Luca Dore - Academia.edu (original) (raw)
Papers by Luca Dore
AIP Conference Proceedings, 1997
Self-broadening and self-shifting of methyl fluoride, 12CH3F, have been investigated in the 50-40... more Self-broadening and self-shifting of methyl fluoride, 12CH3F, have been investigated in the 50-408 GHz range for the rotational transitions J=0-->1, J=1-->2, J=2-->3, J=5-->6, and J=7-->8 and for their DeltaMJ=0 and DeltaMJ=+/-1 Stark components, as they were well resolved by an appropriate electric field. The experimental MJ-dependence of the collisional relaxation parameters is in very good agreement with the theoretical one,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2015
Diacetylene (HC 4 H) is the simplest polyyne and has been the subject of several studies related ... more Diacetylene (HC 4 H) is the simplest polyyne and has been the subject of several studies related to technology, materials, supramolecular chemistry, non-linear optics. It has been detected in space and in the atmosphere of Titan. Moreover, it is a model species to test sophisticated ab initio calculations. In this paper we report the study of the infrared spectrum of the rare isotopologue DC 4 D below 1000 cm À 1. The experiment has been performed by high resolution Fourier transform infrared spectroscopy. The ν 8 fundamental band, the ν 6 þ ν 9 , ν 7 þ ν 8 , and ν 6 þ ν 8 combination bands and the ν 8 þ ν 9 À ν 9 hot band have been observed and analysed, providing a set of accurate spectroscopic parameters. A global fit has also been performed in order to take into account the anharmonic resonance between the v 3 ¼ 1 and the v 8 ¼ v 9 ¼ 1 states. The final results obtained from the global fit show a good improvement in the spectroscopic parameters for both the upper and lower states.
Molecular Physics, 2010
Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono-and... more Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono-and bideuterated-water containing 17 O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spinrotation and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimentally determined 17 O spinrotation constants of D 2 17 O and HD 17 O were used to derive the paramagnetic part of the corresponding nuclear magnetic shielding constants. Together with the computed diamagnetic contributions as well as the vibrational and temperature corrections, the latter constants have been employed to confirm the oxygen nuclear magnetic shielding scale, recently established on the basis of spin-rotation data for H 2 17 O
The Astrophysical Journal, 2002
The maps presented in Paper I are here used to infer the variation of the column densities of HCO... more The maps presented in Paper I are here used to infer the variation of the column densities of HCO + , DCO + , N 2 H + , and N 2 D + as a function of distance from the dust peak. These results are interpreted with the aid of a crude chemical model which predicts the abundances of these species as a function of radius in a spherically symmetric model with radial density distribution inferred from the observations of dust emission at millimeter wavelengths and dust absorption in the infrared. Our main observational finding is that the N (N 2 D +)/N (N 2 H +) column density ratio is of order 0.2 towards the L1544 dust peak as compared to N (DCO +)/N (HCO +) = 0.04. We conclude that this result as well as the general finding that N 2 H + and N 2 D + correlate well with the dust is caused by CO being depleted to a much higher degree than molecular nitrogen in the high density core of L1544. Depletion also favors deuterium enhancement and thus N 2 D + , which traces the dense and highly CO-depleted core nucleus, is much more enhanced than DCO +. Our models do not uniquely define the chemistry in the high density depleted nucleus of L1544 but they do suggest that the ionization degree is a few times 10 −9 and that the ambipolar diffusion time scale is locally similar to the free fall time. It seems likely that the lower limit which one obtains to ionization degree by summing all observable molecular ions is not a
Physical Review A, 1994
We present a theoretical model for studying the shape of the rotational lines of molecular ions p... more We present a theoretical model for studying the shape of the rotational lines of molecular ions perturbed by collisions with neutral species. This model shows that the interaction between the ionic monopole and the multipole moments of the perturber has no role in the collisional relaxation of the lines. The eHect of the ionic monopole is restricted to that of inducing a polarization of the neutral perturbers that can cause relaxation by interaction with the other permanent moments of the absorbing ion. We also present, for HCO+ perturbed by argon, an experimental study of the pressure broadening and shift of the rotational lines J = 1 E-0, 2 +-1, and 4 +-3. The agreement between theory and experiment is satisfactory.
Molecular Physics, 2011
The infrared spectrum of diacetylene has been recorded at high resolution between 500 and 1000 cm... more The infrared spectrum of diacetylene has been recorded at high resolution between 500 and 1000 cm −1 by Fourier transform spectroscopy. More than 1200 transitions were assigned to 5 bands: the ν 8 fundamental, the ν 7 + ν 9 combination, and the ν 3 − ν 9 difference bands as well as the most intense ν 8 + ν 9 − ν 9 and ν 7 + 2ν 9 − ν 9 hot bands. The data were analysed together with the previously recorded millimetre-wave lines for the ν 8 −ν 6 and ν 8 +ν 9 −(ν 6 +ν 9) difference bands. Rotational and vibrational l-type resonances, together with the cubic anharmonic interactions which couple the v 3 = 1 stretching state with the v 8 = v 9 = 1 combination and v 7 = 2 overtone states have been considered in the least-squares fits to the observed wavenumbers in order to derive reliable spectroscopic parameters. The spectral analyses deliver very precise B 0 and D 0 parameters and experimental values of the anharmonicity constants for the bending-bending combination states of diacetylene below 1000 cm −1 .
Molecular Physics, 2011
The deuterated radical ND was produced in a DC discharge cell cooled at liquid nitrogen temperatu... more The deuterated radical ND was produced in a DC discharge cell cooled at liquid nitrogen temperature. The discharge proved to be vibrationally hot, therefore the transient species could be detected in its vibrational excited states up to v = 6. By scanning in the 431-531 GHz frequency region, several fine-structure components of the N = 1 ← 0 transition in vibrational excited states were observed, each of them showing a complex hyperfine structure. A global analysis, including the measured frequencies and previous submillimeter-wave and infrared data, allowed an accurate determination of the equilibrium spectroscopic parameters of the ND radical including fine and hyperfine constants. A very precise determination of the equilibrium bond length re was obtained. This value is not consistent with the value reported in literature from NH data. This incongruity was discussed in terms of the breakdown of the Born-Oppenheimer approximation. In view of the recent detection of ND in a solar-mass protostar (A. Bacmann et al., Astron. Astrophys. 521, L42 (2010)), an extended spectroscopic characterization of this deuterated isotopologue of the NH species may prove useful, considering the large deuterium enhancement observed in molecular clouds.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2004
Because of their lower depleting effect on the ozone in the atmosphere, there has been much recen... more Because of their lower depleting effect on the ozone in the atmosphere, there has been much recent interest in the fluorinated hydrocarbons as replacements for chlorofluorocarbons and hydrochlorofluorocarbons.Since data on the broadening of rotational lines are required for quantitative monitoring of trace compounds in the atmosphere (especially broadening by collision with N2 and O2), self- and pressure-broadening of rotational transitions
Journal of Molecular Spectroscopy, 2000
The nuclear quadrupole hyperfine structure in rotational transitions of cis-1-chloro-2-fluoroethy... more The nuclear quadrupole hyperfine structure in rotational transitions of cis-1-chloro-2-fluoroethylene was measured for both (35)Cl and (37)Cl containing isotopomers in the millimeter-wave region. Near degeneracies of the 9(3,7) and 10(2,9) levels of (35)ClHC&dbond;CFH and of the 19(9,10/11) and 17(10,7/8) levels of (37)ClHC&dbond;CFH cause strong perturbations of the hyperfine patterns and give rise to perturbation-allowed DeltaJ = 2 and DeltaJ = 3 transitions. Lamb-dip measurements of such perturbed hyperfine patterns and of forbidden DeltaJ = +2 and perturbation-enhanced DeltaJ = 0 transitions of (35)ClHC&dbond;CFH provided an accurate determination of chi(ab), the off-diagonal element of the inertial nuclear quadrupole tensor. For (37)ClHC&dbond;CFH, chi(ab) was determined for the first time thanks to the observation of perturbed hyperfine patterns and of forbidden DeltaJ = +3 and DeltaJ = -2 transitions. Additional measurements of hyperfine structures led to improved values for the diagonal elements of the chi tensor of both (35)Cl and (37)Cl. Moreover, the complete inertial nuclear quadrupole tensor was evaluated from the field gradient at the chlorine nucleus computed by using the Multi-Configuration Self-Consistent Field (MCSCF) approach and employing basis sets of triple-zeta quality: very good agreement with the experiment was obtained. Copyright 2000 Academic Press.
Journal of Molecular Spectroscopy, 1995
ABSTRACT
Journal of Molecular Spectroscopy, 1995
ABSTRACT
Journal of Molecular Spectroscopy, 1998
Copyright
Journal of Molecular Spectroscopy, 2010
The hyperfine structure in the ground-state rotational spectrum of methanimine was studied in the... more The hyperfine structure in the ground-state rotational spectrum of methanimine was studied in the frequency range of 64-172 GHz by means of the Lamb-dip technique. This allowed to resolve, in some hyperfine components due to the 14 N nucleus, doublets separated by only some tenth of kHz. We explain the splittings as due to magnetic interactions of the three protons with their molecular environment. The analysis of the experimental spectrum has been guided by quantum-chemical calculations of the hyperfine parameters.
Journal of Molecular Spectroscopy, 2006
The asymmetric species SHD 2 þ , produced in a magnetically confined negative glow discharge, was... more The asymmetric species SHD 2 þ , produced in a magnetically confined negative glow discharge, was spectroscopically observed for the first time by measuring its pure rotational spectrum by means of a submillimeter-wave source-modulated spectrometer. In addition, the J = 2 ‹ 1 to 4 ‹ 3 transitions of SD 3 þ and 34 SD 3 þ , and the J = 1 ‹ 0 and 2 ‹ 1 lines of SH 3 þ and 34 SH 3 þ were measured in the 290-654 GHz frequency region. All the determined rotational constants allowed to calculate the molecular structure of the sulfonium ion at various levels of description of the contribution of zero-point vibrations. The r m method of Watson et al. [
Journal of Molecular Spectroscopy, 1986
Journal of Molecular Spectroscopy, 2003
The pure rotational spectrum of 13 C 17 O has been observed in the millimeter-and submillimeter-w... more The pure rotational spectrum of 13 C 17 O has been observed in the millimeter-and submillimeter-wave region using the Lamb-dip technique in order to increase the instrumental resolving power and so to resolve both the hyperfine structure due to 17 O and that due to 13 C. In this way very accurate values of the rotational and centrifugal distortion constants, the 17 O nuclear electric quadrupole coupling constant and the 17 O and 13 C spin-rotation constants have been obtained. In addition, the J ¼ 1 0 and J ¼ 2 1 transitions of 13 C 18 O have been recorded using the Lamb-dip technique. The resolved hyperfine structure of these transitions allowed us to determine the rotational and 13 C spin-rotation constants. The experimental determination of all these parameters has been supported by ab initio computations.
The Journal of Chemical Physics, 2003
Rotational transitions of DCO+ in vibrationally excited states were measured in the region 360–44... more Rotational transitions of DCO+ in vibrationally excited states were measured in the region 360–440 GHz. The states investigated are: 0 2 0 (with l=0,2), 0 3 0 (with l=1,3), 0 4 0 (with l=0,2,4), 0 11 1, and 1 00 0. This study allowed us to carefully analyze the vibrational interaction affecting the first C–D stretching state 1 00 0, which was confirmed to be due to the 0 11 1 state. Taking account of the perturbation effect on the rotational constants of the involved states allowed to derive an accurate equilibrium structure of HCO+, which resulted to be rCH=1.092 04 Å and rCO=1.105 58 Å.
ChemPhysChem, 2006
An experimental and theoretical study of the pressure broadening and the pressure shift of three ... more An experimental and theoretical study of the pressure broadening and the pressure shift of three HCO(+) rotational lines (j=4<--3, 5<--4 and 6<--5) perturbed by collisions with Ar is presented. The measurements are carried out at 77 K and are compared to close-coupling calculations performed on an accurate potential energy surface for the Ar-HCO(+) interaction extending from small to very large separations between the ion and the perturber. For the pressure broadening, agreement between experiment and theory is satisfactory for both close-coupling and semiclassical calculations. For the pressure shift, however, close-coupling calculations are superior. The results agree with experiment in sign and order of magnitude, while semiclassical calculations are inaccurate for the shift of the presently studied lines because they neglect the contribution of strong collisions.
Chemical Physics Letters, 1996
The rotational spectrum of DCO + in the 01tl, 03t0 and 0400 vibrational excited states has been s... more The rotational spectrum of DCO + in the 01tl, 03t0 and 0400 vibrational excited states has been studied to derive the rotational, centrifugal distortion and /-type doubling constants. It has been found that there is a Coriolis-type interaction involving the 01tl and 10°0 states, thus ruling out a previous hypothesis suggesting the existence of a Fermi resonance between the 10°0 and 04o0 states.
Chemical Physics Letters, 1995
... [10]. Protonated formaldehyde was first spectroscopically identified by Amano and Warner [11]... more ... [10]. Protonated formaldehyde was first spectroscopically identified by Amano and Warner [11] by observing the vl fundamental band at 2.9 Ixm. ... Rev. Letters 21 (1968) 1701. [3] LE Snyder, D. Buhl, B. Zuckerman and P. Palmer, Phys. Rev. Letters 22 (1969) 679. ...
AIP Conference Proceedings, 1997
Self-broadening and self-shifting of methyl fluoride, 12CH3F, have been investigated in the 50-40... more Self-broadening and self-shifting of methyl fluoride, 12CH3F, have been investigated in the 50-408 GHz range for the rotational transitions J=0-->1, J=1-->2, J=2-->3, J=5-->6, and J=7-->8 and for their DeltaMJ=0 and DeltaMJ=+/-1 Stark components, as they were well resolved by an appropriate electric field. The experimental MJ-dependence of the collisional relaxation parameters is in very good agreement with the theoretical one,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2015
Diacetylene (HC 4 H) is the simplest polyyne and has been the subject of several studies related ... more Diacetylene (HC 4 H) is the simplest polyyne and has been the subject of several studies related to technology, materials, supramolecular chemistry, non-linear optics. It has been detected in space and in the atmosphere of Titan. Moreover, it is a model species to test sophisticated ab initio calculations. In this paper we report the study of the infrared spectrum of the rare isotopologue DC 4 D below 1000 cm À 1. The experiment has been performed by high resolution Fourier transform infrared spectroscopy. The ν 8 fundamental band, the ν 6 þ ν 9 , ν 7 þ ν 8 , and ν 6 þ ν 8 combination bands and the ν 8 þ ν 9 À ν 9 hot band have been observed and analysed, providing a set of accurate spectroscopic parameters. A global fit has also been performed in order to take into account the anharmonic resonance between the v 3 ¼ 1 and the v 8 ¼ v 9 ¼ 1 states. The final results obtained from the global fit show a good improvement in the spectroscopic parameters for both the upper and lower states.
Molecular Physics, 2010
Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono-and... more Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono-and bideuterated-water containing 17 O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spinrotation and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimentally determined 17 O spinrotation constants of D 2 17 O and HD 17 O were used to derive the paramagnetic part of the corresponding nuclear magnetic shielding constants. Together with the computed diamagnetic contributions as well as the vibrational and temperature corrections, the latter constants have been employed to confirm the oxygen nuclear magnetic shielding scale, recently established on the basis of spin-rotation data for H 2 17 O
The Astrophysical Journal, 2002
The maps presented in Paper I are here used to infer the variation of the column densities of HCO... more The maps presented in Paper I are here used to infer the variation of the column densities of HCO + , DCO + , N 2 H + , and N 2 D + as a function of distance from the dust peak. These results are interpreted with the aid of a crude chemical model which predicts the abundances of these species as a function of radius in a spherically symmetric model with radial density distribution inferred from the observations of dust emission at millimeter wavelengths and dust absorption in the infrared. Our main observational finding is that the N (N 2 D +)/N (N 2 H +) column density ratio is of order 0.2 towards the L1544 dust peak as compared to N (DCO +)/N (HCO +) = 0.04. We conclude that this result as well as the general finding that N 2 H + and N 2 D + correlate well with the dust is caused by CO being depleted to a much higher degree than molecular nitrogen in the high density core of L1544. Depletion also favors deuterium enhancement and thus N 2 D + , which traces the dense and highly CO-depleted core nucleus, is much more enhanced than DCO +. Our models do not uniquely define the chemistry in the high density depleted nucleus of L1544 but they do suggest that the ionization degree is a few times 10 −9 and that the ambipolar diffusion time scale is locally similar to the free fall time. It seems likely that the lower limit which one obtains to ionization degree by summing all observable molecular ions is not a
Physical Review A, 1994
We present a theoretical model for studying the shape of the rotational lines of molecular ions p... more We present a theoretical model for studying the shape of the rotational lines of molecular ions perturbed by collisions with neutral species. This model shows that the interaction between the ionic monopole and the multipole moments of the perturber has no role in the collisional relaxation of the lines. The eHect of the ionic monopole is restricted to that of inducing a polarization of the neutral perturbers that can cause relaxation by interaction with the other permanent moments of the absorbing ion. We also present, for HCO+ perturbed by argon, an experimental study of the pressure broadening and shift of the rotational lines J = 1 E-0, 2 +-1, and 4 +-3. The agreement between theory and experiment is satisfactory.
Molecular Physics, 2011
The infrared spectrum of diacetylene has been recorded at high resolution between 500 and 1000 cm... more The infrared spectrum of diacetylene has been recorded at high resolution between 500 and 1000 cm −1 by Fourier transform spectroscopy. More than 1200 transitions were assigned to 5 bands: the ν 8 fundamental, the ν 7 + ν 9 combination, and the ν 3 − ν 9 difference bands as well as the most intense ν 8 + ν 9 − ν 9 and ν 7 + 2ν 9 − ν 9 hot bands. The data were analysed together with the previously recorded millimetre-wave lines for the ν 8 −ν 6 and ν 8 +ν 9 −(ν 6 +ν 9) difference bands. Rotational and vibrational l-type resonances, together with the cubic anharmonic interactions which couple the v 3 = 1 stretching state with the v 8 = v 9 = 1 combination and v 7 = 2 overtone states have been considered in the least-squares fits to the observed wavenumbers in order to derive reliable spectroscopic parameters. The spectral analyses deliver very precise B 0 and D 0 parameters and experimental values of the anharmonicity constants for the bending-bending combination states of diacetylene below 1000 cm −1 .
Molecular Physics, 2011
The deuterated radical ND was produced in a DC discharge cell cooled at liquid nitrogen temperatu... more The deuterated radical ND was produced in a DC discharge cell cooled at liquid nitrogen temperature. The discharge proved to be vibrationally hot, therefore the transient species could be detected in its vibrational excited states up to v = 6. By scanning in the 431-531 GHz frequency region, several fine-structure components of the N = 1 ← 0 transition in vibrational excited states were observed, each of them showing a complex hyperfine structure. A global analysis, including the measured frequencies and previous submillimeter-wave and infrared data, allowed an accurate determination of the equilibrium spectroscopic parameters of the ND radical including fine and hyperfine constants. A very precise determination of the equilibrium bond length re was obtained. This value is not consistent with the value reported in literature from NH data. This incongruity was discussed in terms of the breakdown of the Born-Oppenheimer approximation. In view of the recent detection of ND in a solar-mass protostar (A. Bacmann et al., Astron. Astrophys. 521, L42 (2010)), an extended spectroscopic characterization of this deuterated isotopologue of the NH species may prove useful, considering the large deuterium enhancement observed in molecular clouds.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2004
Because of their lower depleting effect on the ozone in the atmosphere, there has been much recen... more Because of their lower depleting effect on the ozone in the atmosphere, there has been much recent interest in the fluorinated hydrocarbons as replacements for chlorofluorocarbons and hydrochlorofluorocarbons.Since data on the broadening of rotational lines are required for quantitative monitoring of trace compounds in the atmosphere (especially broadening by collision with N2 and O2), self- and pressure-broadening of rotational transitions
Journal of Molecular Spectroscopy, 2000
The nuclear quadrupole hyperfine structure in rotational transitions of cis-1-chloro-2-fluoroethy... more The nuclear quadrupole hyperfine structure in rotational transitions of cis-1-chloro-2-fluoroethylene was measured for both (35)Cl and (37)Cl containing isotopomers in the millimeter-wave region. Near degeneracies of the 9(3,7) and 10(2,9) levels of (35)ClHC&dbond;CFH and of the 19(9,10/11) and 17(10,7/8) levels of (37)ClHC&dbond;CFH cause strong perturbations of the hyperfine patterns and give rise to perturbation-allowed DeltaJ = 2 and DeltaJ = 3 transitions. Lamb-dip measurements of such perturbed hyperfine patterns and of forbidden DeltaJ = +2 and perturbation-enhanced DeltaJ = 0 transitions of (35)ClHC&dbond;CFH provided an accurate determination of chi(ab), the off-diagonal element of the inertial nuclear quadrupole tensor. For (37)ClHC&dbond;CFH, chi(ab) was determined for the first time thanks to the observation of perturbed hyperfine patterns and of forbidden DeltaJ = +3 and DeltaJ = -2 transitions. Additional measurements of hyperfine structures led to improved values for the diagonal elements of the chi tensor of both (35)Cl and (37)Cl. Moreover, the complete inertial nuclear quadrupole tensor was evaluated from the field gradient at the chlorine nucleus computed by using the Multi-Configuration Self-Consistent Field (MCSCF) approach and employing basis sets of triple-zeta quality: very good agreement with the experiment was obtained. Copyright 2000 Academic Press.
Journal of Molecular Spectroscopy, 1995
ABSTRACT
Journal of Molecular Spectroscopy, 1995
ABSTRACT
Journal of Molecular Spectroscopy, 1998
Copyright
Journal of Molecular Spectroscopy, 2010
The hyperfine structure in the ground-state rotational spectrum of methanimine was studied in the... more The hyperfine structure in the ground-state rotational spectrum of methanimine was studied in the frequency range of 64-172 GHz by means of the Lamb-dip technique. This allowed to resolve, in some hyperfine components due to the 14 N nucleus, doublets separated by only some tenth of kHz. We explain the splittings as due to magnetic interactions of the three protons with their molecular environment. The analysis of the experimental spectrum has been guided by quantum-chemical calculations of the hyperfine parameters.
Journal of Molecular Spectroscopy, 2006
The asymmetric species SHD 2 þ , produced in a magnetically confined negative glow discharge, was... more The asymmetric species SHD 2 þ , produced in a magnetically confined negative glow discharge, was spectroscopically observed for the first time by measuring its pure rotational spectrum by means of a submillimeter-wave source-modulated spectrometer. In addition, the J = 2 ‹ 1 to 4 ‹ 3 transitions of SD 3 þ and 34 SD 3 þ , and the J = 1 ‹ 0 and 2 ‹ 1 lines of SH 3 þ and 34 SH 3 þ were measured in the 290-654 GHz frequency region. All the determined rotational constants allowed to calculate the molecular structure of the sulfonium ion at various levels of description of the contribution of zero-point vibrations. The r m method of Watson et al. [
Journal of Molecular Spectroscopy, 1986
Journal of Molecular Spectroscopy, 2003
The pure rotational spectrum of 13 C 17 O has been observed in the millimeter-and submillimeter-w... more The pure rotational spectrum of 13 C 17 O has been observed in the millimeter-and submillimeter-wave region using the Lamb-dip technique in order to increase the instrumental resolving power and so to resolve both the hyperfine structure due to 17 O and that due to 13 C. In this way very accurate values of the rotational and centrifugal distortion constants, the 17 O nuclear electric quadrupole coupling constant and the 17 O and 13 C spin-rotation constants have been obtained. In addition, the J ¼ 1 0 and J ¼ 2 1 transitions of 13 C 18 O have been recorded using the Lamb-dip technique. The resolved hyperfine structure of these transitions allowed us to determine the rotational and 13 C spin-rotation constants. The experimental determination of all these parameters has been supported by ab initio computations.
The Journal of Chemical Physics, 2003
Rotational transitions of DCO+ in vibrationally excited states were measured in the region 360–44... more Rotational transitions of DCO+ in vibrationally excited states were measured in the region 360–440 GHz. The states investigated are: 0 2 0 (with l=0,2), 0 3 0 (with l=1,3), 0 4 0 (with l=0,2,4), 0 11 1, and 1 00 0. This study allowed us to carefully analyze the vibrational interaction affecting the first C–D stretching state 1 00 0, which was confirmed to be due to the 0 11 1 state. Taking account of the perturbation effect on the rotational constants of the involved states allowed to derive an accurate equilibrium structure of HCO+, which resulted to be rCH=1.092 04 Å and rCO=1.105 58 Å.
ChemPhysChem, 2006
An experimental and theoretical study of the pressure broadening and the pressure shift of three ... more An experimental and theoretical study of the pressure broadening and the pressure shift of three HCO(+) rotational lines (j=4<--3, 5<--4 and 6<--5) perturbed by collisions with Ar is presented. The measurements are carried out at 77 K and are compared to close-coupling calculations performed on an accurate potential energy surface for the Ar-HCO(+) interaction extending from small to very large separations between the ion and the perturber. For the pressure broadening, agreement between experiment and theory is satisfactory for both close-coupling and semiclassical calculations. For the pressure shift, however, close-coupling calculations are superior. The results agree with experiment in sign and order of magnitude, while semiclassical calculations are inaccurate for the shift of the presently studied lines because they neglect the contribution of strong collisions.
Chemical Physics Letters, 1996
The rotational spectrum of DCO + in the 01tl, 03t0 and 0400 vibrational excited states has been s... more The rotational spectrum of DCO + in the 01tl, 03t0 and 0400 vibrational excited states has been studied to derive the rotational, centrifugal distortion and /-type doubling constants. It has been found that there is a Coriolis-type interaction involving the 01tl and 10°0 states, thus ruling out a previous hypothesis suggesting the existence of a Fermi resonance between the 10°0 and 04o0 states.
Chemical Physics Letters, 1995
... [10]. Protonated formaldehyde was first spectroscopically identified by Amano and Warner [11]... more ... [10]. Protonated formaldehyde was first spectroscopically identified by Amano and Warner [11] by observing the vl fundamental band at 2.9 Ixm. ... Rev. Letters 21 (1968) 1701. [3] LE Snyder, D. Buhl, B. Zuckerman and P. Palmer, Phys. Rev. Letters 22 (1969) 679. ...