tritium

Formula: T₂
Molecular weight: 6.0320985554
IUPAC Standard InChI: InChI=1S/H2/h1H/i1+2T
IUPAC Standard InChIKey: UFHFLCQGNIYNRP-JMRXTUGHSA-N
CAS Registry Number: 10028-17-8
Chemical structure:
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Constants of diatomic molecules

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

Data collected through November, 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 T₂
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 ³Π_u 5pπ	(120984.₃)	1348.89	22.52		10.021	0.294		0.0022		1.0562	n → a R	24923.03
n ³Π_u 5pπ	↳Cunningham and Dieke, 1950
k ³Π_u 4pπ	(118403.₂)	1355.39	22.026 1	0.133	10.053	0.296		0.0022		1.0545	k → a R	22345.34
k ³Π_u 4pπ	↳Cunningham and Dieke, 1950
f ³Σ_u⁺ 4pσ	(116653)	[1278]			9.90	0.30				1.063	f → a R	20561.9
f ³Σ_u⁺ 4pσ	↳Cunningham and Dieke, 1950
d ³Π_u 3pπ	(112736.₀)	1372.11	22.135 2	0.159	10.150 3	0.3050 3	0.0038	0.00217 4	-0.000065	1.0494	d → a R	16686.4₄
d ³Π_u 3pπ	↳Dieke and Tomkins, 1949
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
e ³Σ_u⁺ 3pσ	(107770.₈)	1272.28	23.03 5	0.17	9.2056	0.2803	-0.00156	0.1887	-0.000045	1.1019₇	e → a R	11671.06
e ³Σ_u⁺ 3pσ	↳Dieke and Tomkins, 1951
a ³Σ_g⁺ 2sσ	(95965.₄) 6	1541.57	24.47 7	0.312	11.4374	0.3258 8				0.98862	(a-x)	(95464.4) 9
b ³Σ_u⁺ 2pσ 10											a → b
F ¹Σ_g⁺ 2pσ²	(100935.₉) 11	[706.0] 12			B₈=2.5₀ 13					r₈=2.11	F → B R	14
F ¹Σ_g⁺ 2pσ²	↳Dieke and Cunningham, 1965
E ¹Σ_g⁺ 2sσ	(100136.₇)	1454.18	30.52		10.9306	0.3659		0.2403		1.0112₈	E → B V	8765.40
E ¹Σ_g⁺ 2sσ	↳Dieke and Cunningham, 1965
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 2pπ	(100099.₇) 6										(C-X)	(99536.₉) 15
B ¹Σ_u⁺ 2pσ	(91696.₃) 6	787.28 16	7.013 16		6.716 17	0.207₆ 17	0.0072	0.17₃ 17	-0.0008	1.290₁	(B-X)	(90825.₀) 18
X ¹Σ_g⁺ 1sσ²	0	2546.4₇ 19	41.23 19		20.335 19	0.5887 20				(0.74142)
X ¹Σ_g⁺ 1sσ²	↳Cashion, 1966

Notes

missing note

ω_ez_e = -0.002.

The rotational constants refer to ³Π^-; ³Π⁺ is perturbed. The Λ-type doubling is somewhat irregular.

missing note

ω_ez_e = -0.0204.

From the T_e values of H₂ and D₂ assuming that the electronic isotope shift is proportional to (1 - μ_H2/μ_T2).

ω_ez_e = -0.016.

missing note

From T_e assuming Y₀₀ (a ³Σ_g⁺) = 0 but taking account of Y₀₀ in the ground state X ¹Σ_g⁺ (see 19).

Repulsive state, lower state of T₂ continuum.

From the observed v₈₀ and the energy of v=8 above the outer minimum of the E,F double-minimum state as calculated by Kolos and Wolniewicz, 1969.

Calculated ΔG(1/2) value for the outer minimum Kolos and Wolniewicz, 1969.

Vibrational numbering of Kolos and Wolniewicz, 1969. The D₈ value is large and negative. For higher vibrational levels (above the potential maximum) B_v is larger, e.g. Dieke and Cunningham, 1965 give B₁₃ = 3.892 Dieke and Cunningham, 1965, and D₁₃ = 0.00109 has the normal sign, in agreement with the fact that for these levels the vibrational motion covers both minima of the E,F state. v=0...7 levels not yet observed.

According to Kolos and Wolniewicz, 1969 the lowest level of the outer minimum is expected at 9204.5 cm^-1 above B ¹Σ_u⁺(v=0). The v=8 level lies just below the potential maximum.

From T_e and the zero-point energy calculated by Kolos and Wolniewicz, 1968.

From the R(0) lines in the E,F-B system Dieke and Cunningham, 1965: ω_ey_e = +0.0912 Dieke and Cunningham, 1965. The zero-point energy (Y₀₀ = 2.6 included) is 394.4₆ cm^-1.

From combination differences formed from the data on E,F-B Dieke and Cunningham, 1965; β_e = -0.0008.

From the calculated T_e and the zero-point energies as given in 16 and 19.

Calculated by Cashion, 1966 from the potential function of Kolos and Wolniewicz, 1965 and based on v = 0...3 only: experimental values are not available. The zero-point energy (Y₀₀ = 2.8 included) is 1265.7₄ cm^-1.

α_v= +0.0053(v+1/2)² - 0.00018(v+1/2)³; see 19.

D₀₀= 37028.4 cm^-1 Kolos and Wolniewicz, 1968, 2, calculated from ab initio potential function Kolos and Wolniewicz, 1968, 2; non- adiabatic corrections which are certainly less than +0.2 cm^-1 and Lamb shift corrections (~ 0.2 cm^-1) are not included. No observed value is available yet.

From the theoretical values of D₀₀(T₂) and D₀₀(T₂⁺), and I.P.(T).

References

Go To: Top, Constants of diatomic molecules, Notes

Cunningham and Dieke, 1950
Cunningham; Dieke, Johns Hopkins University, Department of Physics, Rpt. NYO-692, 1950, 1. [all data]

Dieke and Tomkins, 1949
Dieke, G.H.; Tomkins, F.S., The molecular spectrum of hydrogen. The Fulcher bands of TH and T₂, Phys. Rev., 1949, 76, 283. [all data]

Dieke and Tomkins, 1951
Dieke, G.H.; Tomkins, F.S., The 3p³Σ→2s³Σ-bands of TH and T₂, Phys. Rev., 1951, 82, 796. [all data]

Dieke and Cunningham, 1965
Dieke, G.H.; Cunningham, S.P., Bands of D₂ and T₂ originating from the lowest excited ¹Σ_g states (1sσ)(2sσ)¹Σ_g and (2pσ)²¹Σ_g, J. Mol. Spectrosc., 1965, 18, 288. [all data]

Cashion, 1966
Cashion, J.K., Properties of the ¹Σ_g⁺ state of H₂ calculated from an accurate adiabatic potential, J. Chem. Phys., 1966, 45, 1037. [all data]

Kolos and Wolniewicz, 1969
Kolos, W.; Wolniewicz, L., Theoretical investigation of the lowest double-minimum state E, F¹Σ_g⁺ of the hydrogen molecule, J. Chem. Phys., 1969, 50, 3228. [all data]

Kolos and Wolniewicz, 1968
Kolos, W.; Wolniewicz, L., Vibrational and rotational energies of the B¹Σ_u⁺, C¹Π_u, C¹Π_u, and a³Σ_g⁺ states of the hydrogen molecule, J. Chem. Phys., 1968, 48, 3672. [all data]

Kolos and Wolniewicz, 1965
Kolos, W.; Wolniewicz, L., Potential-energy curves for the X¹Σ_g⁺, b³Σ_u⁺, and C¹Π_u states of the hydrogen molecule, J. Chem. Phys., 1965, 43, 2429. [all data]

Kolos and Wolniewicz, 1968, 2
Kolos, W.; Wolniewicz, L., Improved theoretical ground-state energy of the hydrogen molecule, J. Chem. Phys., 1968, 49, 404. [all data]

Notes

Go To: Top, Constants of diatomic molecules, References

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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