High resolution spectra of the H232S hydrogen sulfide are re–analysed in the region of its first decade. Thanks to the improvement of the experimental conditions (in particular, an increase in both the instrumental resolution and the effective absorption path length by 1.5 times), on the one hand, and of the use of a more correct Hamiltonian model (which additionally takes into account the interactions of the bands under study with the ν1+4ν2 and 4ν2+ν3 bands), on the other hand, the information obtained as a result of the analysis of experimental data has been significantly expanded and improved compared to the previous status. In particular, (1) the total number of assigned lines has been increased by approximately 15 percent, (2) the maximum values of quantum numbers Jmax and Kamax for the assigned lines have been increased for the studied bands in average by 20–25 percent, (3) the number of obtained ”experimental“ energy levels of the upper vibrational states (especially for the (121) and (022) vibrational states) has been significantly increased, (4) despite the increase in the number of initial vibrational–rotational energies and quantum numbers Jmax and Kamax, the value of the standard deviation drms has improved 2.7 times for the obtained upper vibrational–rotational energies.

A highly accurate rotational-vibrational analysis of Fourier transform infrared spectra of the 12CD4 molecule is presented. The high resolution infrared spectra were measured with a IFS125 HR Fourier transform interferometer from Bruker at an optical resolution of 0.003 cm(-1) and analyzed in the 1750-2400 cm(-1) region. Here the 2 nu(2), nu(2)+nu(4), 2 nu(4), nu(1) and nu(3) bands (altogether, nine sub-bands of different symmetry) of the pentad are located. The number of 1213/1993/1576/77/1582 transitions with the J(max) = 23/23/23/14/32 were assigned to the 2 nu(2), nu(2)+nu(4), 2 nu(4), nu(1) and nu(3) bands of 12CD4. The obtained experimental data were used for the determination of the upper ro-vibrational energy values. To provide more correct values of the upper energies, more than 7800 highly accurate "hot" transitions from the dyad region were additionally processed. In general, 4088 upper ro-vibrational energies of the pentad (for comparison, 2525 upper ro-vibrational energies with the value of J(max)=20 are known in the modern literature up to now) were determined, which were used then in the weighted fit procedure with a goal to determine the spectroscopic parameters (band centers, rotational, centrifugal distortion, tetrahedral splitting and resonance interaction parameters) of the effective Hamiltonian. The obtained drms value is 5.5x10(-4) cm(-1) which is almost one hundred times better than the reproduction of the same set of experimental data by the parameters known in the earlier literature.

We have started a measurement campaign of numerous methanol isotopologs in low-lying torsional states in order to provide extensive line lists for radio astronomical observations from an adequate spectroscopic model and to investigate how the intricate vibrationtorsion-rotation interactions manifest themselves in the spectra of different isotopic species. After CD3OH and CD3OD, we turn our focus to CH3OD, which is an important species for studying deuteration in prestellar cores and envelopes that enshroud protostars. Notably, deuteration is frequently viewed as a diagnostic tool for star formation. The measurements used in this study were obtained in two spectroscopic laboratories and cover large fractions of the 34 GHz-1.35 THz range. As done in previous studies, we employed a torsion-rotation Hamiltonian model for our analysis that is based on the rho-axis method. The resulting model describes the ground and first excited torsional states of CH3OD well up to quantum numbers J <= 51 and K-a <= 18. We derived a line list for radio astronomical observations from this model that is accurate up to at least 1.35 THz and should be sufficient for all types of radio astronomical searches for this methanol isotopolog in these two lowest torsional states. This line list was applied to a reinvestigation of CH3OD in data from the Protostellar Interferometric Line Survey of IRAS 16293-2422 obtained with the Atacama Large Millimeter/submillimeter Array. The new accurately determined value for the column density of CH3OD implies that the deuteration in methanol differs in its two functional groups by a factor of similar to 7.5.

A highly accurate ro-vibrational analysis of FTIR spectra (line positions of 13CD4 and line strengths of both the 12CD4 and 13CD4 species) is presented. The high-resolution infrared spectra of both molecules were measured with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm−1 and analyzed in the regions of 800–1400 cm−1 where the ν2/ν4 dyad is located. The number of 901 transitions with Jmax=23 were assigned to the ν4 and ν2 bands of 13CD4 (this number is about 5.3 times higher in comparison with the number of known assigned transitions for 13CD4). The weighted fit of experimental line positions was made using the Hamiltonian model which takes into account the resonance interactions between the (0001,F2) and (0100,E) vibrational states. As a result, set of 18 fitted parameters of the (0001,F2)/(0100,E) vibrational states of 13CD4 was determined which reproduce the initial 901 experimental ro–vibrational line positions with the drms=2.59×10−4 cm−1, which is close to the experimental uncertainty of the recorded spectra and about 1330 times better in comparison with the reproduction of the same line position values by the use of parameters from Loëte et al. (1983). The analysis of 1557 experimental lines of the dyad of 12CD4 and 131 lines of the dyad of 13CD4 was fulfilled with the Hartmann–Tran profile to simulate the measured line shape and to determine experimental line intensities. Sets of 6/1 varied effective dipole moment parameters of 12CD4/13CD4 are determined which reproduce the initial 1557/131 line strengths with the drms=4.80% and 4.21%. Lists of the assigned line positions and strengths in the studied region are presented as the Supplementary data to this paper.

A highly accurate ro-vibrational analysis of FTIR spectra (line positions of (CD4)-C-13 and line strengths of both the (CD4)-C-12 and (CD4)-C-13 species) is presented. The high-resolution infrared spectra of both molecules were measured with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm(-1) and analyzed in the regions of 800-1400 cm(-1) where the v(2)/v(4) dyad is located. The number of 901 transitions with J(max) = 23 were assigned to the v(4) and v(2) bands of (CD4)-C-13 (this number is about 5.3 times higher in comparison with the number of known assigned transitions for (CD4)-C-13). The weighted fit of experimental line positions was made using the Hamiltonian model which takes into account the resonance interactions between the (0001, F-2) and (0100, E) vibrational states. As a result, set of 18 fitted parameters of the (0001, F2)/(0100, E) vibrational states of (CD4)-C-13 was determined which reproduce the initial 901 experimental ro-vibrational line positions with the d(rms) = 2.59 x 10(-4) cm(-1), which is close to the experimental uncertainty of the recorded spectra and about 1330 times better in comparison with the reproduction of the same line position values by the use of parameters from Loete et al. (1983). The analysis of 1557 experimental lines of the dyad of (CD4)-C-12 and 131 lines of the dyad of (CD4)-C-13 was fulfilled with the Hartmann-Tran profile to simulate the measured line shape and to determine experimental line intensities. Sets of 6/1 varied effective dipole moment parameters of (CD4)-C-12/(CD4)-C-13 are determined which reproduce the initial 1557/131 line strengths with the d(rms) = 4.80% and 4.21%. Lists of the assigned line positions and strengths in the studied region are presented as the Supplementary data to this paper.

Solar-type prestellar cores and protostars display large amounts of deuterated organic molecules. Recent findings on CHD$_2$OH and CD$_3$OH toward IRAS 16293-2422 suggest that even fully deuterated methanol, CD$_3$OD, may be detectable as well. However, searches for CD$_3$OD are hampered in particular by the lack of intensity information from a spectroscopic model. The objective of the present investigation is to develop a spectroscopic model of CD$_3$OD in low-lying torsional states that is sufficiently accurate to facilitate searches for this isotopolog in space. We carried out a new measurement campaign for CD$_3$OD involving two spectroscopic laboratories that covers the 34 GHz-1.1 THz range. A torsion-rotation Hamiltonian model based on the rho-axis method was employed for our analysis. Our resulting model describes the ground and first excited torsional states of CD$_3$OD well up to quantum numbers $J \leq 51$ and $K_a \leq 23$. We derived a line list for radio-astronomical observations from this model that is accurate up to at least 1.1 THz and should be sufficient for all types of radio-astronomical searches for this methanol isotopolog. This line list was used to search for CD$_3$OD in data from the Protostellar Interferometric Line Survey of IRAS 16293$-$2422 obtained with the Atacama Large Millimeter/submillimeter Array. While we found several emission features that can be attributed largely to CD$_3$OD, their number is still not sufficiently high enough to establish a clear detection. Nevertheless, the estimate of 2$\times 10^{15}$ cm$^{-2}$ derived for the CD$_3$OD column density may be viewed as an upper limit that can be compared to column densities of CD$_3$OH, CH$_3$OD, and CH$_3$OH. The comparison indicates that the CD$_3$OD column density toward IRAS 16293-2422 is in line with the enhanced D/H ratios observed for multiply deuterated complex organic molecules.

The high resolution infrared spectra of CD4 were measured with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm( -1) and analyzed in the region of 80 0-140 0 cm( -1) where the nu(2)/nu(4) dyad is located. The number of 3633 and 1927 transitions with J(max) = 31 and J(max)= 28 were assigned to the nu(4 )and nu(2) bands of CD4 (which is more than three times higher in comparison with the number of assigned transitions known in the literature). The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the upper (0 0 01 , F (2)) and the (0100 , E) vibrational states. As a result, a set of 52 fitted parameters (10 parameters of the ground vibrational state, 19 parameters of the (0 0 01 , F- 2) vibrational state, 9 parameters of the (0100 , E) vibrational state, and 14 resonance interaction parameters) was obtained which reproduces the positions of the initial 5560 experimental rovibrational transitions with the d(rms )= 1 . 83 x 10 (-4) cm(-1) which is close to the experimental uncertainty of the recorded spectra and is about 615 times better in comparison with the reproduction of the same 5560 transition values by the use of parameters from (J. Mol. Spectrosc., 99 , 63 - 86(1983) ). A list of assigned transitions in the studied region is presented as the Supplementary material to this paper. (C) 2022 Elsevier Ltd. All rights reserved.

High resolution infrared spectra of C2H3D were recorded in the region of 550-1950 cm-1 with a Bruker IFS125 HR Fourier transform infrared spectrometers and rotational structures of the five lowest strongly interacting ν10, ν7,ν8,ν4 and ν6 bands were analyzed. The number of about 28000 transitions (4200/6800/5600/5000/6400 for the bands ν10,ν7,ν8,ν4 and ν6) with Jmax = 40 and Kamax = 20 were assigned to these five bands. The weighted fit of 3990 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account resonance interactions between all studied bands as well as with the sixth ν3 band which was considered in this case as a "dark" one. As the result of analysis, a set of 279 fitted parameters was obtained which reproduces the initial 3990 upper "experimental" ro-vibrational energy values with the drms=1.7×10-4 cm-1; the initial nonsaturated, unblended and not very weak of 28000 assigned transitions are reproduced with the drms=2.2×10-4 cm-1. Ground state parameters of the C2H3D molecule were improved as well.

Solar-type protostars have been shown to harbor highly deuterated complex organics, as evidenced, for instance, by the high relative abundances of doubly and triply deuterated isotopologs. While this degree of deuteration may provide important clues in studying the formation of these species, spectroscopic information on multiply deuterated isotopologs is often insufficient. In particular, searches for triply deuterated methanol, CD 3 OH, are hampered to a large extent by the lack of intensity information from a spectroscopic model. The aim of the present study is to develop a spectroscopic model of CD 3 OH in low-lying torsional states that is sufficiently accurate to facilitate further searches for CD 3 OH in space. We performed a new measurement campaign for CD 3 OH involving three spectroscopic laboratories that covers the 34 GHz−1.1 THz and the 20−900 cm −1 ranges. The analysis was performed using the torsion-rotation Hamiltonian model based on the rho-axis method. We determined a model that describes the ground and first excited torsional states of CD 3 OH, up to quantum numbers J ≤ 55 and K a ≤ 23, and we derived a line list for radio-astronomical observations. The resulting line list is accurate up to at least 1.1 THz and should be sufficient for all types of radio-astronomical searches for this methanol isotopolog. This line list was used to search for CD 3 OH in data from the Protostellar Interferometric Line Survey of IRAS 16293−2422 using the Atacama Large Millimeter/submillimeter Array. Specifically, CD 3 OH is securely detected in the data, with a large number of clearly separated and well-reproduced lines. We not only detected lines belonging to the ground torsional state, but also several belonging to the first excited torsional state. The derived column density of CD 3 OH and abundance relative to the non-deuterated isotopolog confirm the significant enhancement of this multiply deuterated variant. This finding is in line with other observations of multiply deuterated complex organic molecules and may serve as an important constraint on their formation models.

Spectra of HBr with a natural abundance of isotopologues were recorded in the region of the first overtone at room temperature at various sub-atmospheric pressures. The coefficients of self-broadening and shifting were found for two isotopologues of HBr. Both broadening and shifting coefficients for different isotopologues coincide within the error margins. The broadening coefficients are in good agreement with those reported previously, however they have a smaller error, about 1%. The shifting coefficients are reported for the first time. The obtained line intensities of both isotopologues are in reasonable agreement with values published earlier.

The photodissociation dynamics of PCl3 at 235 nm has been studied by monitoring ground state Cl(2P3/2) and spin-orbitally excited Cl(2P1/2) atoms by resonance enhanced multiphoton ionization (REMPI). Also, the PCln+ (n = 0, 1, 2) photoions were observed non-resonantly. The speed distributions and speed-dependent anisotropy parameters β for all these particles have been determined by three-dimensional photofragment ion imaging. The β parameters are close to zero for all these particles. The relative yield of excited Cl(2P1/2) atoms for photodissociation of PCl3 is 0.49 ± 0.03. The speed distributions of Cl(2P3/2) and Cl(2P1/2) atoms are bimodal, mainly resulting from the sequential photodissociation PCl3 → PCl2 → PCl. Near-resonant two-photon ionisation followed by near-resonance one-photon photodissociation is proposed for the production of PCln+ photoions. Using Condon's reflection principle, we constructed the vibrational mode dependent absorption spectrum by accounting for the vibrational motion for all six normal coordinates. As a result, the absorption of 235 nm radiation by PCl3 occurs due to zero vibrational motion rather far from the equilibrium geometry. In particular, movement along the Q2 normal coordinate results in an efficient photoinduced transition into the excited state à of D3h symmetry due to a parallel transition.

The high resolution infrared spectrum of di-deuterated hydrogen sulfide D2S was recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and analyzed in the region of 240 0-290 0 cm(-1) where ro-vibrational bands of the so-called second triad of D2S are located. The present study is focused on the line strength analysis of the weak 3 nu(2) band which is made for the first time. The strength analysis comprise 300 lines (376 transitions) with maximum values of the quantum numbers J(max) = 18 and Ka(max) = 9 and was performed by the fit of the experimental line shapes with a Hartmann-Tran profile. The six effective dipole moment parameters of the 3 nu(2) band were obtained from the weighted fit which reproduce the initial experimental line strengths with the d(rms) = 3 . 1% . (C) 2021 Elsevier Ltd. All rights reserved.

Solar-type protostars harbor highly deuterated complex organics. While this degree of deuteration may provide important clues in studying the formation of these species, spectroscopic information on multiply deuterated isotopologs is often insufficient. In particular, searches for triply deuterated methanol, CD_3OH, are hampered by the lack of intensity information from a spectroscopic model. The aim of the present study is to develop such a model of CD_3OH in low-lying torsional states that is sufficiently accurate to facilitate further searches for CD_3OH in space. We performed a new measurement campaign for CD_3OH involving three spectroscopic laboratories that covers the 34 GHz-1.1 THz and the 20-900 cm^-1 ranges. The analysis was performed using the torsion-rotation Hamiltonian model based on the rho-axis method. We determined a model that describes the ground and first excited torsional states of CD_3OH, up to quantum numbers J ⩽ 55 and K_a ⩽ 23, and we derived a line list for radio-astronomical observations. This list is accurate up to at least 1.1 THz and should be sufficient for all types of radio-astronomical searches for this methanol isotopolog. It was used to search for CD_3OH in data from the Protostellar Interferometric Line Survey of IRAS 16293-2422 using ALMA. CD_3OH is securely detected in the data, with a large number of clearly separated and well-reproduced lines. We detected lines belonging to the ground and the first excited torsional states. The derived abundance of CD_3OH relative to non-deuterated isotopolog confirm the significant enhancement of this multiply deuterated variant. This finding is in line with other observations of multiply deuterated complex organic molecules and may serve as an important constraint on their formation models.

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 nu(2), 2 nu(4) and combinational nu(2) +nu(4) bands are located. A line strength analysis of the 2018 (1636/211/171) experimentally recorded transitions of the (SiH4)-Si-28, (SiH4)-Si-29, and (SiH4)-Si-30 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 (SiH4)-Si-28, (SiH4)-Si-29 and (SiH4)-Si-30 species, respectively) were obtained from the weighted fit which reproduce initial experimental line strengths of (SiH4)-Si-28, (29) SiH4 and (SiH4)-Si-30 with the d rms = 3.65%, 3.77% and 3.46%. Self-broadening coefficients of 1064 lines (typically lying between (8 and 10)x10(-2) cm(-1) . atm(-1)) and self-shift coefficients of 785 lines (typically lying between (5 and 10) x10-3 cm(-1).atm(-1)) of all three isotopologues of silane were determined from the multi-spectrum analysis of these lines. (C) 2021 Elsevier Ltd. All rights reserved.

High-resolution infrared spectra of the D2S molecule were experimentally recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and theoretically analyzed in the region of 700 - 1800 cm(-1), where the nu(2) and 2 nu(2) bands are located. For the first time, transitions were assigned to the 2 nu(2) and 2 nu(2) - nu(2) bands of the (D2S)-S-32 and (D2S)-S-34 isotopologues. For the ground vibrational state and the nu(2) band of (D2S)-S-34, the spectral information was considerably extended in comparison with preceding works. For the first time, transitions belonging to the rare (D2S)-S-33 hydrogen sulfide species were assigned to the nu(2) and 2 nu(2) bands, as well as a rotational structure of the ground vibrational state of (D2S)-S-33 was determined on the basis of experimental values of the ground state combination differences (maximum values of quantum numbers for used ground state combination differences were J(max) = 19, K-a(max) = 8, Delta J(max) = 2, Delta K-a(max) = 2). Sets of spectroscopic parameters of the Watson hamiltonian in A-reduction and Ir-representation was determined for the (010) and (020) vibrational states of all three discussed species and for the ground vibrational states of (D2S)-S-34 and (D2S)-S-33 from the weighted fit of parameters of this hamiltonian. The d rms of reproduction of the initial experimental data for all nine vibrational states (three vibrational states for any species) is not far from 1 x 10(-4) cm(-1) which is close to experimental errors in line positions. (C) 2020 Elsevier Ltd. All rights reserved.

The dynamics of photodissociation of PCl3 at 235 nm has been studied by monitoring of ground state Cl(2P3/2) and spin-orbitally excited Cl(2P1/2) atoms by REMPI technique. Also, the P+, PCl+, PCl+, and PCl+ photoions have been monitored non-resonantly in parallel with detection of REMPI-produced Cl+ ions. The speed distributions and speed-dependent anisotropy ± parameters β for all these particles have been determined by three-dimensional photofragment ion imaging technique. The β parameters are close to zero for all these particles. The relative yields of excited Cl(2P1/2) atoms for photodissociation of PCl3 is 0.49 0.03. The speed distributions of Cl(2P3/2) and Cl(2P1/2) atoms are bimodal. We explain the bimodal distributions as a result of competition between two REMPI channels. One channel is far-from-resonance one-photon photodissociation, the another channel is near-resonant two-photon ionisation followed by near-resonance one-photon photodissociation.

The strengths of 176 transitions of the 5 nu(2) band of (H2S)-S-32 were experimentally recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and theoretically analyzed. The seven effective dipole moment parameters of this band were obtained from the weighted fit which reproduce the initial experimental line strengths with the d(rms) = 3.4%. A comparison of the obtained results with the results of variational calculation and HITRAN data is presented. (C) 2019 Elsevier Ltd. All rights reserved.