Line strengths of N2O and its rare isotopic derivatives have been measured in the 1120–1440-cm−1 spectral region. The spectra were obtained at low sample pressure and high resolution (0.0054 cm−1), and the data are analyzed to determine band strengths, rotationless dipole moment matrix elements, and F factor coefficients for the various bands. First-order nondegenerate perturbation theory was used to derive explicit expressions for the rotationless dipole moment matrix elements and F factor coefficients, and from this derivation, general expressions for the F factor are obtained: F = [1 + a1m + a2J′(J′ + 1) + a3J″(J″ + 1)]2 for Δl = 0, ±1 bands and F = (1 + a1m)2 · H for Δl = ±2, ±3 bands, where H is given to good approximation for |Δl| = 2 bands as H = [J′(J′ + 1)]2. These F factor expressions are applied in the analysis of the experimental data from which the vibrational band strength of the forbidden band 0220(e)–0000 was found to be (5.69 ± 0.26) × 10−8 cm−2/atm at 296 K. The theoretical results can also be applied to CO2 line strengths.
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Isotopic Abundances, Vibrational (Qv), and Rotational(QR) Partition Functions of N2O at 296 K.
Molecule
Abundance %
Qv
QR
446
99.02
1.127
491
456
0.365
1.136
491
546
0.365
1.130
508
448
0.204
1.131
520
Molecule notation is 446 = 14N216O, 456 14N15N16O, etc.
Table II
Vibrational Transitions V1–V2 and Interacting States Which are Applicable for Evaluating the Rotationless Dipole Moment Matrix Element R12 and F Factor coefficients of N2O and CO2 Bands; Vibrational State Notation of N2O is used with K = |l| and ΔK = K2 − K1.
Not all bands allowed for the symmetric CO2 molecule.
J dependent Fermi-type resonant interaction between levels of the 1001 and 0600 states and 1001 and 0620 states of N2O.
J dependent Coriolis–type resonant Interaction between levels in the 0311(e) and 3000 states of 13C16O2.
Table III
σ* Obtained from Least-Squares Fitting of the Measured N2O Line Strength Values to Various Forms of the F Factor.
Applies to either e′–e″ or f′–f″ transitions.
The numbers in parentheses are the uncertainties on the last digit. Band centers in cm−1.
Table V
Observed Line Positions and Observed and Calculated* Line Strengths in the 0220(e)–0000 Band of N2O; Strengths in cm−2/atm at 296 K.
Line
Position obs.(cm−1)
Strength
obs.
o–c%
P58
1133.4682
6.80E−05
1.8
P57
1134.1415
7.70E−05
−0.7
P56
1134.8186
8.90E−05
−0.5
P54
1136.1832
1.13E−04
−3.4
P53
1136.8716
1.25E−04
−5.8
P52
1137.5627
1.41E−04
−6.0
P50
1138.9564
1.87E−04
0.1
P49
1139.6586
2.05E−04
−1.0
P44
1143.2218
3.20E−04
2.0
P43
1143.9447
3.40E−04
1.7
P42
1144.6711
3.50E−04
−1.1
P38
1147.6086
4.20E−04
1.6
P36
1149.0966
4.15E−04
−2.9
P35
1149.8451
4.50E−04
4.8
P34
1150.5969
4.60E−04
7.5
P32
1152.1093
4.50E−04
8.7
P31
1152.8699
4.15E−04
3.3
P29
1154.4001
3.90E−04
6.0
P26
1156.7159
2.90E−04
−2.7
P24
1158.2740
2.52E−04
3.0
P19
1162.2150
1.18E−04
1.1
P18
1163.0110
9.50E−05
−0.7
P17
1163.8090
7.60E−05
−1.2
P15
1165.4133
4.70E−05
1.4
R12
1188.8423
3.50E−05
−4.2
R13
1189.7114
5.20E−05
4.6
R16
1192.3337
9.60E−05
10.3
R17
1193.2127
1.23E−04
−6.8
R18
1194.0940
1.55E−04
−3.2
R23
1198.5359
3.30E−04
0.0
R24
1199.4318
3.60E−04
−1.7
R25
1200.3301
4.10E−04
2.1
R26
1201.2313
4.40E−04
1.1
R28
1203.0405
4.80E−04
−3.1
R29
1203.9492
5.10E−04
−2.1
R30
1204.8606
5.60E−04
3.2
R31
1205.7746
5.70E−04
1.8
R32
1206.6914
5.80E−04
1.3
R33
1207.6108
5.80E−04
−0.1
R34
1208.5330
5.95E−04
1.9
R35
1209.4581
5.75E−04
−1.3
R36
1210.3859
6.00E−04
4.0
R37
1211.3166
5.80E−04
2.4
R38
1212.2501
6.00E−04
8.6
R39
1213.1867
5.50E−04
2.8
R40
1214.1262
5.00E−04
−2.7
R41
1215.0685
4.90E−04
−0.1
R42
1216.0138
4.70E−04
1.1
R43
1216.9621
4.40E−04
0.5
R44
1217.9134
3.90E−04
−4.8
R45
1218.8678
3.85E−04
1.1
R57
1230.5652
9.90E−05
0.5
R61
1234.5663
5.00E−05
−4.5
R63
1236.5861
4.05E−05
9.6
Calculated values are computed from parameters obtained from least-squares fit of the experimental values
Note: o–c% are from the expression, [(Sobs−Scal)/Scal] × 100.
Tables (5)
Table I
Isotopic Abundances, Vibrational (Qv), and Rotational(QR) Partition Functions of N2O at 296 K.
Molecule
Abundance %
Qv
QR
446
99.02
1.127
491
456
0.365
1.136
491
546
0.365
1.130
508
448
0.204
1.131
520
Molecule notation is 446 = 14N216O, 456 14N15N16O, etc.
Table II
Vibrational Transitions V1–V2 and Interacting States Which are Applicable for Evaluating the Rotationless Dipole Moment Matrix Element R12 and F Factor coefficients of N2O and CO2 Bands; Vibrational State Notation of N2O is used with K = |l| and ΔK = K2 − K1.
Not all bands allowed for the symmetric CO2 molecule.
J dependent Fermi-type resonant interaction between levels of the 1001 and 0600 states and 1001 and 0620 states of N2O.
J dependent Coriolis–type resonant Interaction between levels in the 0311(e) and 3000 states of 13C16O2.
Table III
σ* Obtained from Least-Squares Fitting of the Measured N2O Line Strength Values to Various Forms of the F Factor.
Applies to either e′–e″ or f′–f″ transitions.
The numbers in parentheses are the uncertainties on the last digit. Band centers in cm−1.
Table V
Observed Line Positions and Observed and Calculated* Line Strengths in the 0220(e)–0000 Band of N2O; Strengths in cm−2/atm at 296 K.
Line
Position obs.(cm−1)
Strength
obs.
o–c%
P58
1133.4682
6.80E−05
1.8
P57
1134.1415
7.70E−05
−0.7
P56
1134.8186
8.90E−05
−0.5
P54
1136.1832
1.13E−04
−3.4
P53
1136.8716
1.25E−04
−5.8
P52
1137.5627
1.41E−04
−6.0
P50
1138.9564
1.87E−04
0.1
P49
1139.6586
2.05E−04
−1.0
P44
1143.2218
3.20E−04
2.0
P43
1143.9447
3.40E−04
1.7
P42
1144.6711
3.50E−04
−1.1
P38
1147.6086
4.20E−04
1.6
P36
1149.0966
4.15E−04
−2.9
P35
1149.8451
4.50E−04
4.8
P34
1150.5969
4.60E−04
7.5
P32
1152.1093
4.50E−04
8.7
P31
1152.8699
4.15E−04
3.3
P29
1154.4001
3.90E−04
6.0
P26
1156.7159
2.90E−04
−2.7
P24
1158.2740
2.52E−04
3.0
P19
1162.2150
1.18E−04
1.1
P18
1163.0110
9.50E−05
−0.7
P17
1163.8090
7.60E−05
−1.2
P15
1165.4133
4.70E−05
1.4
R12
1188.8423
3.50E−05
−4.2
R13
1189.7114
5.20E−05
4.6
R16
1192.3337
9.60E−05
10.3
R17
1193.2127
1.23E−04
−6.8
R18
1194.0940
1.55E−04
−3.2
R23
1198.5359
3.30E−04
0.0
R24
1199.4318
3.60E−04
−1.7
R25
1200.3301
4.10E−04
2.1
R26
1201.2313
4.40E−04
1.1
R28
1203.0405
4.80E−04
−3.1
R29
1203.9492
5.10E−04
−2.1
R30
1204.8606
5.60E−04
3.2
R31
1205.7746
5.70E−04
1.8
R32
1206.6914
5.80E−04
1.3
R33
1207.6108
5.80E−04
−0.1
R34
1208.5330
5.95E−04
1.9
R35
1209.4581
5.75E−04
−1.3
R36
1210.3859
6.00E−04
4.0
R37
1211.3166
5.80E−04
2.4
R38
1212.2501
6.00E−04
8.6
R39
1213.1867
5.50E−04
2.8
R40
1214.1262
5.00E−04
−2.7
R41
1215.0685
4.90E−04
−0.1
R42
1216.0138
4.70E−04
1.1
R43
1216.9621
4.40E−04
0.5
R44
1217.9134
3.90E−04
−4.8
R45
1218.8678
3.85E−04
1.1
R57
1230.5652
9.90E−05
0.5
R61
1234.5663
5.00E−05
−4.5
R63
1236.5861
4.05E−05
9.6
Calculated values are computed from parameters obtained from least-squares fit of the experimental values
Note: o–c% are from the expression, [(Sobs−Scal)/Scal] × 100.