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On the 12 C 2 H 2 near-infrared spectrum: absolute transition frequencies and an improved spectroscopic network at the kHz accuracy level
Lamb dips of twenty lines in the P, Q, and R branches of the ν 1 + ν 3 + ν 4 1 vibrational band of 12 C 2 H 2 , in the spectral window of 7125–7230 cm −1 , have been measured using an upgraded comb-calibrated frequency-stabilized cavity ring-down spectrometer, designed for extensive sub-Doppler meas...
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| Published in: | Physical chemistry chemical physics : PCCP 2023-09, Vol.25 (35), p.23614-23625 |
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| Main Authors: | , , , , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Lamb dips of twenty lines in the P, Q, and R branches of the ν
1
+ ν
3
+ ν
4
1
vibrational band of
12
C
2
H
2
, in the spectral window of 7125–7230 cm
−1
, have been measured using an upgraded comb-calibrated frequency-stabilized cavity ring-down spectrometer, designed for extensive sub-Doppler measurements. Due to the large number of carefully executed Lamb-dip experiments, and to the extrapolation of absolute frequencies to zero pressure in each case, the combined average uncertainty of the measured line-center positions is 15 kHz (5 × 10
−7
cm
−1
) with a 2-σ confidence level. Selection of the twenty lines was based on the theory of spectroscopic networks (SN), ensuring that a large number of transitions, measured previously by precision-spectroscopy investigations, could be connected to the
para
and
ortho
principal components of the SN of
12
C
2
H
2
. The assembled SN contains 331 highly precise transitions, 119 and 121 of which are in the
ortho
and
para
principal components, respectively, while the rest remain in floating components. The
para
- and
ortho
-
12
C
2
H
2
energy-level lists, determined during the present study, contain 82 and 80 entries, respectively, with an accuracy similar to that of the lines. Based on the newly assembled lists of
para
- and
ortho
-
12
C
2
H
2
empirical energy levels, a line list, called TenkHz, has been generated. The TenkHz line list contains 282 entries in the spectral range of 5898.97–7258.87 cm
−1
; thus far, only 149 of them have been measured directly
via
precision spectroscopy. The TenkHz line list includes 35 intense lines that are missing in the HITRAN2020 database. |
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| ISSN: | 1463-9076 1463-9084 |
| DOI: | 10.1039/D3CP01835K |