1. Advertisement

3. PI-12

4. B. V. Perevalov, S. Kassi , and A. Campargue
High sensitivity CW-CRDS spectroscopy of the eight most abundant CO2 isotopologues between 5851 and 7045 cm-1 Critical review of the current databases
B. V. Perevalov, S. Kassi , and A. Campargue
Laboratoire de Spectrométrie Physique, CNRS Université Joseph Fourier de Grenoble, France
V. I. Perevalov , S. A. Tashkun IAO Tomsk, Russia

5. I.- The CW-CRDS spectrometer with DFB lasers in the 1.4-1.7 mm range

6. Cavity Ring Down Sectroscopy
Laser
output T
OFF
time
I output ON
Ring Down !
(1 à 200 µs)
OFF
Laser 

7. Cavity Ring Down T T - empty cell - with gaz t t0 Absorption losses
Laser
output T
Absorption losses
time
Intensity
- empty cell t
- with gaz t0

8. Cavity Ring Down T T Laser output Spectrum Wavelength scan Ring down
variation of the
Ring down

9. PI-08

10. A compact CW-CRDS spectrometer (S. Kassi, D
A compact CW-CRDS spectrometer (S. Kassi, D. Romanini) nm ( cm-1)
6nm/diode
40 diodes
Lambdameter
Laser diode
n=f(T,I)
Optical isolator
Coupler
-50 50
100
threshold
Laser OFF AO
Modulator
laser ON
Photodiode

11. “routine” CW-CRDS (8000) - 7000 - 5850 cm-1 Spectral coverage:
(1250) nm
(8000) cm-1
Typical noise level: amin~3×10-10 cm-1
1 % intensity attenuation after 300 km
High dynamics: absorption coefficients from 10-5 to 10-9 cm-1 are measured on a single spectrum.
Doppler limited resolution
Wavenumber accuracy is about cm-1

12. Illustration of the achieved sensitivity:
The example of the a1Δg(0)−X3Sg(1) of O2
k=8×10-31cm/molec
=2×10-11cm
1 % absorbance after 5000 km
Chem. Phys. Lett. 409 (2005) 281–287

13. the third dimension of an absorption spectrum
Sensitivity:
the third dimension of an absorption spectrum

14. 636
HITRAN

15. 636

16. 636

18. II. Line intensity measurements:

19. 636

20. 636
PI-O6

21. III. Rovibrational analysis
About 10 lines observed/cm-1:
Hot bands up to Elow=3004 cm-1
relative concentration of 5×10-7
Minor isotopologues 828: 3.9×10-6
Impurities (the cell has a good memory!!)

22. Natural isotopic abundance of CO2 molecule
626
636
628
627
638
637
828

23. typical rms values of the residuals ~ 1x10-3 cm-1
band-by-band analysis of 121 and 117 bands for 12C and 13C isotopologues respectively
typical rms values of the residuals ~ 1x10-3 cm-1

24. Effective Hamiltonian Model
S. A. Tashkun, V. I. Perevalov, J. –L. Teffo
1388 cm-1
667 cm-1
2349 cm-1 }
Our spectral region
corresponds to DP= 9
We observe transitions
reaching P=10-13 polyads
with Eup up to 9900 cm-1

25. Excellent agreement with CDSD
However, significant deviations
new fit of the EH parameters
626: JMS 230 (2005) 1–21
636: JMS 226 (2004) 146–160
637 and 638: JMS 241 (2007) 90–100
rms=4.2 ×10-3 cm-1
Intrapolyad interactions are accurately
predicted and reproduced by the EH model
rms=2.7 ×10-3 cm-1

26. Newly evidenced interpolyad anharmonic interaction:
in 638 (2 occurences), 637 (1) and 628 (1)
Example:
638: (P=10) ↔51106 (P= 11)

27. 628
626

28. IV. Comparison with the current CO2 databases

29. 626
bands
lines
4x10-27 28
1903
1x10-26 18
816
4x10-30 50
6210
3x10-29 94
5604
CDSD (4x10-30)
164
13225

30. pure 636 4x10-25 1x10-25 4x10-28 3x10-29 bands lines 8 774 8 259 18
1694
3x10-29
104
4881

31. Line positions
comparison
626
HITRAN-CRDS
GEISA-CRDS
HITEMP-CRDS

32. 626
JPL-CRDS
JPL-CDSD
CDSD-CRDS

33. 628
JPL-CRDS
JPL-CDSD
CDSD-CRDS

34. 636
JPL-CRDS

35. 626
Line intensities comparison

36. pure 636

37. V. Conclusion
The 12CO2 and 13CO2 spectra wer recorded in the 5841–7045 cm-1 region with a typical sensitivity of 3×10-10 cm-1.
The dynamic on the line intensities is from to 3x10-29 cm/molecule.
16932 lines were assigned to 280 bands of 8 isotopologues of CO2.
Our data have allowed a significant improvement of the EHs and EDMs of CDSD

38. Present HITRAN Advantages Drawbacks Complete above 4x10-27
Not sensitive
Deviations<0.02 cm-1

39. Present HITRAN JPL Advantages Drawbacks Complete above 4x10-27
Not sensitive
Deviations<0.02 cm-1
JPL
Very accurate observations for the strongest bands
Pressure shifts and self and air broadening coefficients
Incomplete
Too long range extrapolation (4x10-30)
Some very large deviations
Traceability

40. Present HITRAN JPL CRDS Advantages Drawbacks Complete above 4x10-27
Not sensitive
Deviations<0.02 cm-1
JPL
Very accurate observations for the strongest bands
Pressure shifts and self and air broadening coefficients
Incomplete
Too long range extrapolation (4x10-30)
Some very large deviations
Traceability
CRDS
Nearly complete above 5x10-29
Typical accuracy 1x10-3 cm-1
(1250) nm
(8000) cm-1

41. Present HITRAN JPL CRDS CDSD Advantages Drawbacks
Complete above 4x10-27
Not sensitive
Deviations<0.02 cm-1
JPL
Very accurate observations for the strongest bands
Pressure shifts and self and air broadening coefficients
Incomplete
Too long range extrapolation (4x10-30)
Some very large deviations
Traceability
CRDS
Nearly complete above 5x10-29
Typical accuracy 1x10-3 cm-1
(1250) nm
(8000) cm-1
CDSD
Complete (at least for 626, 636 and 628)
Excellent predictive abilities for positions and intensities
Interpolyad coupling
Cannot reproduce JPL accuracy
A factor of 2 worse than the CRDS accuracy for line centers of the weak bands

42. CH4 (PI-12) N2O 16O3 (III-4), 18O3 (PI-8) C2H2 NO2
Our CW-CRDS spectrometer has allowed similar investigations
for:
H2O, H218O, HDO
CH4 (PI-12)
N2O
16O3 (III-4), 18O3 (PI-8)
C2H2
NO2

43. Merci

44. 12CO2 HITRAN JPL database CRDS Bands Lines 626 28 1903 50(18)
6210(816) 94
5604
628 7
467
15(3)
2713(179) 25
1922
627 3
159 6
1017 11
767
Total 38
2529
71(21)
9940(995)
130
8293

45. 13CO2 HITRAN JPL database This work Bands Lines 636 8 774 18 (8)
1694 (259)
104
4881
638
4 (1)
446 (55) 28
2466
637
2 (0)
184 (0) 11
992
838
0 (0) 4
170
738 3
130
Total
24 (9)
2324 (314)
150
8639