The microwave spectra of NSF<sub>3</sub> in vibrationally excited states

Small, C.E.; Smith, J.

doi:10.1080/00268977900103101

Cited by 10 publications

(16 citation statements)

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“…[22] and the structure of Ref. [29], it has been calculated that the magnitude of c N (1) for NSF 3 is 0.13 kHz, a value which is much smaller than that determined here, as can be seen from Table VI. It seems that for this molecule, c E (1) does not vanish, but rather is dominant, as is typically the case for the diagonal elements c αα .…”

Section: A the Fluorine Spin-rotation Constantscontrasting

confidence: 64%

“…The other 14 N coupling mechanisms do not make significant contributions to the spectrum. For the classical dipole-dipole interaction between I N and the total fluorine spin I T , the coupling constant can be calculated from the associated nuclear g factors [1] and the molecular structure [29]. The resulting energy shifts are negligible.…”

Section: Splitting Patterns For the Nitrogen Quadrupole Interactionmentioning

confidence: 99%

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Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

et al. 2010

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For the principal isotopologue 14 N 32 S 19 F 3 of thiazyl trifluoride in the degenerate fundamental state (v 5 = 1), the hyperfine structure has been investigated in the Q-branch spectrum between 8 and 26.5 GHz using microwave Fourier transform waveguide spectrometers with a resolution limit of ≈30 kHz. In addition to l-type doubling spectra and l-type resonance transitions with ( k = l = ±2), perturbation-allowed spectra were measured with (k − l) = ±3, ±6. The range in J was from 13 to 61; for the lower states, kl = −3, −2, −1, 0, +1. For all the transitions, the hyperfine patterns observed are predicted to be doublets when only the nitrogen quadrupole Hamiltonian H N Q is taken into account. Doublets were indeed measured for transitions with RV = A 1 ↔ A 2 , where RV is the rovibrational symmetry. However, when RV = E ↔ E, triplets and quartets were observed in addition to doublets. These anomalous hyperfine patterns are shown to be due to the ( k = ±1) and ( k = ±2) matrix elements of the fluorine spin-rotation Hamiltonian H F SR characterized by the fluorine spin-rotation constants c(1) = 1 2 (c xz + c * zx ) and c(2) = 1 2 (c xx − c yy ), respectively. These terms in H F SR lift the parity degeneracy for RV = E. The rovibrational Hamiltonian H RV was adopted from an earlier partner study [S. Macholl et al., J. Phys. Chem. A 113, 668 (2009)]. A good fit to the hyperfine data was obtained with a standard deviation of 3.1 kHz. In the fitting process, 12 rovibrational parameters were varied, while the remaining constants in H RV were left at the values of Macholl et al. In addition, six hyperfine parameters were determined: four in H N Q , and two in H F SR . It was found that |c(1)| = 7.48(24) kHz and |c(2)| = 2.423 (22) kHz. This determination of c(1) is the first to be reported based on frequency measurements. In all the previous detections of parity doubling where the splittings were accounted for quantitatively, the levels involved had K = |k| = 1 in studies of the ground vibrational state or G ≡ |k − l| = 1 in investigations of degenerate vibrational states. In the current work, several different values of G were involved, thus demonstrating experimentally for the first time that this splitting process is a general phenomenon. The key to the observation of the parity doubling lies in the regional resonances discovered by Macholl et al. The clustering of rovibrational levels at low K leads to severe mixing. For each eigenstate involved in a regional resonance, the eigenstate consists of a linear superposition of basis vectors with several different values of kl having sizable expansion coefficients. As a result, the ( k = ±1, ±2) matrix elements of H F SR that typically connect levels widely separated in energy occur here effectively on the diagonal, thereby greatly enhancing the effects of c(1) and c(2). These spin-rotation matrix elements are derived here for RV = E in the low-field representation.

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Section: A the Fluorine Spin-rotation Constantscontrasting

confidence: 64%

Section: Splitting Patterns For the Nitrogen Quadrupole Interactionmentioning

confidence: 99%

Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

et al. 2010

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“…All transition frequencies were reproduced to within their experimental errors. In both reductions, the standard deviation was 20.5 kHz for data measured in this work, and 29.7 kHz for data of Small and Smith . The values of the parameters obtained for each reduction are given in Table .…”

Section: Multiple Fitting Analysismentioning

confidence: 86%

“…For v 6 = 1, | q 22 | is not large (≈0.25 MHz), but | A − B − Aζ | is relatively small (≈813 MHz). Furthermore, both states are well populated at room temperature …”

Section: Spectramentioning

confidence: 97%

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Rotational Spectrum of NSF₃ in the Ground and v₅ = 1 Vibrational States: Observation of Q-Branch Perturbation-Allowed Transitions with Δ(k − l) = 0, ±3, ±6 and Anomalies in the Rovibrational Structure of the v₅ = 1 State

et al. 2009

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The rotational spectrum of NSF3 in the ground and v5 = 1 vibrational states has been investigated in the centimeter- and millimeter-wave ranges. R-branch (J + 1 <-- J) transitions for J = 0, 1 and Q-branch rotational transitions for the v5 = 1 vibrational state have been measured by waveguide Fourier transform microwave spectroscopy in the range 8-26.5 GHz. The Q-branch transitions include 28 direct l-type doubling transitions (kl = +1, A1) <--> (kl = +1, A2) with J < or = 62, and 108 direct l-type resonance transitions following the selection rule delta k = delta l = +/-2 with J < or = 60 and G = |k - l| < or = 3. A process called "regional resonance" was observed in which a cluster of levels interacted strongly over a large range in J. This process led to the observation of 55 perturbation-allowed transitions following the selection rules delta(k - l) = +/-3, +/-6. In particular, (kl = +1, A+) <--> (kl = -2, A-), (kl = +4, A+) <--> (kl = +1, A-), (kl = +2) <--> (kl = -1), (kl = +3) <--> (kl = 0), (kl = +2) <--> (kl = -3), and (kl = +3) <--> (kl = -3). The various aspects of the regional resonances are discussed in detail. An accidental near-degeneracy of the kl = 0 and kl = -4 levels at J = 26/27 led to the observation of perturbation-allowed transitions following the selection rule delta(k-l) = +/-6 with (kl = +2) <--> (kl = -4). A corresponding near-degeneracy between kl = -1 and kl = -3 levels at J = 30/31 led to the detection of similar transitions, but with (kl = +3) <--> (kl = -3). In the range 230-480 GHz, R-branch rotational transitions have been measured by absorption spectroscopy up to J = 49 in the ground-state and up to J = 50 in the v5 = 1 vibrational state. The transition frequencies have been analyzed using various reduced forms of the effective Hamiltonians. The data for the v5 = 1 vibrational state have been fitted successfully using two models up to seventh order with delta k = +/-3 interaction parameters constrained (dt constrained to zero, and epsilon to zero or to the ground-state value). On the other hand, reductions with the (delta k = +/-1, deltal = -/+2) interaction parameter q12 fixed to zero failed to reproduce the experimental data since the parameters defining the reduction transformation do not arise in the correct order of magnitude. The ground-state data have been analyzed including parameters up to fourth order constraining either parameters of the delta k = +/-3 interactions to zero (reduction A), or of the delta k = +/-6 interactions to zero (reduction B). The unitary equivalence of the different parameter sets obtained is demonstrated for both vibrational states.

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Substance No. 19 - 43

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Landolt-Börnstein - Group II Molecules and Radicals

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The microwave spectra of NSF₃ in vibrationally excited states

Cited by 10 publications

References 13 publications

Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

Rotational Spectrum of NSF₃ in the Ground and v₅ = 1 Vibrational States: Observation of Q-Branch Perturbation-Allowed Transitions with Δ(k − l) = 0, ±3, ±6 and Anomalies in the Rovibrational Structure of the v₅ = 1 State

Substance No. 19 - 43

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The microwave spectra of NSF3 in vibrationally excited states

Cited by 10 publications

References 13 publications

Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

Anomalous hyperfine structure of NSF3in the degenerate vibrational statev5=1: Lifting of the parity degeneracy by the

Rotational Spectrum of NSF3 in the Ground and v5 = 1 Vibrational States: Observation of Q-Branch Perturbation-Allowed Transitions with Δ(k − l) = 0, ±3, ±6 and Anomalies in the Rovibrational Structure of the v5 = 1 State

Substance No. 19 - 43

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The microwave spectra of NSF₃ in vibrationally excited states

Rotational Spectrum of NSF₃ in the Ground and v₅ = 1 Vibrational States: Observation of Q-Branch Perturbation-Allowed Transitions with Δ(k − l) = 0, ±3, ±6 and Anomalies in the Rovibrational Structure of the v₅ = 1 State