Analysis of high resolution infrared CW-CRDS spectra of ozone in the 6000-6750 cm-1 spectral region A. Barbe, M.R. De Backer-Barilly, Vl.G. Tyuterev, D. Romanini1, S.Kassi1 , A. Campargue1 Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 6089 Université de Reims Champagne – Ardenne France 1 Laboratoire de Spectrométrie Physique, UMR CNRS 5588, Université Joseph Fourier, Saint Martin d’Hères, France

The compact fibered CW-CRDS spectrometer (Grenoble) 1480-1687 nm (5800-7000 cm-1) Typical sensitivity 310-10 cm-1 6nm/diode 40 diodes Laser diode Lambdameter n=f(T,I) Optical isolator Coupler -50 50 100 threshold Laser OFF AO Modulator laser ON Photodiode

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

Intensity calculations

Region ( 233-000 ) 6720 cm-1 Observed absorption coefficient (10-6 cm-1)

E/hc (cm-1) (412) 6800 (242) (520) (171) (233) 6700 (313) (350) 6600 Ka = 6 Ka = 5 Ka = 10, 11 Ka = 9, 10 Ka = 12 Ka = 11 Ka = 7,8,9 Ka = 6,7,8 Ka = 5,6,7 Ka = 4,5,6 Ka = 3 E/hc (cm-1) Ka = 0,1,2 (313)

% on (520) in (233)

% on (520) in (242)

Spectroscopic parameters (cm-1) (350) (233) (171) (520) (242) (412) EVV 6671.203 (10) 6716.536163 (80) 6728.683 (f) 6751.2465 (21) 6764.45674 (29) 6820.252 (11) A-(B+C)/2 3.230068 (85) 3.1243593 (67) 3.37 (f) 3.185396 (22) 3.200539 (14) 2.811073 (38) (B+C)/2 0.398264 (14) 0.38917245 (70) 0.3948 (f) 0.4068265 (54) 0.3929780 (11) 0.393939 (21) (B-C)/2 0.024001 (30) 0.02663268 (95) 0.0227 (f) 0.0209819 (11) 0.02688310 (79) 0.025125 (f) DK 103 g 0.33969 (13) 0.2153 (14) 0.14547 (22) DJK 105 0.20139 (53) -0.8612 (23) DJ 106 0.50785 (39) 1.4459 (33) 0.2514 (10) dJ 0.10107 (28) 0.13684 (28) dK 0.7052 (42) 1.0078 (64) HK 0.24415 (69) HKJ 107 0.4820 (19) Coupling parameters

Statistics for rovibrational transition calculation (233)(010) (233)(000) (242)(000) (520)(000) Band center (cm-1) 6015.605 6716.536 6764.456 6751.246 J max 37 46 33 Ka max 9 12 7 Number of transitions 322 797 r.m.s. (103) (cm-1) 3.7 8.5 7.5

Transition moment operator parameters (Debye) Value Number of transitions (J max, Ka max) rms deviation (%) 2n1 + 3n2 +3n3 band d1 (×104) 0.29188 (35) 213 (36, 13) 16.7 % d2 (×108) - 0 .3552 (23) d3 (×107) 0.1689 (28) d6 (×107) - 0.582 (16) d7 (×107) - 0.554 (16) 2n1 + 4n2 + 2n3 band d1 (×105) 0.3112 (25) 102 (42, 9) 24.0 % d5 (×106) - 0.46620 (49) 2n1 + 3n2 +3n3 – n2 band d1 (×103) 0.12579 (23) 104 (33, 9) 23.4 % d2 (×107) - 0.7561 (28) d4 (×106) - 0.2938 (10)

Statistics for line intensities 2n1 + 3n2 +3n3 band 2n1 + 4n2 + 2n3 band 2n1 + 3n2 +3n3 – n2 band Deviation Number of lines 158 (74.2 %) 79 (77.4 %) 74 (71.2 %) 40 (18.8 %) 18 (17.6 %) 26 (25 %) 15 (7 %) 5 (5 %) 4 (3.8 %) rms = 16.7 % rms = 24.0 % rms = 21.1 %

Final comparison between Observed and Calculated spectrum

Comparison between Obs. and Calc. spectrum in the P branch of 21+32+33 (J’= 14) 141 142 143 144 145 360 371 Observed spectrum Calculated spectrum CO2 H2O

E (cm-1) Nb DE O-C vib J Ka Kc 6717.3035 1 -10.8 233 6721.1925 -8.8 3 6728.1757 2 1.4 -7.6 5 6738.2282 0.2 7 6751.3204 0.3 -4.3 9 6767.4100 5.8 11 6786.4474 0.5 -2.6 13 6808.4097 4 1.5 15 6833.2633 0.6 17 6860.9959 1.1 19 6891.6000 0.8 21 6925.0791 1.0 2.5 23 6961.4286 1.8 -3.3 25 7000.6349 3.8 -3.0 27 7042.7524 0.7 -1.2 29 7087.7359 1.6 -5.5 31 7135.6120 2.7 33 7186.3675 9.7 35 6720.4562 -8.9 6721.9063 -8.0 6724.4815 -7.4 6727.1665 2.9 -5.4 6731.7199 -7.7

Global survey of the 6000 – 6200 cm-1 spectral range 2n1+2n2+3n3 # n1+2n2+4n3 n1+5n3 # 2n1+3n2+3n3-n2 3n2+4n3 5n1+n2 Global survey of the 6000 – 6200 cm-1 spectral range 7 different diodes : without impurities : CO2, H2O, CO

Observing and assigning B type bands (ΔKa= ± 1) in this high level range represents an challenge. With previous work done with the F.T.S, the highest observed bands were 2n1+2n3( 4141 cm-1) and 2n1+n2+2n3 (4783 cm-1). In general , FOR OZONE, this type of band is much more difficult to assign than A type bands, were strong compressed R branch appear, for several reasons: They are much weaker than A type bands at a given energy level range. They extend over a much larger spectral range, and , as a consequence, are never totally observed , being overlapped by stronger A type bands, and often partly hidden by impurities, like H2O,CO2,CO… The general shapes of theses bands are difficult to reproduce in a first attempt, as 6 type of transitions may be observed, and the introduction of unknown additional transition moment parameters is obligatory to reproduce line intensity observations.( as example μ 5 terms must be introduce to “ reduce” Q branches which are not visible in our spectra ).

Calculated spectra of 1+22+43 in 3 cases (normalisation on observed lines in the 6155 cm-1 region) All  of A and B bands All  of B band; A =0 Only 1 for B band ( 5=0):

Observed and calculated spectrum of the n1 + 2n2 +4n3 band in the 6156 – 6157 cm-1 range * Observed Calculated CO2 301 312 235 226 266 257 212 221 232 241 291 280 252 261 192 201 Wavenumber (cm-1) Absorption Coefficient (a.u.)

(331-000) the weakest band observed so far 310-28 cm-1 molecule cm-2 Observed spectrum Calculated (331)-(000) Calculated (124)-(000) CO2

Vibrational Assignment Assigned transitions in the range 6000—6900cm-1 Nature of the work Vibrational Assignment Band center Number of transitions J max Ka max completed 233-010 6015.605 350 37 11 034-000 6046.970 138 40 4 105-000 6063.933 531 43 10 510-000 * 6100.216 122 29 223-000 6124.286 520 44 14 124-000* 6154.702 498 49 7 331-000 6198.534 116 23 6 In progress 025-000 6305.039 992 39 12 501-000 6355.739 593 6386.981 548 36 421-000 6568.079 65 27 2 205-000 6586.969 398 233-000 6716.536 483 520-000 * 6751.246 22 33 242-000 * 6764.456; 399 46 9 007-000 6895.493 284 TOTAL : 5959

Observed – Predicted (cm-1)Range 4250-5520 Vibrational state Observed – Predicted (cm-1)Range 4250-5520 202 +0.021 301 +0.0280 023 +0.288 122 -0.030 221 +0.035 014 +0.292 320 -0.131 113 +0.279 212 +0.139 311 +0.433 005 +0.411 104 +0.584 203 -0.090 302 +0.656 123 -0.094 401 +0.050 015 +0.136 Vibrational state Observed – Predicted # (cm-1)Range 5540-6780 114 +0.558 015 -0.396 105 0.896 232 -1.526 105/303 +0.320 510 +0.808 223 -1.748 124 -0.397 331 +0.712 025 -2.192 501 +0.243 223/313 +0.428 421 -0.227 205 -0.566 233/143 5.162 520 -1.902 242 2.757 Vl.G. Tyuterev, H. Seghir, A. Barbe, S.A. Tashkun, « Ozone molecule : high energy resonances, consistency of variational and perturbative calculations and complete vibration assignments up to dissociation », HRMS, Praha 2006

Conclusion This work , thanks to the high sensitivity of the experimental set-up (CW-CRDS) allows to observe many weak rovibrational transitions of ozone. All the « relatively strong or of medium intensity « are rotationally undoubtedly assigned. It confirms previous work done with FTS, that is to say, that above 3300 cm-1,the simplified scheme of ozone, including poylads corresponding to the same value of v2, with Darling-Dennison resonances between v1,v2,v3 and v1±2,v2,v3 Ŧ 2 states and coriolis resonances between v1,v2,v3and v1 Ŧ 1,v2,v3 ± 1 states is no more valid : large vibrational couplings arise between all states in a neighborhood, even with large value of v2. As a result, predictions of the strengths of interactions between various partners become a real challenge, as the number of possibly interacting states become obviously larger and larger as far as energy is increasing. Remember that highest observations are near 7000 cm-1, the dissociation limit being near 8600 cm-1. Prediction of rotational constants also is difficult. Nevertheless, we have been able, in two spectral regions, to complete the works, that is to say find suitable models, for positions and intensities which reproduce correctly ( near the experimental accuracy) the observed spectra. Consequently, we give for these works not only hamiltonian parameters and transition moment parameters, but also energy levels, corresponding to observed transitions. It has also been possible to reproduce B type bands, despite the difficulties mentioned during this talk. A s final conclusion, we will continue to advance theoretically and experimentally, simultaneously, to have a final good understanding of the dipole and potential function of ozone