Transition Moment Operator Research Articles

Line intensities for the ν6 and 2ν3 bands of methyl iodide (12CH3I)

The goal of this study is to measure for the first time absolute line intensities for the ν6 band of methyl iodide (CH3I) centered at 892.918 cm–1. High-resolution Fourier transform spectra were recorded at various pressures for the whole 500–1450 cm–1 spectral range. Using these spectra, a large set of CH3I individual line intensities was measured for the ν6 band. These experimental intensities were least squares fitted to derive the expansion of the ν6 transition moment operator. The theoretical model used to describe the line positions and intensities accounts for the hyperfine structure in the 61 and ground states and for the vibration-rotation resonances that couple the 61 energy levels with those of the 32 and 21 vibrational states [Perrin et al., J. Mol. Spectrosc. 324 (2016) 28–35]. As the 2ν3 band is extremely weak, its associated transition moment operator was estimated from band strength available in the literature. A comprehensive list of line positions and intensities was generated for the ν6 and 2ν3 bands of CH3I at 11 µm, which should be useful for the possible detection of this species by the future IASI-NG satellite instrument (Infrared Atmospheric Sounding Interferometer New Generation), now under preparation (https://iasi-ng.cnes.fr/en/IASI-NG/index.htm).

Three new bands of 18O16O18O by CW-CRDS between 6340 and 6800 cm−1

Three very weak bands of the 18O16O18O isotopologue of ozone have been detected by high sensitivity CW-Cavity Ring Down Spectroscopy between 6340 and 6800cm−1. They are vibrationally assigned as 2ν1+5ν3, ν1+4ν2+3ν3 and 3ν2+5ν3 and correspond to the highest frequency bands of this isotopologue detected so far. A total of 464, 318 and 194 transitions were rovibrationally assigned, respectively. The good agreement with theoretical values achieved for the derived band centres and rotational constants confirms the accuracy of the potential energy surface recently obtained via extensive ab initio calculations. A set of line intensities was measured and fitted to derive the first transition moment parameter of the three bands. The determined sets of effective Hamiltonian parameter and transition moment operators, as well as the experimental energy levels, were used to generate a complete list of 1526 transitions, provided as Supplementary materials. The calculated line-list allows generating a synthetic spectrum which reproduces satisfactorily the experimental spectrum.

New line positions analysis of the ν1+ν2+ν3 band of NO2 at 3637.848 cm−1

Using high resolution Fourier transform spectra, a new investigation of the ν1+ν2+ν3 absorption band of nitrogen dioxide, 14N16O2, located at 3637.8479(3)cm−1 was performed. The assigned ν1+ν2+ν3 lines involve energy levels of the (1,1,1) vibrational state with rotational quantum numbers up to Ka=12 and N=54. The energy levels were satisfactorily reproduced within their experimental uncertainty using a theoretical model which takes explicitly into account the Coriolis interactions coupling the (1,1,1) levels with those of the (1,3,0) and (2,1,0) dark states, together with the spin–rotation interactions within (1,1,1) and (1,3,0) and (2,1,0). As a consequence, precise vibrational energies, rotational, spin–rotational and coupling constants were achieved for the triad {(2,1,0),(1,3,0),(1,1,1)} of interacting states of 14N16O2. Using these parameters together with the transition moment operator of the ν1+ν3 band achieved during previous studies [Mandin JY, Dana V, Perrin A, Flaud JM, Camy-Peyret C, Régalia L, Barbe A, J Mol Spectrosc 1997;181: 379–388], we have generated an improved set of line parameters (line positions and line intensities) for the ν1+ν2+ν3−ν2 hot band of 14N16O2 which absorbs together with the ν1+ν3 cold band in the 3.4µm region.

Detection and analysis of four new bands in CRDS 16O3 spectra between 7300 and 7600 cm−1

The absorption spectrum of the 16O3 isotopologue of ozone was recorded in the 7000–7920cm−1 region by using high sensitivity CW-Cavity Ring Down Spectroscopy (αmin∼10−10cm−1). This report is devoted to the analysis of the 7300–7600cm−1 region dominated by four A-type bands: 6ν1+ν3 centred around 7395cm−1, 3ν1+5ν2+ν3 and 2ν1+4ν2+3ν3 lying in the 7450cm−1 region and 5ν1+2ν2+ν3 centred around 7579cm−1. 213 transitions of the 6ν1+ν3 band were assigned and the corresponding line positions were modeled using an effective Hamiltonian including a Coriolis resonance interaction between the (601) upper state and a A-type dark state. The two very close 3ν1+5ν2+ν3 and 2ν1+4ν2+3ν3 bands were analysed using a similar effective Hamiltonian scheme involving the anharmonic resonance coupling between the (351) and (243) states. For these two bands, 304 transitions were assigned. The modelling also includes a first Coriolis resonance interaction between the (351) bright state and the (530) dark state, and a second one between the (243) bright state and the (144) dark state. In the 7579cm−1 region, 205 transitions of the 5ν1+2ν2+ν3 band were assigned and modelled taking into account the Coriolis resonance interactions between the (521) upper state and the (700), (342) and (280) dark states.The dipole transition moment parameters of the four analysed bands were determined by a least-squares fit to the measured line intensities. For the studied band systems, the effective Hamiltonian and transition moment operator parameters were used to generate line lists provided as Supplementary Materials.

Detection and analysis of new bands of 16O 3 by CRDS between 6500 and 7300 cm −1

The absorption spectrum of the 16O 3 isotopologue of ozone has been recorded in the 7000–7920 cm −1 region by high sensitivity CW-Cavity Ring Down Spectroscopy. This report is devoted to the analyses of the 7065–7300 cm −1 region dominated by the ν 1 + 2 ν 2 + 5 ν 3 and ν 1 + 5 ν 2 + 3 ν 3 A-type bands at 7130.8 and 7286.8 cm −1 respectively. 289 transitions were assigned to the ν 1 + 2 ν 2 + 5 ν 3 band. The corresponding line positions were modeled with an effective Hamiltonian involving Coriolis resonance interactions between the (1 2 5) upper state and the (4 4 0), (0 2 6) and (6 1 0) dark states, and an anharmonic resonance interaction with the (2 0 5) state. The very strong interaction (up to 50% mixing of the wavefunctions) between the (1 2 5) and (6 1 0) states leads to the observation of two extra lines of the 6 ν 1 + ν 2 band due to a resonance intensity transfer. 213 transitions of the ν 1 + 5 ν 2 + 3 ν 3 band were assigned and modeled taking into account a Coriolis resonance interaction with the (3 6 0) state. We take the opportunity of the present work to report the analysis of the very weak 4 ν 2 + 4 ν 3 B-type band at 6506.1 cm −1 which was assigned from previously recorded CRDS spectra. 286 transitions were modeled using the effective Hamiltonian approach. The dipole transition moment parameters of the three analyzed bands were determined by a least-squares fit to the measured line intensities. For the three studied band systems, the effective Hamiltonian and transition moment operator parameters were used to generate line lists provided as Supplementary Materials.

CW-Cavity Ring Down spectroscopy of 18O 3. Part 1: Experiment and analysis of the 6200–6400 cm −1 spectral region

The absorption spectrum of the 18O 3 isotopologue of ozone has been recorded in the 6200–6400 cm −1 region by high sensitivity CW-Cavity Ring Down Spectroscopy. The spectrum is dominated by the 2ν 1 + 5ν 3 and 2ν 1 + 3ν 2 + 3ν 3 bands at 6270.6 and 6392.2 cm −1, respectively which were treated independently. The rovibrational analysis of the 2ν 1 + 5ν 3 band has evidenced that the (2 0 5) upper state is perturbed by Coriolis resonance interactions with the (0 1 6), (3 0 4) and (3 5 0) states. A total of 659, 89, 131 and 5 transitions were assigned to the 2ν 1 + 5ν 3, ν 2 + 6ν 3, 3ν 1 + 4ν 3 and 3ν 1 + 5ν 2 bands, respectively. In the case of the 2ν 1 + 3ν 2 + 3ν 3 band, 344 transitions were assigned. Some of them were found perturbed by a Coriolis interaction of the (2 3 3) state with the (5 2 0) state. Overall, 681 energy levels were derived from the analysis of the 2ν 1 + 5ν 3 and 2ν 1 + 3ν 2 + 3ν 3 band systems. In both cases, a suitable effective Hamiltonian was elaborated, allowing accounting satisfactorily for the retrieved rovibrational energy levels. In addition, dipole transition moment parameters were determined by a least-squares fit to the measured line intensities. The effective Hamiltonian and transition moment operator parameters were used to generate a list of 1619 transitions given as Supplementary material.

Line intensities for the ν1, ν3 and ν1+ ν3 bands of 34SO 2

Using both high resolution (0.0018 cm −1) and medium resolution (0.112 cm −1) Fourier transform spectra of an enriched 34S (95.3%) sample of sulfur dioxide, it has been possible to accurately measure a large number of individual line intensities for some of the strongest of the SO 2 bands, i.e. ν 1, ν 3 and ν 1+ ν 3. These intensities were least-squares fitted using a theoretical model which takes into account the vibration–rotation interactions linking the upper energy levels where needed, and, in this way, expansions of the various transition moment operators were determined. The Hamiltonian parameters determined in previous analyses together with these moments were then used to generate synthetic spectra for the bands studied and their corresponding hot bands providing one with an extensive picture of the absorption spectrum of 34SO 2 in the spectral domains, 8.7, 7.4, and 4 μm.

Tensorial development of the rovibronic Hamiltonian and dipole moment operators for XY 3Z molecules with a degenerate electronic state: Preliminary application to the CH 3O radical

We present a development of the Hamiltonian and transition moment operators of XY 3Z ( C 3 v ) symmetric tops molecules in a degenerate electronic state with the aid of a tensorial formalism developed in a recent paper [A. El Hilali, V. Boudon, M. Loëte, J. Mol. Spectrosc. 239 (2006) 41–50]. Electronic operators are defined from group theory properties. They provide a new approach to build an effective rovibronic Hamiltonian as well as an effective dipole moment operator for rovibronic transition of XY 3Z molecules. This model is studied qualitatively thanks to the tensorial algebra properties. Expressions of the matrix elements are derived for these operators. A first simple application to the ground electronic state of CH 3O is proposed as an illustrative example.

The near infrared spectrum of ozone by CW-cavity ring down spectroscopy between 5850 and 7000 cm−1: new observations and exhaustive review

Weak vibrational bands of (16)O(3) could be detected in the 5850-7030 cm(-1) spectral region by CW-cavity ring down spectroscopy using a set of fibered DFB diode lasers. As a result of the high sensitivity (noise equivalent absorption alpha(min) approximately 3 x 10(-10) cm(-1)), bands reaching a total of 16 upper vibrational states have been previously reported in selected spectral regions. In the present report, the analysis of the whole investigated region is completed by new recordings in three spectral regions which have allowed: (i) a refined analysis of the nu(1) + 3nu(2) + 3nu(3) band from new spectra in the 5850-5900 cm(-1) region; (ii) an important extension of the assignments of the 2nu(1)+5nu(3) and 4nu(1) + 2nu(2) + nu(3) bands in the 6500-6600 cm(-1) region, previously recorded by frequency modulation diode laser spectroscopy. The rovibrational assignments of the weak 4nu(1) + 2nu(2) + nu(3) band were fully confirmed by the new observation of the 4nu(1) + 2nu(2) + nu(3)- nu(2) hot band near 5866.9 cm(-1) reaching the same upper state; (iii) the observation and modelling of three A-type bands at 6895.51, 6981.87 and 6990.07 cm(-1) corresponding to the highest excited vibrational bands of ozone detected so far at high resolution. The upper vibrational states were assigned by comparison of their energy values with calculated values obtained from the ground state potential energy surface of (16)O(3). The vibrational mixing and consequently the ambiguities in the vibrational labelling are discussed. For each band or set of interacting bands, the spectroscopic parameters were determined from a fit of the corresponding line positions in the frame of the effective Hamiltonian (EH) model. A set of selected absolute line intensities was measured and used to derive the parameters of the effective transition moment operator. The exhaustive review of the previous observations gathered with the present results is presented and discussed. It leads to a total number of 3863 energy levels belonging to 21 vibrational states and corresponding to 7315 transitions. In the considered spectral region corresponding to up to 82% of the dissociation energy, the increasing importance of the "dark" states is illustrated by the occurrence of frequent rovibrational perturbations and the observation of many weak lines still unassigned.

The ν1 + 3 ν2 + 3 ν3 and 4 ν1 + ν2 + ν3 bands of ozone by CW-cavity ring down spectroscopy between 5900 and 5960 cm −1

The absorption spectrum of ozone, 16O 3, has been recorded in the 5903–5960 cm −1 region by high sensitivity CW-cavity ring down spectroscopy ( α min ∼ 5 × 10 −10 cm −1). The ν 1 + 3 ν 2 + 3 ν 3 and 4 ν 1 + ν 2 + ν 3 A-type bands centred at 5919.15 and 5947.07 cm −1 were newly observed. A set of 173 and 168 energy levels could be experimentally determined for the (1 3 3) and (4 1 1) states, respectively. Except for a few K a = 5 levels of the (4 1 1) state, the rotational structure of the two states was found mostly unperturbed. The spectroscopic parameters were determined from a fit of the corresponding line positions by considering the (1 3 3) and (4 1 1) states as isolated. The determined effective Hamiltonian and transition moment operators were used to generate a list of 785 transitions given as Supplementary Material.

CW-Cavity Ring Down Spectroscopy of the ozone molecule in the 5980–6220 cm −1 region

The absorption spectrum of ozone, 16O 3, has been recorded in the 5980–6220 cm −1 region by high sensitivity CW-Cavity Ring Down Spectroscopy ( α min ∼ 3 × 10 −10 cm −1). This study extends a first investigation with the same experimental set-up limited to the 6030–6090 cm −1 spectral region [M.-R. De Backer-Barilly, A. Barbe, Vl.G. Tyuterev, D. Romanini, B. Moeskops, A. Campargue, J. Mol. Struct. 780–781 (2006) 225–233] where the analysis of two A-type bands was reported, using FTS spectra for complementary information. The spectral extension of the recordings allows not only to enlarge considerably the observed transitions of these two bands, but more importantly, to assign four new bands: the 3 ν 2 + 4 ν 3,5 ν 1 + ν 2 and ν 1 + 2 ν 2 + 4 ν 3 B-type bands which were considered as dark in our previous report and the 3 ν 1 + 3 ν 2 + ν 3 A-type band. The high mixing of the observed states approaching the dissociation limit, leads to the breakdown of the polyad structure and ambiguities in the vibrational labelling which are discussed. Finally, 1789 transitions were assigned, and a suitable Hamiltonian model allows reproducing correctly the observations for five of the six observed bands. The list of 1004 experimentally determined energy levels is provided. The determined effective Hamiltonian and transition moment operators were used to generate a list of 5338 transitions given as Supplementary Material. It is interesting to note that the d 5 parameter of the effective transition moment is of great importance to account for the observed intensities of the B-type bands.

New high-resolution analysis of the { ν1 + ν3} band of the 15N 16O 2 isotopomer of nitrogen dioxide: Line positions and intensities

The high-resolution Fourier transform absorption spectrum of an isotopic sample of nitrogen dioxide, 15N 16O 2, was recorded in the 3.4 μm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242 (1991) 367–377] a new analysis of the ν 1 + ν 3 band located at 2858.7077 cm −1 has been performed. This new assignment concerns (1 0 1) energy levels involving rotational quantum numbers up to K a = 10 and N = 54. Using a theoretical model which accounts for both the electron spin-rotation resonances within each vibrational state and the Coriolis interactions between the (1 2 0) and (1 0 1) vibrational states, the spin-rotation energy levels of the (1 0 1) vibrational state could be reproduced within their experimental uncertainty. In this way, the precise vibrational energy, rotational, spin-rotation, and coupling constants were achieved for the {(1 2 0), (1 0 1)} interacting states of 15N 16O 2. Using these parameters and the transition moment operator which was obtained for the main isotopic species, 14N 16O 2, a comprehensive list of the line positions and intensities was generated for the ν 1 + ν 3 band of 15N 16O 2.

CW-cavity ring down spectroscopy of the ozone molecule in the 6625–6830 cm −1 region

The absorption spectrum of ozone, 16O 3, has been recorded by CW-cavity ring down spectroscopy in the 6625–6830 cm −1 region. The typical sensitivity of these recordings ( α min ∼ 3 × 10 −10 cm −1) allows observing very weak transitions with intensity down to 2 × 10 −28 cm/molecule. 483 and 299 transitions have been assigned to the 2 ν 1 + 3 ν 2 + 3 ν 3 A-type band and to the 2 ν 1 + 4 ν 2 + 2 ν 3 B-type band, respectively, which are the highest frequency bands of ozone recorded so far under high resolution. Rovibrational transitions with J and K a values up to 46 and 12, respectively, could be assigned. Despite well-known difficulties to correctly reproduce the energy levels not far from the dissociation limit, it was possible to determine the parameters of an effective Hamiltonian which includes six vibrational states, four of them being dark states. The line positions analysis led to an rms deviation of 8.5 × 10 −3 cm −1 while the experimental line intensities could be satisfactorily reproduced. Additional experiments in the 5970–6021 cm −1 region allows detecting the (233) ← (010) hot band reaching the same upper state as the preceding cold band. From the effective parameters of the (233) state just determined and those of the (010) level available in the literature, 329 transitions could be assigned and used for a further refinement of the rovibrational parameters of the effective Hamiltonian leading to a value of 7.6 × 10 −3 cm −1 for the global rms deviation. The complete list of the experimentally determined rovibrational energy levels of the (233), (242), and (520) states is given. The determined effective Hamiltonian and transition moment operators allowed calculating a line list (intensity cut off of 10 −28 cm/molecule at 296 K), available as Supplementary material for the 6590–6860 and 5916–6021 cm −1 regions. The integrated band strength values are 1.75 × 10 −24 and 4.78 × 10 −25 cm/molecule at 296 K for the 2 ν 1 + 3 ν 2 + 3 ν 3 A-type band and to the 2 ν 1 + 4 ν 2 + 2 ν 3 B-type band, respectively, while the band intensity value of the (233) ← (010) is estimated to be 1.03 × 10 −24 cm/molecule.

The ν5 and 2 ν9 bands of the 15N isotopic species of nitric acid (H 15NO 3): Line positions and intensities

Nitric acid (HNO 3) plays an important role in the Earth’s atmosphere as a reservoir molecule of NO x species. It has a strong infrared signature at 11 μm which is one of the most commonly used for the infrared retrieval of this species in the atmosphere since this spectral region coincides with an atmospheric window. It is therefore essential to have high quality spectral parameters in this spectral region. For the H 14NO 3 (main) isotopic species, the 11 μm bands were already the subject of numerous extensive studies which involve not only the ν 5 and 2 ν 9 cold bands but also the first hot bands. The present work is the first high resolution Fourier transform analysis of the 11 μm bands for H 15NO 3, which is the second most abundant isotopomer of nitric acid [ a ≅ 0.00365(7)]. In this way, the analysis of the ν 5 and 2 ν 9 cold bands centered at 871.0955 and 893.4518 cm −1 was performed, and as for H 14NO 3, these bands are significantly perturbed since rather strong resonances couple the 5 1 and 9 2 rotational levels. The theoretical model that we used to compute the line positions and line intensities is directly issued from the one which we used recently for H 14NO 3 [A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mäder, D. Walbrodt, M. Winnewisser, J. Mol. Spectrosc. 228 (2004) 375–391]. Actually, for the H 15NO 3 line positions, the Hamiltonian matrix accounts for the rather strong Fermi and the weaker Coriolis interactions linking the 5 1 ⇔ 9 2 rotational levels. Using this model which accounts correctly for the strong mixing of the 5 1 and 9 2 upper state energy levels, the ν 5 and 2 ν 9 line intensities for H 15NO 3 were satisfactorily computed using the ν 5 and 2 ν 9 transition moment operators achieved previously for the 14N (main) isotopic species. In this way, the transfer of intensities from the ν 5 fundamental (and presumably strong) band to the 2 ν 9 overtone (and presumably weak) band could be explained for H 15NO 3 as it was done previously for the 14N (main) isotopic species. Finally, the position of the H 15NO 3 ν 5 + ν 9 − ν 9 hot band was identified at 875.245 cm −1.

Development of the Hamiltonian and transition moment operators of symmetric top molecules using the O (3) ⊃ C∞ v ⊃ C3 v group chain

We present a development of the Hamiltonian, dipole moment, and polarizability operators for XY 3Z molecules. These rovibrational operators are written with the aid of a tensorial formalism derived from the one already used in Dijon and adapted to the XY 3Z symmetric tops in a recent paper [A. El Hilali, V. Boudon, M. Loëte, J. Mol. Spectrosc. 234 (2005) 166–174]. We use the O (3) ⊃ C ∞ v ⊃ C 3 v group chain. Expressions for the matrix elements are derived for these operators.

Fourier transform and high sensitivity cw-cavity ringdown absorption spectroscopies of ozone in the 6030–6130 cm −1 region. First observation and analysis of the 3 ν1+3 ν3 and 2 ν2+5 ν3 bands

The absorption spectrum of 16O 3 has been recorded between 6030 and 6130 cm −1 by Fourier Transform Spectroscopy (GSMA, Reims) and cw-cavity ringdown spectroscopy (LSP, Grenoble). The two new bands 3 ν 1+3 ν 3 and 2 ν 2+5 ν 3 centered at 6063.923 and 6124.304 cm −1, respectively are observed and analyzed. Rovibrational transitions with J and K a values up to 40 and 10, respectively, could be assigned. The rovibrational fitting of the observed energy levels shows that some rotational levels of the (303) and (025) bright states are perturbed by interaction with the (232), (510) and (124) dark states. The observed energy levels could be reproduced with a rms deviation of 5×10 −3 cm −1 using a global analysis based on an effective Hamiltonian including the five interacting states. The energy values of the three dark vibrational states provided by the fit are found in good agreement with theoretical predictions. The parameters of the resulting effective Hamiltonian and of the transition moment operator retrieved from the measured absolute line intensities allowed calculating a complete line list of 2035 transitions, available as Supplementary Material. The integrated band strengths are estimated to be 1.22×10 −24 and 3.15×10 −24 cm −1/(mol cm −2) at 296 K for the 3 ν 1+3 ν 3 and 2 ν 2+5 ν 3 bands, respectively. A realistic error for these band strengths is 15% (see text).

First high-resolution analyses of the ν8 and ν8 + ν9 spectral regions of 35CIONO2: determination of the ν9 band centre

A ro-vibrational analysis of the C-type ν8 fundamental band of 35CIONO2 as well as the hot band ν8 + ν9 − ν9 has been carried out using a Fourier-transform infrared spectrum of natural chlorine nitrate recorded with a resolution of 0.000 94cm−1 at a temperature of 190 K. Accurate upper state constants have been determined for both bands including the following band centres: ν0 (ν8) = 711.207 63(9) and ν0(ν8 + ν9 − ν9) = 714.905 0(12)cm−1. These constants have been used, together with a transition moment operator that takes into account the observed Herman-Wallis effect, to successfully model the experimental spectrum. In addition, the constants of the 8191 state have been used to model the ν8 + ν9 band, allowing us to assign nearly 100 Q-branch transitions and, therefore, to determine the band centre of the ν8 + ν9 band, ν0(ν8 + ν9) = 838.626 9(15)cm−1 Consequently this allows us to obtain the band centre of ν9: ν0(ν9) = 123.721 9(20)cm−1. This establishes unambiguously that the band at 714.9cm−1 previously attributed to ν5 + ν7 − ν9 is actually the ν8 + ν9 − ν9 hot band.

Spectroscopy of X2Y4 ( D2 h) molecules: tensorial formalism adapted to the O(3)⊃ D2 h chain, Hamiltonian and transition moment operators

A tensorial formalism adapted to the case of the X 2 Y 4 molecules with D 2 h symmetry has been developed in the same way as in the previous works on XY 4 ( T d ) and XY 6 ( O h ) spherical tops and XY 5 Z ( C 4 v ) symmetric tops. Here, we use the O(3)⊃ D 2 h group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain and used in the case of the Hamiltonian and transition moment operators.

Tensorial development of the rovibronic Hamiltonian and transition moment operators for octahedral molecules

We present a development of the Hamiltonian, dipole moment and polarizability operators of octahedral XY6 molecules in a degenerate electronic state. These rovibronic operators are written with the aid of a tensorial formalism derived from the one already used in Dijon in the case of molecules in a non-degenerate electronic state. Electronic operators are defined from the group theory properties. Transition moment operators are introduced in order to consider rovibronic transitions. Spectrum simulations are made thanks to a new version of the HTDS sofware [J. Quant. Spectrosc. Radiat. Transfer 66 (2000) 16] used for the calculation of rovibrational spectra.

Absolute Intensities of the ν1 and ν3 Bands of 16O3

New experimental data on the ν1 and ν3 bands of 16O3 improving the value of absolute line intensities have been obtained. The intensities of 295 lines have been measured with an average accuracy between 2.5% and 3% and the rotational expansion of the transition moment operators for the ν1 and ν3 bands has been deduced. Finally, a complete listing of line intensities has been computed with an intensity cutoff of 1×10−25 cm−1/molecule cm−2.