The infrared transmittance of carbon dioxide has been calculated over a wide range of path lengths, pressures, and temperatures from 500 to 10,000 cm−1. Values of the transmittance are given at intervals of 2.5 cm−1. In addition, transmittance values are also given which have been averaged over larger intervals. All contributing spectral lines whose relative intensity is greater than 10−8 that of the strongest line in any particular band have been included in the calculation. In addition, the contributions from the eight major isotopic species have been included. The calculation of the vibrational energy levels included terms through the third power of the vibrational quantum number and also the effects of Fermi resonance. The final transmittance tables were generated using the quasi-random model of molecular band absorption.
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Groups 2 and 3 both correspond to 2 units of Δυ2. They are separated because experimentally they are resolved and measured separately. In addition it is to be noted that the ground-state transition (000,0) → (020,0) corresponding to two units of Δυ2 is forbidden by the selection rules for the main isotopic species which is symmetric. Thus it is not listed as a primary transition even though it occurs for the rarer asymmetric species.
Groups 4 and 5 correspond to 3 units of Δυ2. They are separated because they are resolved experimentally.
These groups list only one primary transition. However, there are other ground-state transitions in Fermi resonance with the one listed which might equally well have been listed. For example, group 14 actually has a primary quintuplet (000,0) → (081,0), (161,0), (241,0), (321,0), (401,0) in addition to the transition (000,0) → (003,0). There are additional ground-state transitions for the asymmetric species.
The relative intensities of these transitions were not given by Yamamoto and Sasamori12 but were determined on the basis of the distribution of intensities within Fermi resonance groups as discussed in the text.
Table IV
Normalization Constants
Transition group no.
(300°K) [cm−1 (atm-cm)−1]
1
6.9 × 10−1
2
2.0 × 10−2
3
5.0 × 10−2
4
6.3 × 10−5
5
6.4 × 10−4
6
8.4
7
7.0 × 10−7
8
2.6 × 10−1
9
7.0 × 10−10
10
3.9 × 10−3
11
7.0 × 10−13
12
6.8 × 10−5
13
7.0 × 10−16
14
1.7 × 10−4
15
7.0 × 10−19
16
3.6 × 10−7
17
7.0 × 10−22
18
1.2 × 10−8
19
7.0 × 10−25
20
5.0 × 10−10
21
7.0 × 10−28
22
2.0 × 10−11
Table V
Transmittance at 1-Atm Pressure Averaged over 50 cm−1 Intervals
Groups 2 and 3 both correspond to 2 units of Δυ2. They are separated because experimentally they are resolved and measured separately. In addition it is to be noted that the ground-state transition (000,0) → (020,0) corresponding to two units of Δυ2 is forbidden by the selection rules for the main isotopic species which is symmetric. Thus it is not listed as a primary transition even though it occurs for the rarer asymmetric species.
Groups 4 and 5 correspond to 3 units of Δυ2. They are separated because they are resolved experimentally.
These groups list only one primary transition. However, there are other ground-state transitions in Fermi resonance with the one listed which might equally well have been listed. For example, group 14 actually has a primary quintuplet (000,0) → (081,0), (161,0), (241,0), (321,0), (401,0) in addition to the transition (000,0) → (003,0). There are additional ground-state transitions for the asymmetric species.
The relative intensities of these transitions were not given by Yamamoto and Sasamori12 but were determined on the basis of the distribution of intensities within Fermi resonance groups as discussed in the text.
Table IV
Normalization Constants
Transition group no.
(300°K) [cm−1 (atm-cm)−1]
1
6.9 × 10−1
2
2.0 × 10−2
3
5.0 × 10−2
4
6.3 × 10−5
5
6.4 × 10−4
6
8.4
7
7.0 × 10−7
8
2.6 × 10−1
9
7.0 × 10−10
10
3.9 × 10−3
11
7.0 × 10−13
12
6.8 × 10−5
13
7.0 × 10−16
14
1.7 × 10−4
15
7.0 × 10−19
16
3.6 × 10−7
17
7.0 × 10−22
18
1.2 × 10−8
19
7.0 × 10−25
20
5.0 × 10−10
21
7.0 × 10−28
22
2.0 × 10−11
Table V
Transmittance at 1-Atm Pressure Averaged over 50 cm−1 Intervals