Home Symbol which looks like a small house Up Solid circle with an upward pointer in it


Data at NIST subscription sites:

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase thermochemistry data

Go To: Top, Constants of diatomic molecules, NIST Free Links, 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
Deltafgas89.701kcal/molReviewChase, 1998Data last reviewed in June, 1977
Quantity Value Units Method Reference Comment
gas,1 bar44.751cal/mol*KReviewChase, 1998Data last reviewed in June, 1977

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. - 1300.1300. - 6000.
A 6.6680418.316910
B -0.3151270.437737
C 2.615321-0.060343
D -1.1128910.003964
E 0.017360-0.928873
F 87.7635085.41709
G 52.9052152.65631
H 89.7001089.70010
ReferenceChase, 1998Chase, 1998
Comment Data last reviewed in June, 1977 Data last reviewed in June, 1977

Constants of diatomic molecules

Go To: Top, Gas phase thermochemistry data, NIST Free Links, 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 March, 1977

Symbols used in the table of constants
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 14ND
d 1Sigma+ 83168 1953.7 Z 38.2  7.693 0.257 1 .0033 [4.81E-4] 1  1.1156 d rarrow c V 39484.22 Z
missing citation; Graham and Lew, 1978
           d rarrow b R 61721.5 (Z)
Whittaker, 1969
c 1Pi 43786 1756.5 Z 50.95 -10.37 7.833 2 3 0.379 4 -0.047 4 [6.07E-4] 5  1.1055 c rarrow b R 22237.31 Z
missing citation
           c lrarrow a 6 R 30849.06 Z
Dieke and Blue, 1934; Florent and Leach, 1952; missing citation; missing citation
A 3Pii 29820 7 2361 8 53 8  [8.7575] 9 0.2829 10 -0.0033 [5.087E-4] 9  1.0372 A lrarrow X 11 29798.75 Z
missing citation; Kopp, Kronekvist, et al., 1965; Shimauchi, 1966; Shimauchi, 1967; missing citation
b 1Sigma+ 21198 [2371.81] Z 38.8 12  8.9472 0.2383  4.64E-4  1.0344 b rarrow X 11 21225 Z
Gilles, Masanet, et al., 1974
a 1Delta (12596) [2356.17] Z (36) 13  8.9542 0.2427  [4.838E-4] 14  1.0340 (a-X) 12613 15
X 3Sigma- 0 2398 8 42 8  [8.7913] 16 0.2531 17  [4.904E-4] 16  1.03612 18  
Wayne and Radford, 1976


1gammae=+0.0033 (v=0,1,2), B3 = 6.864; D1,2,3(E-4 cm-1)= 4.50, 4.51, 12 Graham and Lew, 1978; H0= +2.49E-8 Graham and Lew, 1978.
2Lambda-type doubling Delta vef(v=0) = +0.00436J(J+1) Whittaker, 1967, Graham and Lew, 1978, and increasing with v Whittaker, 1967, Graham and Lew, 1978.
3Predissociation by rotation in v=0... 3 above J=30, 25, 18, 5, respectively Graham and Lew, 1978.
4gammae=-0.047 (v2); B3 =5.803 Graham and Lew, 1978.
5D1,2,3(E-4 cm-1)= 6.49, 8.06, 27; H0,1,2(E-8 cm-1)= -4.0, -13.2, -38.5.
6Observed in absorption by Bollmark, Kopp, et al., 1970 in the flash photolysis of DN3.
7A0 = -34.58; from Veseth, 1972 who gives additional multiplet splitting constants. See also Kovacs and Korwar, 1970.
8Calculated from the constants for NH. The origins of the A lrarrow X 1-1 and 2-2 bands are at 29738.42 and 29658.19 cm-1 .
9"True" constants calculated by Veseth, 1972 from the data of Bollmark, Kopp, et al., 1970, H0 = +1.57E-8. The Lambda-type doubling parameters were also evaluated by Veseth, 1972. B0(effective) = 8.7610 cm-1 Shimauchi, 1966; for effective Dv, Hv values (v=0,1,2) see Shimauchi, 1966, Shimauchi, 1967.
10alphae and gammae refer to the effective rotational constants of Shimauchi, 1966, Shimauchi, 1967.
11Undegraded 0-0 band.
12Average of two values obtained a) from omegaexe of NH and b) from bandhead measurements and calculated head-origin separations in the drarrowb system.
13From a comparison with DeltaG(1/2) of NH.
14D1 = 4.71E-4, H0 = +2.09E-8.
15v00(b-x) + v00(c-b) - v00(c-a).
16"True" B0 and D0 from Veseth, 1972, H0 = +l.82E-8; multiplet splitting parameters lambda0 ~ +0.895, gamma0 = -0.0061. The evaluation of these constants Veseth, 1972 takes fully into account the 3Pi ~ 3Sigma- interaction and thus gives results that differ considerably from the effective constants Kopp, Kronekvist, et al., 1965, Shimauchi, 1966, Bollmark, Kopp, et al., 1970. The latter are in good agreement with the more precise constants from the laser-magnetic-resonance spectra Wayne and Radford, 1976: B0 = 8.7815, lambda0 = +0.9184, gamma0 = -0.0294. Effective Dv, Hv values in Shimauchi, 1966, Shimauchi, 1967. From the effective Bv values Kopp, Kronekvist, et al., 1965, Shimauchi, 1966, Shimauchi, 1967.
17missing note
18Rotation sp. 20
19From the limiting curve of dissociation in c 1Pi Graham and Lew, 1978; see 3. For NH DeltaG(3/2) = 1694.08. The theoretical calculations of missing citation predict a potential maximum resulting from the avoided crossing of the two 1Pi states arising from N(2D)+H(2S) and N(2P)+H(2S).
20Laser magnetic resonance; hyperfine structure constants.


Go To: Top, Gas phase thermochemistry 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]

Graham and Lew, 1978
Graham, W.R.M.; Lew, H., Spectra of the d1«SIGMA»+-c1«PI» and d1«SIGMA»+-b1«SIGMA»+ systems and dissociation energy of NH and ND, Can. J. Phys., 1978, 56, 85. [all data]

Whittaker, 1969
Whittaker, F.L., Observation of the d1«SIGMA»+ -b1«SIGMA»+ system of NH and ND in the vacuum ultraviolet, Can. J. Phys., 1969, 47, 1291. [all data]

Dieke and Blue, 1934
Dieke, G.H.; Blue, R.W., A1«PI» --> 1«DELTA» band of NH and the corresponding ND band, Phys. Rev., 1934, 45, 395. [all data]

Florent and Leach, 1952
Florent, R.; Leach, S., Contribution a l'etude du spectre d'emission de l'ammoniac et de l'ammoniac lourd: la transition 1«PI»-->1«DELTA» des radicaux NH et ND, J. Phys. Radium, 1952, 13, 377. [all data]

Kopp, Kronekvist, et al., 1965
Kopp, I.; Kronekvist, M.; Aslund, N., On the triplet bands of ND, Ark. Fys., 1965, 30, 9. [all data]

Shimauchi, 1966
Shimauchi, M., Rotational isotope effect in the (A3«PI»i - X3«SIGMA»-) system of NH and ND, Sci. Light (Tokyo), 1966, 15, 161. [all data]

Shimauchi, 1967
Shimauchi, M., Rotational analysis of the (2,2) band of the (A3«PI»i - X3«SIGMA»-) system of ND, Sci. Light (Tokyo), 1967, 16, 185. [all data]

Gilles, Masanet, et al., 1974
Gilles, A.; Masanet, J.; Vermeil, C., Direct determination of the NH b1«SIGMA»+ --> X3«SIGMA»- energy difference, Chem. Phys. Lett., 1974, 25, 346. [all data]

Wayne and Radford, 1976
Wayne, F.D.; Radford, H.E., The laser magnetic resonance spectra of imine (NH) and its isotopes, Mol. Phys., 1976, 32, 1407. [all data]

Whittaker, 1967
Whittaker, F.L., The «DELTA»v=0 sequence in the d1«SIGMA»+ - c1«PI» system of NH and ND, Proc. Phys. Soc. London, 1967, 90, 535. [all data]

Bollmark, Kopp, et al., 1970
Bollmark, P.; Kopp, I.; Rydh, B., Rotational analysis of the ND A 3«PI»i-X3«SIGMA»- (0,0) band, J. Mol. Spectrosc., 1970, 34, 487. [all data]

Veseth, 1972
Veseth, I., Fine structure of 3«PI» and 3«SIGMA»- states in diatomic molecules, J. Phys. B:, 1972, 5, 229. [all data]

Kovacs and Korwar, 1970
Kovacs, I.; Korwar, V.M., On the anomalous multiplet splitting of the triplet terms of the ND molecule, Acta Phys. Acad. Sci. Hung., 1970, 29, 85. [all data]


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