84320
CAS Registry Number: 23878-46-8
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Constants of diatomic molecules

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

Data collected through January, 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 ⁷⁵As₂
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
N	(72137)	[319]									N ← X	72082
N	↳Donovan and Strachan, 1971
M	(69607)	[365]									M ← X	69575
M	↳Donovan and Strachan, 1971
J											J ← X	66133
	↳Donovan and Strachan, 1971
											J ← X	66015
	↳Donovan and Strachan, 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
I											I ← X	66542
	↳Donovan and Strachan, 1971
											I ← X	65308
	↳Donovan and Strachan, 1971
H	(61726)	[364] H									H ← X 1 R	61694 H
H	↳Donovan and Strachan, 1971
Unclassified absorption bands in the region 47000 - 55000 cm^-1.
↳Topouzkhanian and Sibai, 1972
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
G	(54586)	[377] 2 H									G ← X 3 R	54560 H
G	↳Donovan and Strachan, 1971; Topouzkhanian and Sibai, 1972
F	(52221)	[386] H									F ← X 4 R	52200 H
F	↳Donovan and Strachan, 1971; Topouzkhanian and Sibai, 1972
Fragments of other electronic states in the region 42400 - 44500 cm^-1.
↳Sibai, Perdigon, et al., 1974
b (³Π_u) 5											b → X R	42006
b (³Π_u) 5	↳Almy and Kinzer, 1935; Almy, 1937; Kinzer and Almy, 1937
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
B ¹Σ_u⁺	(40925)	[243.6] 6 Z			[0.0712] 6					[2.5]	B ↔ X R	40832.2 Z
B ¹Σ_u⁺	↳Gibson and Macfarlane, 1934; Almy and Kinzer, 1935; missing citation; Perdigon and d'Incan, 1970; Perdigon, Martin, et al., 1970; Martin, Perdigon, et al., 1974
A ¹Σ_u⁺	(40349)	[260.3] 7 8 Z			[0.07202] 7 8					[2.50]	A ↔ X R	40265 Z
A ¹Σ_u⁺	↳Gibson and Macfarlane, 1934; Almy and Kinzer, 1935; missing citation; Perdigon and d'Incan, 1970; Perdigon, Martin, et al., 1970; Topouzkhanian and Sibai, 1972; Martin, Perdigon, et al., 1974; Sibai, Perdigon, et al., 1974; Martin, Figuet, et al., 1975
d (³Π_g) 1_g	30818.8	336.7 H	1.36		0.09222	0.00033				2.209₀	d → c 9 V	16185.6 H
	↳missing citation; missing citation; Perdigon and d'Incan, 1970
											d → c 9 V	16348.4 H
	↳missing citation; missing citation; Perdigon and d'Incan, 1970
											d → X	30772.4 H
	↳missing citation; Perdigon and d'Incan, 1970
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^-) 0_u⁺	24641.2	337.0 H	0.83		0.08664	0.00030				2.279₀	(a → c) 10 V	(10100)
	↳missing citation
											a → X 11 R	24595 H
	↳missing citation; Perdigon and d'Incan, 1970
e	19914.7	330.0 H	0.9								e → X R	19865 12 H
e	↳Perdigon and d'Incan, 1970
c ³Σ_u⁺ 0_u^-	14644.4	314.3 H	1.17		0.08491	0.00035				2.302₁
c ³Σ_u⁺ 0_u^-	↳Perdigon and d'Incan, 1970
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 ³Σ_u⁺ 1_u	14481.6	314.3 H	1.17		0.08471 13	0.00035				2.303₆	c(1_u) → X R	14424
c ³Σ_u⁺ 1_u	↳Perdigon and d'Incan, 1970
X ¹Σ_g⁺	0	429.55 H	1.117 14	0.000139	0.10179	0.000333	-0.00000028			2.1026

Notes

System G ← X of Donovan and Strachan, 1971.

Bands with v' ≥ 3 are diffuse.

System E ← X of Donovan and Strachan, 1971.

System f ← X of Donovan and Strachan, 1971.

Only v=0 observed.

Additional ΔG(v+1/2) and B_v values (v≤17) in Martin, Perdigon, et al., 1974. Strong perturbations.

Additional ΔG(v+1/2) and B_v values (v≤17) in Martin, Perdigon, et al., 1974, Sibai, Perdigon, et al., 1974, Martin, Figuet, et al., 1975. Strong perturbations produced by interaction with the B and, possibly, other states.

In emission no bands with v' ≥ 10 are observed except those with v'= 14 Almy and Kinzer, 1935. In absorption bands with v' ≥ 10 are observed Topouzkhanian and Sibai, 1972, Sibai, Perdigon, et al., 1974 but the lines in them are broad except those with v'= 14 which are sharp. The line width varies greatly as a function of J in bands with v' ≥ 10. There is clearly a predissociation limit at 42700 ± 100 cm^-1.

Originally Kinzer and Almy, 1937 attributed to As₂⁺. Recognized as being due to neutral As₂ by Mrozowski and Santaram, 1967. The lower states are the two case "c" components of c ³Σ_u⁺ Perdigon and d'Incan, 1970.

Strong system in the infrared Mrozowski and Santaram, 1967, not analyzed in detail.

System D → X of Kinzer and Almy, 1937.

19855 in Perdigon and d'Incan, 1970 appears to be erroneous.

Ω-type doubling, Δν_fe = (-)0.00018J(J+1).

ω_ez_e = -0.00001958.

From the predissociation limit in A ¹Σ_u⁺ assuming dissociation into ⁴S + ²D without kinetic energy Kinzer and Almy, 1937. Extrapolation of the ground state vibrational levels (observed to v=70, i.e., 80% of D₀⁰ ) gives 3.93 eV Almy, 1937 Kinzer and Almy, 1937.

References

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Donovan and Strachan, 1971
Donovan, R.J.; Strachan, P., Vacuum U.-V. spectra of transient molecules and radicals, J. Chem. Soc. Faraday Trans., 1971, 67, 3407. [all data]

Topouzkhanian and Sibai, 1972
Topouzkhanian, A.; Sibai, A.M., Spectres d'absorption dans l'ultraviolet du vide de vapeurs d'arsenic diatomique, Spectrochim. Acta, 1972, 28, 2197. [all data]

Sibai, Perdigon, et al., 1974
Sibai, A.M.; Perdigon, P.; Topouzkhanian, A., Absorption spectrum of As₂. Further analysis of the A → X system and observation of new electronic states, Z. Naturforsch. A, 1974, 29, 429. [all data]

Almy and Kinzer, 1935
Almy, G.M.; Kinzer, G.D., The emission spectrum of diatomic arsenic, Phys. Rev., 1935, 47, 721. [all data]

Almy, 1937
Almy, G.M., Spectra of diatomic molecules of elements of the fifth group, J. Phys. Chem., 1937, 41, 47. [all data]

Kinzer and Almy, 1937
Kinzer, G.D.; Almy, G.M., The emission spectrum of diatomic arsenic. II, Phys. Rev., 1937, 52, 814. [all data]

Gibson and Macfarlane, 1934
Gibson, G.E.; Macfarlane, A., The absorption spectrum of arsenic, Phys. Rev., 1934, 46, 1059. [all data]

Perdigon and d'Incan, 1970
Perdigon, P.; d'Incan, J., Le spectre electronique de la molecule As₂, Can. J. Phys., 1970, 48, 1140. [all data]

Perdigon, Martin, et al., 1970
Perdigon, P.; Martin, F.; d'Incan, J., The mutual perturbations of A¹Σ_u⁺ (v = 2) and B¹Σ_u⁺ (v = 0) levels of As₂ molecule, J. Mol. Spectrosc., 1970, 36, 341. [all data]

Martin, Perdigon, et al., 1974
Martin, F.; Perdigon, P.; d'Incan, J., An extensive rotational analysis of A → X and B → X systems in the emission spectrum of As₂ molecule, J. Mol. Spectrosc., 1974, 50, 45. [all data]

Martin, Figuet, et al., 1975
Martin, F.; Figuet, J.; Perdigon, P., Evidence for bands arising from A¹Σ_u⁺ (v = 3) level in the spectrum of As₂, J. Mol. Spectrosc., 1975, 57, 319. [all data]

Mrozowski and Santaram, 1967
Mrozowski, S.; Santaram, C., Electronic spectra of P₂, As₂, and Sb₂ molecules, J. Opt. Soc. Am., 1967, 57, 522. [all data]

Notes

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Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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