Structure and dipole moment of trans propargyl amine by microwave spectroscopy

Cervellati, Rinaldo; Camináti, Walther; Esposti, C. Degli; Mirri, A.M.

doi:10.1016/0022-2852(77)90297-1

Cited by 20 publications

(23 citation statements)

References 7 publications

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“…Although the aim of this study is to provide accurate rest frequencies for the most stable conformer of propargylamine, that is, the trans form, a computational investigation of the molecular structure and dipole moment for the gauche conformer was also carried out at the B2PLYP-D3BJ/aug-cc-pVTZ level, mainly to check the reliability of the conclusions drawn by Cervellati et al (1977) about the energy of the undetected gauche form. The following values of the dipole moment components of the two isomers were obtained at the same level of theory: µ a = 0.5215 D and µ b = 0.4351 D for the trans form, and µ a = 0.7334 D, µ b = 0.7265 D, and µ c = 1.0480 D for the gauche form.…”

Section: Computationsmentioning

confidence: 99%

“…Trans-propargylamine is a near-prolate asymmetric-top molecule (κ = −0.966) of C s symmetry, with non-zero dipole moment components along the a and b principal axes that define the symmetry plane of the molecule (Cervellati et al 1977). Regarding the vibrational ground state, initial A&A 615, A176 (2018) assignments in the mm-wave region were guided by the spectroscopic constants available from the previous cm-wave investigation (Cervellati et al 1977). a R-branch transitions and additional b-type lines were first recorded in the 100 GHz region.…”

Section: Ground Statementioning

confidence: 99%

“…For the present FTMW measurements, we adopted a conservative value of σ i = 5 kHz to take into account the asymmetric line broadening produced by the blending of hyperfine components due to the nuclear spins of the five hydrogen atoms. The previous Stark-modulation measurements (Cervellati et al 1977) were given with an average uncertainty of σ i = 85 kHz.…”

Section: Ground Statementioning

confidence: 99%

“…Rotational lines of trans-propargylamine (C s symmetry group) were first observed by Bolton et al (1968). A subsequent study in the 8-40 GHz frequency range (Cervellati et al 1977) allowed the determination of the rotational constants of nine isotopically substituted species, from which a reliable molecular structure could be calculated. Additionally, the dipole moment of trans-propargylamine was determined by Stark effect measurements (the values µ a = 0.586 D and µ b = 0.445 D being derived), but the very limited frequency range over which the rotational spectrum was studied prevented from obtaining very accurate values of the centrifugal distortion constants.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the dipole moment of trans-propargylamine was determined by Stark effect measurements (the values µ a = 0.586 D and µ b = 0.445 D being derived), but the very limited frequency range over which the rotational spectrum was studied prevented from obtaining very accurate values of the centrifugal distortion constants. Although Cervellati et al (1977) were able to observe rotational lines of the 13 C and 15 N containing species in natural abundance, the search for transitions of the gauche conformer was unsuccessful. This non-detection, combined with a theoretical evaluation of the dipole moment components of the gauche form, made it possible to estimate a lower limit of approximately 2600 cal mol −1 (corresponding to 910 cm −1 ) for the energy difference between the gauche and the trans forms.…”

Section: Introductionmentioning

confidence: 99%

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Accurate rest frequencies for propargylamine in the ground and low-lying vibrational states

Esposti

Dore

Puzzarini

et al. 2018

A&A

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Context. To date, several complex organic molecules have been detected in the interstellar medium, and they have been suggested as precursors of biologically important species. Propargylamine (HC ≡C−CH2−NH2) is structurally similar to a number of other organic molecules which have already been identified by radioastronomy, making it a good candidate for astrophysical detection. Aims. This work provides accurate rest frequencies of propargylamine, from the centimeter-wave to the submillimeter-wave region, useful to facilitate the detection of this molecule in the interstellar medium. Methods. An extensive laboratory study of the rotational spectrum of propargylamine has been performed using a pulsed-jet Fourier Transform Microwave (FTMW) spectrometer (7–19 GHz frequency range) and a frequency modulation microwave spectrometer (75–560 GHz). Several hundred rotational transitions of propargylamine were recorded in the ground and three lowest excited vibrational states. The experiments were supported by high-level ab initio computations, mainly employed to characterize the vibrational state structure and to predict spectroscopic parameters unknown prior to this study. Results. The measured transition frequencies yielded accurate rotational constants and the complete sets of quartic and sextic centrifugal distortion constants for propargylamine in its vibrational ground state. 14N-nuclear quadrupole coupling constants were also determined. Rotational and quartic centrifugal distortion constants were also obtained for the low-lying excited states v13 = 1 (A′), v20 = 1 (A″), and v21 = 1 (A″). The a-type Coriolis resonance which couples the v13 = 1 and v21 = 1 levels was analyzed. Conclusions. The determined spectroscopic constants allowed for the compilation of a dataset of highly accurate rest frequencies for astrophysical purposes in the millimeter and submillimeter regions with 1σ uncertainties that are smaller than 0.050 MHz, corresponding to 0.03 km s−1 at 500 GHz in radial equivalent velocity.

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Section: Computationsmentioning

confidence: 99%

Section: Ground Statementioning

confidence: 99%

Section: Ground Statementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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