Search

We report the spectrum of the ν1 fundamental of chlorine dioxide centered in the infrared atmospheric window at 945.592 cm-1 measured with essentially Doppler limited resolution at an instrumental line width of 0.001 cm-1 using the Zurich prototype ZP2001 Bruker IFS 125 HR Fourier transform infrared spectrometer. The ro-vibrational line analysis is carried out with an improved effective Hamiltonian and a newly developed computer code ROVDES for the ro-vibrational spectra of open-shell free radical molecules including spin-rotation interactions. Accurate values of rotational, centrifugal and spin-rotational parameters were determined for 16O35Cl16O in the vibronic ground state X2B1 from more than 3500 ground state combination differences. The 7239 assigned transitions for the ν1 fundamental with Nmax = 76 and Kmaxa = 26 provide a set of 32 accurate effective Hamiltonian parameters for the ν1 fundamental (v1v2v3) = (100) (21 rotational and centrifugal distortion parameters and 11 spin-rotational interaction parameters). This effective Hamiltonian (A - reduction and Ir - representation) reproduces 1703 upper state energies from the experiment with a root-mean-square deviation drms = 1.67 × 10-4 cm-1 and the 7239 transition wavenumbers with drms = 3.45 × 10-4 cm-1. Our results provide a considerable improvement over previous results with which we compare and should provide a benchmark for theoretical studies with applications to atmospheric spectroscopy and laser chemistry, which are discussed in relation to our spectra.

The high–resolution infrared spectrum of C2H2D2-cis was recorded for the first time and analyzed in the region of 2400–2700 cm − 1 , where the ν 2 + ν 6 band is located. 1987 transitions were assigned to the ν 2 + ν 6 band and 623 ro–vibrational energies of the ( v 2 = v 6 = 1 ) vibrational state were determined from the assigned transitions. Parameters of the effective Hamiltonian were determined from the weighted fit, which takes into account the studied ( v 2 = v 6 = 1 ) vibrational state and six other closely located (but experimentally here not visible) vibrational states of C2H2D2-cis. The obtained “experimental” energy values were used as initial information in the fit. Determined from the fit, a set of 95 parameters reproduces 623 initial energy values of the ( v 2 = v 6 = 1 ) vibrational state, representing 1987 line positions of the ν 2 + ν 6 band with the d rms = 3.98 × 10 − 3 cm − 1 .

The high-resolution infrared spectra of 12C2H4 were analyzed in the region of 1360 – 1530 cm − 1 , where the strong ν12 band is located. 998 line strengths (1491 transitions) were determined from the fit of their line shapes with a Hartmann–Tran profile ( J max = 48 and K a max = 17 ) which is about two times more than in the preceding studies. These data were used in the fit of the effective dipole moment parameters and six such parameters were obtained which reproduce the strengths of the 998 initial lines (1491 transitions) with the d rms = 2.31 % . Self–broadening and self-shift coefficients were determined from the multi–spectrum analysis for sets of lines ( J K a = K a ′ K c ) ← ( J ′ K a ′ K c ′ ) , K a ′ = 0 , 1 , 2 , 3 , 4 , 5 (in general, 253 lines for determination of self-broadening coefficients and 225 lines for determination of self-shift coefficients). The line list of 19186 transitions is documented.

The high–resolution infrared spectrum of the HDS isotopologue was recorded and analyzed in the region of the ν2 fundamental band region (700–1400 cm − 1 ) with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zurich prototype ZP2001). Among the lines of the ν2 band of the HD32S and HD34S molecules, 801 transitions of HD33S were found in the spectrum and assigned for the first time (Jmax = 19 and K a max = 12). Also for the first time, rotational energies of the ground vibrational state were determined from the 87 ground state combination differences obtained from the experimental data. Fits of parameters of the Watson hamiltonian with both ground state combination differences and ro–vibrational energy values (line positions) of the (010) vibrational state were made. Parameters of the effective dipole moments of the pure rotational transitions and of the ν2 band are obtained. Line lists (line positions and line strengths) of the pure rotational transitions and transitions belonging to the ν2 band are generated which can be useful for astrophysical and planetological applications.

The HD32S high resolution infrared spectrum was recorded and analyzed in the ν3 fundamental band region (2000–3000 cm − 1 ) with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zurich prototype ZP2001). 1533 transitions (about 3.4 times more compared to 446 transitions in earlier studies) were assigned to the ν3 band in the experimental spectra. For the first time, an analysis of the line strengths of this band was made and effective dipole moment parameters were obtained. A special analysis was performed with the goal to obtain the partial pressures of all components (HDS, D2S, H2S, H2O, D2O, HDO, CO2) presented in the sample. A line list of the transitions and strengths of the ν3 band has been generated.

The line strengths of 1572 transitions of the ν ˜ 2 band of the 34SO2 isotopologue centered at 513.5387 cm − 1 were determined using high resolution Fourier Transform Infrared (FTIR) spectroscopy and analyzed with the Hartmann–Tran profile. The line strength data of individual lines were applied then in a fit of parameters of the effective dipole moment operator. Isotopic relations for the dipole moment parameters were derived and used for the fit procedure. The parameters obtained reproduce the initial line strengths with a root mean square deviation d r m s = 4.5 % . A list of 7777 experimental transitions of 34SO2 is generated together with the presentation of their individual line strengths predicted on the basis of the effective dipole moment parameters obtained from the fit.

The spectra of germane 72GeH4 enriched up to 99.9% in the sample were recorded with high resolution (0.003 cm − 1 ) at different pressures with the Bruker IFS 125HR Fourier transform spectrometer (Nizhny Novgorod, Russia). The region of 700–4400 cm − 1 , where the Dyad and Pentad are located, was theoretically analyzed. The 9112 transitions belonging to the seven “cold” bands (6761 transitions) of the Dyad and Pentad and to the nine “hot” Dyad–Pentad bands (2351 transitions) were assigned and analyzed with an effective hamiltonian model which takes into account the presence of resonance interactions. The obtained set of 53 fitted parameters reproduces the initial 9112 experimental line positions with a d r m s = 2.44 × 10 − 4 cm − 1 .

The high resolution infrared spectra of MSiD4 ( M = 29 , 30 ) in natural abundance of MSi (92.23% of 28Si, 4.68% of 29Si, and 3.09% of 30Si) were measured with Bruker IFS120 and IFS125 HR Fourier transform infrared spectrometers at an optical resolution between 0.00096 and 0.0025 cm − 1 and analyzed in the regions of 550–800 cm − 1 and 1480–1700 cm − 1 where the four fundamental bands, ν2, ν4, ν1 and ν3 are located. The 840/1641/888 transitions with Jmax. = 31/31/35 and 638/1356/838 transitions with Jmax. = 31/31/34 were assigned to the ν2, ν4, and ν3 bands of 29SiD4 and 30SiD4. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes the resonance interactions between pairs of vibrational states (0010, F2)/(1000, A1) and (0001, F2)/(0100, E) into account. As a result, sets of 22 and 22 fitted parameters were obtained which reproduces the initial 3369 and 2832 ro–vibrational transitions of the 29SiD4 and 30SiD4 isotopologues with the d r m s = 2.34 × 10 − 4 cm − 1 and 2.67 × 10 − 4 cm − 1 , respectively. An analysis of 221 and 134 experimental ro–vibrational lines of the ν4/ν2 and ν3 bands of 29SiD4 and 30SiD4 was performed using the Hartmann–Tran profile to simulate the measured line shape and to determine experimental line intensities. A detailed line list of transitions of 29SiD4 and 30SiD4 in the studied regions is generated.

The high resolution infrared spectra of dideuterated hydrogen sulfide D2S were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zurich prototype ZP2001) and analyzed in the ν2 fundamental band region, 750–1200 cm − 1 . The 1742 transitions (which is more than two times more than in the preceding analogous studies) were assigned in the experimental spectra to the ν2 band (the maximum values of the quantum numbers are J max = 30 and K a max = 21 ). The subsequent weighted fit of experimentally assigned transitions was made with the Watson Hamiltonian, resulting in a set of 34 parameters which reproduces the initial 535 infrared ro–vibrational energy values from 1742 experimental line positions with a root mean square deviation d r m s = 1.31 × 10 − 4 cm − 1 . An analysis of 280 experimental ro–vibrational line intensities (324 transitions) of the ν2 band was made using the Hartmann–Tran profile of individual lines, and the results were applied then in the fit of parameters of the effective dipole moment operator. Isotopic relations for the dipole moment parameters were derived and used for the fit procedure. The obtained “model dependent” parameters reproduce the initial line strengths with the d r m s = 2.5 % . A list of 1742 experimental transitions of D2S is generated together with the presentation of their individual line strengths calculated on the basis of the obtained effective dipole moment parameters.

Individual strengths of 358 ( J max = 28 ) ro-vibrational lines of the ν3 band of 28SiD4 were obtained from an experimental Fourier transform spectrum by the fit of their shapes with the Hartmann–Tran line profile. They were used in the weighted fit for determination of the effective dipole moment parameters of the ν3 band. Three effective dipole moment parameters were obtained which reproduce the experimental line strengths with the d r m s = 4.0 % . A list of 8125 transitions of the ν3 band with their line strengths was calculated up to J = 43 . The half-widths analysis was made on the basis of the multi-spectrum fit with the Hartmann–Tran line profile. Self line broadening coefficients were estimated for 72 isolated lines of the ν3 band.

The spectra of germane enriched up to 99.9 % of 73GeH4 were recorded with a high resolution (0.003 cm − 1 ) at different pressures with the Bruker IFS 125HR Fourier transform spectrometer (Nizhny Novgorod, Russia) in the region of 650–4400 cm − 1 and analyzed in the Dyad and Pentad region. The 9208 transitions belonging to the seven “cold” bands (6987 transitions) of the Dyad and Pentad and to the nine “hot” Dyad–Pentad bands (2221 transitions) were assigned and theoretically analysed in the frame of the effective Hamiltonian model. The obtained set of 68 fitted parameters reproduces the initial 9208 experimental line positions with the d r m s = 2.82 × 10 − 4 cm − 1 .

The strengths of 619 experimentally recorded spectral lines (Jmax = 24) of the ν4 and ν2 bands of 28SiD4 were determined from the fit of their line shapes with a Hartmann–Tran line profile and were used then in the weighted fit for determination of the effective dipole moment parameters of these bands. The obtained set of four parameters reproduce the initial experimental line intensities with the d r m s = 5.61 % . A list of transitions with their line intensities is generated up to the value of quantum number J = 37 . The half–widths analysis was made on the basis of the multi–spectrum fit with the Hartmann-Tran line profile, and self–pressure broadening coefficients were estimated for 60 lines of the dyad.

The high–resolution Fourier–transform spectrum of C2D4 was recorded at the optical resolution of up to 0.00096 cm − 1 and analyzed in the region of 460–710 cm − 1 , where the whole ν10 band was considered including P, Q and R branches. The experimentally recorded line positions (5040 experimental lines with J max . = 47 and K a max . = 27 ) are theoretically analyzed, and effective spectroscopic parameters are derived from the corresponding fit procedures. The 1247 ro–vibrational energies of the ( v 10 = 1 ) vibrational state are reproduced by a set of 47 fitted spectroscopic parameters with the d r m s = 2.2 × 10 − 4 cm − 1 . Line list of the ro–vibrational transitions of the ν10 band is presented in the Supplementary material.

The high resolution infrared spectra of SiD4 were recorded with Bruker IFS120 and IFS125 HR Fourier transform infrared spectrometers at an optical resolution of 0.002 and 0.0021 cm − 1 and analyzed in the region of 1480–1700 cm − 1 where the stretching bands ν3 and ν1 are located. The 2676 transitions with Jmax. = 44 were assigned to the ν3 band.The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes the resonance interactions between the (0010) and (1000) vibrational states into account. As the result, a set of 18 fitted parameters was obtained which reproduces the initial 2676 ro–vibrational transitions with the d r m s = 3.71 × 10 − 4 cm − 1 .

The high resolution infrared spectra of SiD4 were recorded with a Bruker IFS125 HR Fourier transform interferometer and analysed in the region of 550–800 cm − 1 where the bands ν4 and ν2 are located. The 7279 transitions with Jmax. = 37 were assigned to the ν4/ν2 dyad (the ν2 band is forbidden in absorption for symmetry reasons, and its transitions can appear in the spectrum only because of Coriolis interaction with the allowed ν4 band). The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes the resonance interactions between the (0001) and (0100) vibrational states into account. The initial values of the Hamiltonian parameters have been predicted on the basis of the isotopic substitution theory. As the result, a set of 33 fitted parameters was obtained which reproduces the initial 7279 ro–vibrational transitions with the d r m s = 1.85 × 10 − 4 cm − 1 which corresponds to the experimental uncertainties.

The high-resolution infrared spectra of C2HD3 ethylene was analyzed for the first time in the region of 1230–1340 cm − 1 , where the strong ν12 band is located. The 1748 transitions with the maximum values of the upper quantum numbers J m a x . = 43 and K a m a x . = 14 were assigned to the ν12 band. The 14 transitions have been assigned to the 2ν10 band whose appearance is caused by the strong resonance interaction with the ν12 one. For description of the assigned transitions (upper ro-vibrational energy levels), the effective Hamiltonian was used which takes resonance interactions between the vibrational state ( v 12 = 1 ) and three other closely located states, ( v 10 = 2 ) , ( v 7 = v 10 = 1 ) and ( v 4 = v 10 = 1 ) into account. A set of 70 spectroscopic parameters obtained from a weighted least square fit reproduces the initial experimental data (593 upper energy values, 1762 transitions) with the drms= 1.3 × 10 − 3 cm − 1 . Finally, the strengths of 106 ro–vibrational lines of the ν12 band were roughly estimated.

The high resolution infrared spectra of hydrogen sulfide, H2MS ( M = 32 , 33 , 34 , 36 ) in the natural abundance (95.041% of H232S, 0.748% of H233S, 4.196% of H234S and 0.015% of H236S), were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zurich prototype ZP2001) and analyzed in the ν2 fundamental band region (700 – 1800 cm − 1 ). In the experimental spectra 1564, 1019, and 685 transitions were assigned to the ν2 bands of H232S, H234S and H233S (the maximum values of the quantum numbers are J m a x . / K a m a x . = 24/17, 20/14, 17/14). The subsequent weighted fits of experimentally assigned transitions were made with the Watson Hamiltonian and a set of parameters which reproduces the initial 333/249/216 infrared ro-vibrational energy values has been obtained from the assigned experimental line positions with the root mean square deviations of d r m s = 2.2 × 10 − 4 cm − 1 , 1.7 × 10 − 4 cm − 1 and 1.5 × 10 − 4 cm − 1 for the H232S, H234S and H233S isotopologues. Additionally, 703, 182 and 23 transitions with the values of quantum numbers J m a x . / K a m a x . = 18/14, 14/8 and 9/6 belonging to the 2 ν 2 − ν 2 hot bands of H232S, H234S and H233S (for the first time for the hot bands of the H234S and H233S species) were assigned in the experimental spectra. Rotational parameters of the ground vibrational state of H236S were re-determined, and, for the first time, 103 transitions ( J m a x . = 11 , K a m a x . = 8 ) of the ν2 band of H236S were assigned in the experimental spectra. An analysis of ro-vibrational line strengths of 61 experimental isolated unsaturated and not too weak lines of the ν2 band of H232S was made ( J m a x . = 9 , K a m a x . = 8 ), and five effective dipole moment parameters were obtained from the fit which reproduce the initial experimental line intensities with the drms = 1.4 %. An analogous analysis was performed for the H234S and H233S isotopologues. The half-widths analysis was made on the basis of the multi-spectrum fit with the Hartmann-Tran line profile, and self-pressure broadening coefficients were estimated for a few tens of lines for the three most abundant isotopologues.

Rotational operators of the SO(3) group and corresponding irreducible rotational operators of the Td point group up to the 8th rank are determined for molecules of spherical top type based on the formalism of irreducible tensorial operators.

We report high resolution Fourier Transform Infrared (FTIR) spectra of nitrogen trifluoride (trifluoroamine, NF3) measured with the Zurich Bruker prototype spectrometer (ZP 2001) and the SLS THz/FTIR setup (2009 prototype) in the range 20–3000 cm - 1 at temperatures between 80 and 120 K using a collisional cooling cell designed with White cell multipath reflection optics and at room temperature (296 K). Except in the far-infrared with instrument limited resolution ( Δ ν FWHM = 0.0008 cm - 1 ) many of the spectra are nearly Doppler limited. Rovibrational transitions were assigned to 13 different vibrational bands and were used then in the fitting procedure. We re-investigated the bands 2 ν 4 , ν 1 , ν 2 + ν 4 , ν 1 + ν 4 , 2 ν 3 and ν 1 + ν 3 , which had been studied before, and we have analyzed the ν 2 + ν 3 , 2 ν 1 , ν 1 + ν 2 + ν 4 , ν 1 + ν 2 + ν 3 , ν 2 + 2 ν 3 , 3 ν 3 , ν 1 + 2 ν 3 bands for the first time. All our analyses refer to the isotopomer 14 NF3.

The hot 2ν2 + ν3 – ν2 hybrid band of the S18O16O molecule is assigned in the range 1800–1900 cm–1 for the first time. The spectrum is analyzed based on the method of combination differences. 56 energy levels (Jmax = 15, $$ {\mathrm{K}}_{\mathrm{a}}^{\mathrm{max}}=12 $$ ) are determined based on the experimental data obtained. Rotational parameters of the (021) vibrational state are determined.

The high resolution infrared spectra of sulfur dioxide (32S16O2) were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zurich prototype ZP2001) in combination with a Ge:Cu detector and analyzed in the ν2 fundamental band region (400–650 cm − 1 , ν 0 ˜ = 517.8725691 ( 77 ) cm − 1 ). More than 4200 transitions were assigned in the experimental spectra to the ν2 band (the maximum values of the quantum numbers are J m a x . = 96 and K a m a x . = 25 ). The subsequent weighted fit of experimentally assigned transitions was made with the Watson Hamiltonian. The 148 highly accurate MW transitions known from the literature have been also taken into account in the fit, resulting in a set of 33 parameters which reproduces the initial 1295 infrared ro–vibrational energy values from more than 4200 experimental line positions with a root mean square deviation d r m s = 1.5 × 10 − 4 cm − 1 . An analysis of 992 experimental ro–vibrational line intensities of the ν2 band was made, and a set of four effective dipole moment parameters was obtained which reproduces the initial experimental line intensities with a relative d r m s = 5.7 % . The half-widths of 146 ro-vibrational lines ( J m a x . = 53 and K a m a x . = 20 ) were analyzed from the multi-spectrum fit, and self-pressure broadening coefficients were determined.

We report high-resolution ( 0.001 cm−1) Fourier Transform Infrared spectra of fluoroform (CHF3) including the pure rotational (far infrared or THz) range (28–65 cm−1), the ν3 fundamental ( = 700.099 cm−1), as well as the associated “hot’ band 2ν3 − ν3 ( = 699.295 cm−1) and the ‘atmospheric window’ range 1100–1250 cm−1 containing the strongly coupled polyad of the levels ν2, ν5 and ν3 + ν6, at room temperature and at 120 K using the collisional cooling cell coupled to our Bruker IFS 125 HR prototype (ZP2001) spectrometer and Bruker IFS 125 HR ETH-SLS prototype at the Swiss Light Source providing intense synchrotron radiation. The pure rotational spectra provide new information about the vibrational ground state of CHF3, which is useful for further analysis of excited vibrational states. The ν3 fundamental band is re-investigated together with the corresponding ‘hot’ band 2ν3 − ν3 leading to an extension of the existing line lists up to 4430 transitions with = 66 for ν3 and 1040 transitions with =...

The infrared spectra of SiD 4 in natural abundance were measured in the region of 350–2050 cm − 1 with a Bruker IFS 125HR Fourier transform interferometer at an optical resolution of 0.0021 and 0.0016 cm − 1 and analyzed. Not less than 6490 transitions with J max = 33 were assigned for the first time to the bands 2 ν 4 , ν 2 + ν 4 , and 2 ν 2 of the 28 SiD 4 molecule. Numerous “hot” dyad–pentad transitions (in general, 5545 “hot” transitions) were also assigned for the first time in the region of 600–760 cm − 1 . Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters for the ( 0002 , F 2 ) , ( 0002 , E ) , ( 0002 , A 1 ) , ( 0101 , F 2 ) , ( 0101 , F 1 ) , ( 0200 , A 1 ) and ( 0200 , E ) vibrational states were determined from the fit of experimental line positions. The obtained set of 69 fitted parameters reproduces the initial experimental data with an accuracy of d rms = 3.12 × 10 − 4 cm − 1 for the 6490 “cold” transitions and d rms = 2.33 × 10 − 4 cm − 1 for the 5545 “hot” transitions. Results of the analogues analysis for the 29 SiD 4 and 30 SiD 4 isotopologues with 403/136 “cold” and 171/99 “hot” assigned transitions are presented also.

High resolution infrared spectra of PH 3 were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.0025 cm − 1 and analyzed in the region of 600–1700 cm − 1 where the ν 2 / ν 4 bending dyad is located. The number of 2207 and 4564 transitions (in general, 3099 “allowed” and 3672 “forbidden”, which is about 2.5 times higher in comparison with the preceding studies) with J max = 29, K max = 28 ( J max = K max = 24 in the earlier studies) were assigned to these two bands. Ground state parameters were improved on the basis of MW and IR data, known from the literature, and new IR data from the present study. The A 1 / A 2 splittings for the states with the quantum number K = 13 were experimentally recorded and theoretically explained for the first time. The weighted fit of 1284 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account resonance interaction between the ( 0100 , A 1 ) and ( 0001 , E ) vibrational states. As the result, a set of 86 fitted parameters was obtained which reproduces the initial 1284 upper “experimental”ro–vibrational energy values with the d rms = 9.8 × 10 − 5 cm − 1 .

The high resolution infrared spectra of the 32S16O18O molecule were recorded for the first time with a Bruker IFS 120 HR Fourier transform interferometer and analysed in the region of 1550–1950 cm−1 where the bands ν 1 + ν 2 and ν 2 + ν 3 are located. About 1050 and 1570 transitions were assigned in the experimental spectra with the maximum values of quantum numbers J max . / K a max . equal to 64/16 and 58/19 to the bands ν 1 + ν 2 and ν 2 + ν 3 , respectively. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the studied vibrational states. As the result, a set of 16 fitted parameters was obtained which reproduces the initial 1442 ro-vibrational energy values obtained from the assigned transitions with the d rms = 3.7 × 10 − 4 cm − 1 . An analysis of more than 4050 experimental ro-vibrational line intensities of the ν 1 + ν 2 and ν 2 + ν 3 bands of 32S16O2 was made, and a set of 7 effective dipole moment parameters was obtained which reproduce the initial experimental line intensities with the d rms = 6.9 % . Values of these parameters, being re-calculated to the values of corresponding parameters of the 34S16O2, 32S18O2 and 32S16O18O species were used for calculation of line intensities in the ν 1 + ν 2 and ν 2 + ν 3 bands of these three isotopologues. A list of transitions with their line intensities in the region of 1550–1950 cm−1 for the four mentioned species is generated.

The infrared spectra of SiH4 in natural abundance (92.23% of 28SiH4, 4.68% of 29SiH4, and 3.09% of 30SiH4) were measured in the region of 600–1200 cm−1 with a Bruker IFS 120HR Fourier transform spectrometer, analyzed and compared with the results available in the literature. More than 3500 transitions with J max . = 27 were assigned to the dyad bands ν4 and ν2 of 28SiH4 (the band ν2 is allowed in Raman, but forbidden in absorption spectra for symmetry reasons, and its transitions appear in absorption spectra only because of strong Coriolis interaction with the ν4 band). Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters for the ground, (0100) and (0001) vibrational states were determined from the fit of experimental line positions. The obtained set of parameters reproduces the initial experimental data with accuracy close to experimental uncertainties. The results of the analogous analyses of the 29SiH4 and 30SiH4 isotopologues are also presented (the numbers of the assigned transitions are here more than 1360 and 1120). An further analysis of about 790 experimental ro-vibrational lines in the dyad region of 28SiH4 was performed using the Voigt profile to simulate the measured line shape and to determine experimental line intensities. A set of 4 effective dipole moment parameters for the dyad of 28SiH4 was obtained on that basis from the weighted fit, which reproduce the initial experimental intensities of about 790 lines with the d rms = 5.6 % . Analogous analyses were made for the two other isotopic species, 29SiH4, and 30SiH4. A detailed line list of transitions in the region of 750–1150 cm−1 is generated. The half-widths of 40 ro-vibrational lines ( J up . max . = 16 ) are studied from the multi-spectrum analysis, and self-pressure broadening coefficients are determined.

The second bending overtone band 3ν2 of sulfur dioxide has been studied for the first time with high resolution rotation-vibration spectroscopy. The 1530 transitions involving 728 upper state energy levels with Jmax.= 53 and K a m a x . = 15 have been assigned to the 3ν2 band. The 746 transitions belonging to the 3 ν 2 − ν 2 “hot” band have been also assigned in the region of 950–1100 cm − 1 . For the analysis of the assigned transitions, an effective Hamiltonian of an isolated (030) vibrational state (the Watson operator in A-reduction and Ir representation) was used. Set of 9 varied parameters was determined which reproduce the initial experimental data with the drms deviations of 9.0 × 10 − 4 cm − 1 and 9.8 × 10 − 4 cm − 1 for the 3ν2 and 3 ν 2 − ν 2 bands, which are comparable with the experimental uncertainties.

The high resolution (0.0021–0.0025 cm − 1 ) infrared spectra of SiH4 in natural abundance (92.23 % of 28SiH4, 4.68 % of 29SiH4, and 3.09 % of 30SiH4) were measured in the 2000–2350 cm − 1 region with a Bruker IFS 120HR Fourier transform spectrometer. The 2584 transitions with Jmax. = 27 were assigned to the ν3 and ν1 bands of 28SiH4. Rotational, centrifugal distortion, tetrahedral splitting, and resonance interaction parameters for the (0010) and (1000) vibrational states were determined from the weighted fit of experimental line positions. The obtained set of parameters reproduces the initial experimental data with an accuracy close to experimental uncertainties. The results of analogous analyses of the 29SiH4 and 30SiH4 isotopologues (the numbers of assigned transitions are 811 and 986 both with Jmax. = 23) were made with the use of the isotopic substitution theory relations. A further analysis of 379 experimental ro-vibrational lines of the ν3 and ν1 bands of 28SiH4 was performed using the Hartmann–Tran profile to simulate the measured line shape and to determine experimental line intensities. The 4 effective dipole moment parameters were obtained on that basis from the weighted fit, which reproduce the initial experimental intensities of the 379 initial lines (both strong and weak) with the d r m s = 7.6 % (the 148 strongest lines are reproduced with the d r m s = 5.0 % ). Analogous analyses were made for the two other isotopic species, 29SiH4, and 30SiH4. A detailed line list of transitions in the region of 2000–2350 cm − 1 is presented. The half-widths of 100 ro-vibrational lines ( J u p . m a x . = 17 ) are analyzed from the multi-spectrum fit, and self-pressure broadening coefficients are determined.

High–resolution (0.004 cm − 1 ) Fourier transform spectra of the 15NH2D molecule were recorded for the first time in the region of 1000–1800 cm − 1 at LISA in Creteil and analyzed. Assignments of transitions were made on the basis of the Ground State Combination Differences method. Parameters of the effective Hamiltonian of the ground vibrational state in the model of the asymmetric top molecule in A − reduction and I r − representation were determined from the fit of MW and FIR data known in the literature. As a result of the analysis, about 4380 ro-vibrational transitions have been assigned to the five vibrational states ( v 5 = 1 , s ) , ( v 5 = 1 , a ) , ( v 6 = 1 , s ) , ( v 6 = 1 , a ) , and ( v 2 = 2 , s ) , and the values of 647 upper ro-vibrational energy levels were determined. A weighted fit was carried out using the model of the effective Hamiltonian which takes into account strong resonance interaction between all five upper vibrational states corresponding to the observed ( v 5 = 1 , s ) , ( v 5 = 1 , a ) , ( v 6 = 1 , s ) , ( v 6 = 1 , a ) , and ( v 2 = 2 , s ) , and interaction of these five states with an unobserved sixth state ( v 2 = 2 , a ) . A set of 168 parameters obtained from the fit provided the basis to reproduce the initial 647 energy values (line positions of about 4380 transitions) of the five mentioned inversion–vibrational states with the d r m s = 7.9 × 10 − 4 cm − 1 .

The rotational structure of the (111) and (021) vibrational states is determined for the first time from the high resolution analysis of the ν 1 + ν 2 + ν 3 − ν 2 and 2 ν 2 + ν 3 − ν 2 “hot” bands. The 480 and 74 transitions of these bands ( J max / K a max = 45/14 and 15/12 respectively) were assigned in the spectra, which have been recorded with the Bruker IFS 120 Fourier transform infrared (FTIR) spectrometer. A weighted fit analysis allowed us to generate a set of 5 fitted parameters for the (111) state and 4 fitted parameters for the (021) state. Calculation with the 9 parameters, obtained from the fit, reproduces the initial 363 energy values (about 550 assigned experimental transitions) of two vibrational states with the drms deviations of 3.2 × 10 − 4 cm − 1 , which is comparable with the experimental uncertainties of very weak transitions of the ν 1 + ν 2 + ν 3 − ν 2 and 2 ν 2 + ν 3 − ν 2 “hot” bands in our experiment.

Transitions belonging to the three “hot” bands of the S 18 O 2 molecule, ν 1 + ν 2 + ν 3 − ν 2 (621 transitions with the values of quantum numbers J max = 49 and K a max = 14 ), 2 ν 1 + ν 2 − ν 2 (332 transitions with J max = 42 and K a max = 12 ) and 2 ν 2 + ν 3 − ν 2 (15 transitions with J max = 14 and Ka=8 and 9), were assigned in the spectral 2100–2700 cm−1 region. This enabled for the first time to get high accurate values of 388, 185 and 13 ro-vibrational energies for the highly excited vibrational states (111), (210) and (021), respectively. A weighted fit analysis using the obtained ro-vibrational energies allowed us to generate a set of 20 fitted parameters which reproduce the initial 586 energy values (about 970 assigned experimental transitions) with the drms deviations of 1.9 × 10 − 4 cm − 1 , 2.8 × 10 − 4 cm−1 and 2.5 × 10 − 4 cm−1 for the states (111), (210) and (021).

We report high resolution ( δ ν ⩽ 0.001 cm - 1 ) Fourier Transform Infrared (FTIR) spectra of the trifluoromethane (fluoroform) isotopomer 13 CHF 3 including results from synchrotron based spectroscopy at the Swiss light source (SLS). The analysis is extended to the pure rotational spectra in the Terahertz (far-infrared) range (15–100 cm−1, δ ν FWHM = 0.0006 cm - 1 ), the ν 3 fundamental ( ν 0 = 695.292 cm - 1 ), the associated “hot” band 2 ν 3 - ν 3 providing information on the level 2 ν 3 ( ν 0 = 1389.807 cm - 1 ) and the ν 4 fundamental ( ν 0 = 1369.013 cm - 1 ) coupled to 2 ν 3 . The results are discussed in relation to the 13 C isotope effect on the vibrational quantum dynamics as derived by theory and in relation to fluoroform as a greenhouse gas.

The high resolution infrared spectra of the 32S16O18O molecule were recorded with a Bruker IFS 120 HR Fourier transform interferometer for the first time in the region of 1800–2800 cm−1 where the bands 2ν1, ν 1 + ν 3 , and 2ν3 are located. About 3970, 2960 and 3450 transitions were assigned in the experimental spectra with the maximum values of quantum numbers J max . / K a max . equal to 59/20, 68/25, and 43/18 to the bands 2ν1, ν 1 + ν 3 , and 2ν3, respectively. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the studied vibrational states. As the result, a set of 39 fitted parameters was obtained which reproduces the initial 3213 ro-vibrational energy values obtained from the assigned transitions with the d rms = 2.4 × 10 − 4 cm − 1 .

A method is presented which allows one to derive partial pressures of isotopologue molecules in a gaseous mixture under the conditions of rapid isotope exchange. For this purpose, isotopic relations between effective dipole moment parameters of a “parent” molecule and its related isotopically substituted species are derived on the basis of the general isotopic substitution theory. The efficiency of the method is illustrated. The result was derived for the fundamental bands and is valid for any asymmetric top molecule. The discussed general consideration offers the possibility to obtain analogous results both for any overtone as well as combinational bands of any asymmetric top molecule, and (with minor corrections) for any symmetric and/or spherical top molecule. The validity and efficiency of the general results are confirmed by comparison of the general results obtained in the present paper with the experimental results for the H2O/HDO molecules with a deviation of 3 to 4%.

The high resolution infrared spectra of SiH 4 in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm − 1 and analyzed in the region of 1600–2100 cm − 1 where the first bending overtone 2 ν 2 , 2 ν 4 and combinational ν 2 + ν 4 bands are located. A line strength analysis of the 2018 (1636/211/171) experimentally recorded transitions of the 28 SiH 4 , 29 SiH 4 , and 30 SiH 4 species was made by the fit of their line shapes with the Hartmann-Tran profile and 9 effective dipole moment parameters (7/1/1 fitted parameters for the 28 SiH 4 , 29 SiH 4 and 30 SiH 4 species, respectively) were obtained from the weighted fit which reproduce initial experimental line strengths of 28 SiH 4 , 29 SiH 4 and 30 SiH 4 with the d rms = 3.65 % , 3.77 % and 3.46 % . Self–broadening coefficients of 1064 lines (typically lying between (8 and 10) × 10 − 2 cm − 1 · atm − 1 ) and self–shift coefficients of 785 lines (typically lying between (5 and 10) × 10 − 3 cm − 1 · atm − 1 ) of all three isotopologues of silane were determined from the multi–spectrum analysis of these lines.

For the 12 C 2 H 2 D 2 -cis molecule a line strength analysis of 1473/400 transitions of the ν 12 / ν 3 bands was performed by the fit of their line shapes with the Hartmann–Tran profile. Ten effective dipole moment parameters (six parameters for the ν 12 band and four parameters for the ν 3 band) were obtained from the weighted fit which reproduce the initial experimental 1473 transition strengths of the ν 12 band with the d rms = 3.11 %. For the very weak ν 3 band 400 experimental transitions are reproduced with the d rms = 7.72 %. The results of the analysis are presented as the Supplementary material to this paper.

The high resolution infrared spectra of GeH 4 in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm − 1 and analyzed in the region of 1400–2000 cm − 1 where the first bending overtone 2 ν 2 , 2 ν 4 and combinational ν 2 + ν 4 bands are located. Ro–vibrational line positions and energies of the 70 GeH 4 species were analysed for the first time and line positions and energies of the 72 GeH 4 and 74 GeH 4 species were improved considerably in comparison with the preceding studies. The numbers of 2316/2406/873/3007/2257 transitions with J max = 21/23/18/22/19 of the 2 ν 2 ( A 1 − and E − type sub–bands), 2 ν 4 ( A 1 − , E − and F 2 − type sub–bands) and ν 2 + ν 4 ( F 1 − and F 2 − type sub–bands) bands of the 70 GeH 4 , 72 GeH 4 , 73 GeH 4 , 74 GeH 4 , and 76 GeH 4 molecules were used in the joint weighted fit of experimentally assigned transitions with the Hamiltonian model which takes the resonance interactions between the seven, ( 0200 , A 1 ) , ( 0200 , E ) , ( 0101 , F 1 ) , ( 0101 , F 2 ) , ( 0002 , A 1 ) , ( 0002 , E ) and ( 0002 , F 2 ) , vibrational states into account. From our preceding studies 5563 hot band transitions were also taken into account. As the result of a joint fit, a set of 129 fitted parameters was obtained which reproduce the initial 16422 experimental (including “hot”) transitions of five isotopologues with the d rms = 3.26 × 10 − 4 cm − 1 . A line strength analysis of the 1697 experimentally recorded transitions of all species was made by the fit of their line shapes with the Hartmann-Tran profile and 13 effective dipole moment parameters were obtained from the weighted fit which reproduce the initial experimental line strengths with the d rms = 3.4 % . Self–broadening coefficients of 993 lines and self–shift coefficients of 674 lines were determined from the multi–spectrum analysis of these lines.

High-resolution FTIR ro-vibrational spectra of the 13C12CH4 molecule in the region of 600–1700 cm−1, where the bands ν3, ν12 and ν2 are located, were recorded and analyzed with the Hamiltonian model. This model takes resonance interactions between these three bands as well as strong interactions with six neighboring bands, ν10, ν8, ν7, ν4, ν6, and 2ν10 into account. More than 3800 ro-vibrational transitions belonging to the bands ν3, ν12, ν2 and 2ν10 were assigned (for the first time for the ν2, ν3 and 2ν10 bands) with the maximum values of quantum numbers J max . / K a max . equal to 22/8, 52/18, 30/11 and 27/12, respectively. On this basis, a set of 62 vibrational, rotational, centrifugal distortion and resonance interaction parameters was obtained from the weighted fit. These parameters reproduce 1562 initial “experimental” ro-vibrational energy levels obtained from unblended lines with the rms error d rms = 2.6 × 10 − 4 cm − 1 . Furthermore, ground state parameters of the 13C12CH4 molecule were improved.

The two strongest absorption “hot” bands of C 2 D 4 , ν 7 + ν 10 − ν 10 and ν 10 + ν 12 − ν 10 were analyzed for the first time on the basis of high resolution infrared spectra recorded with a Bruker high resolution Fourier transform spectrometer. About 740 and 550 transitions (233 and 174 upper state ro-vibrational energy values) with J max . = 25 , K a max = 18 and J max . = 20 , K a max . = 10 for the bands ν 7 + ν 10 − ν 10 and ν 10 + ν 12 − ν 10 were assigned. The obtained upper ro-vibrational energies were used then in the weighted fit of parameters of the effective Hamiltonian which takes into account resonance interactions between the vibrational states ( v 7 = v 10 = 1 ) and ( v 10 = v 12 = 1 ) , on the one hand, and eight other closely located vibrational states, on the other hand. A set of 46 varied parameters was obtained from the fit, which reproduces the initial experimental data with the rms deviation of 2.5 × 10 − 4 cm − 1 and which is close to experimental uncertainties.

We report a comparison of the analysis of the low energy spectrum of 13CHF3 and 12CHF3 from the THz (FIR) range to the ν1 fundamental at high resolution (δ[small nu, Greek, tilde] < 0.001 cm-1 or otherwise Doppler limited) on the basis of FTIR spectra taken both with ordinary light sources and with the synchrotron radiation from the Swiss Light Source. Several vibrational levels are accurately determined including, in particular, the 2ν4 CH-bending overtone and the ν1 CH-stretching fundamental of 13CHF3. Comparison of experimental results with those from accurate full dimensional vibrational calculations allows for a study of the time-dependent quantum dynamics of intramolecular vibrational redistribution (IVR) in the CH chromophore both on short time scales (fs) and longer time scales (ps) when coupling to the lower frequency modes becomes important and where the 12C/13C isotope effects are very large.

We report the results of a highly accurate, (1–3)×10−4 cm−1, ro-vibrational analysis of the S18O2 molecule in the spectral region of 2100–2700 cm−1. More than 2910, 2130, and 1390 transitions belonging to the 2ν1, ν 1 + ν 3 , and 2ν3 bands were assigned for the first time with the values of quantum numbers J max . / K a max . equal to 67/26, 81/25 and 53/16, respectively. The weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account Coriolis resonance interactions between the vibrational states ( v 1 v 2 v 3 ) and ( v 1 ∓ 1 v 2 v 3 ± 1 ) and Fermi interactions between the states ( v 1 v 2 v 3 ) and ( v 1 ∓ 1 v 2 ± 2 v 3 ) . To make the ro-vibrational analysis physically more suitable, the initial values of main spectroscopic parameters have been estimated theoretically. Finally, the set of 43 spectroscopic parameters obtained from the fit reproduces values of 2384 initial “experimental” ro-vibrational energy levels (more than 6430 transitions assigned in the experimental spectra) with the rms = 1.74 × 10 − 4 cm − 1 .

The high resolution IR spectrum of the trans-d2-ethylene (trans-C2H2D2) was recorded and analyzed in the region of 1450–1750 cm−1, where the strongly interacting bands ν 8 + ν 10 , ν 7 + ν 8 , ν 6 + ν 10 , and ν 6 + ν 7 are located (one of the sub-bands of the hybrid ν 7 + ν 8 band was analyzed earlier; transitions belonging to the three other bands were experimentally recorded and assigned in the present study for the first time). For description of the upper ro-vibrational energy levels obtained from the assigned transitions, the used Hamiltonian takes into account resonance interactions both between four studied vibrational states, ( v 8 = v 10 = 1 ) , ( v 7 = v 8 = 1 ) , ( v 6 = v 10 = 1 ) , ( v 6 = v 7 = 1 ) , and between the state ( v 6 = v 7 = 1 ) and the additional fifth state ( v 4 = v 8 = 1 ) which is considered in the present study as a “dark” state. About 2360, 2150, 2020 and 1700 transitions with the values J max . / K a max . =31/21, 44/18, 28/18 and 27/17 were assigned to the bands ν 8 + ν 10 , ν 7 + ν 8 , ν 6 + ν 10 , and ν 6 + ν 7 , respectively. A set of 103 spectroscopic parameters was obtained from a weighted least square fit procedure. This reproduces the 550, 656, 441 and 435 upper ro-vibrational energies of the vibrational states ( v 8 = v 10 = 1 ) , ( v 7 = v 8 = 1 ) , ( v 6 = v 10 = 1 ) and ( v 6 = v 7 = 1 ) used in the fit with a d rms = 2.5 × 10 − 4 cm − 1 , which is close to the value of the mean experimental uncertainty (in this case, only upper energies obtained from unblended and nonsaturated transitions of relatively high intensities have been taken into account).

High-accurate Fourier-transform infrared spectra of C2D4 were recorded and analyzed in the region of 600–1150 cm−1 where the bands ν 7 ( B 1 u ) , ν 10 ( B 2 u ) , ν 12 ( B 3 u ) are located as well as the ν 4 ( A u ) band which is forbidden by the symmetry of the molecule. The ground state rotational structure was re-analyzed by the use of ground state combination differences obtained on the basis of infrared transitions of the ν12 and ν7 absorption bands. This gave us the possibility to considerably improve the rotational and centrifugal parameters of the ground vibrational state. The analysis of the experimental data and the subsequent weighted-fit procedure of the Hamiltonian parameters allowed us to reproduce the initial 4405 “experimental” ro-vibrational energy values with the d rms = 2.1 × 10 − 4 cm − 1 .

The infrared spectra of GeH4 (88.1% of 76GeH4, 11.5% of 74GeH4, and a minor amounts of three other stable isotopic species in the sample) were measured in the region of 1450–2000cm−1 with a Bruker IFS 125HR Fourier transform interferometer (Nizhny Novgorod, Russia) and analyzed. 2254 transitions with Jmax=19 were assigned for the first time to the bands 2ν4(F2), 2ν4(E), ν2+ν4(F2), ν2+ν4(F1), 2ν2(A1) and 2ν2(E) of the 76GeH4 isotopologue. Numerous “hot” Dyad–Pentad transitions also were recorded and assigned for the first time in the region of 700–1080cm−1 (in general, about 1000 transitions). Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters for the (0002,F2), (0002,E), (0002,A1), (0101,F2), (0101,F1), (0200,A1) and (0200,E) vibrational states were determined from the fit of experimental line positions. The obtained set of parameters reproduces the initial experimental data with accuracy close to experimental uncertainties. Results of the analogous analysis of the 74GeH4 isotopologue (the number of assigned transitions is 309 “cold” and 99 “hot” ones) are presented also. Obtained from the weighted fit set of spectroscopic parameters of the effective Hamiltonian reproduces the initial experimental data with the drms better than 3×10−4cm−1.