Microwave Spectra of Deutero-Ammonias

Lyons, Harold A.; Rueger, L. J.; Nuckolls, R. G.; Kessler, Myer

doi:10.1103/physrev.81.630

Cited by 21 publications

(8 citation statements)

References 7 publications

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“…Experiments performed with N H 3 [4], N D 3 [5] and N T 3 [6] reveal the existence of this inversion line in various rotational and vibrational bands. The frequencyν of the inversion line has been measured as a function of the gas pressure P for N H 3 [7,8] and N D 3 [9].…”

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Interaction Induced Localization in a Gas of Pyramidal Molecules

2002

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We propose a model to describe a gas of pyramidal molecules interacting via dipole-dipole interactions. The interaction modifies the tunneling properties between the classical equilibrium configurations of the single molecule and, for sufficiently high pressure, the molecules become localized in these classical configurations. We explain quantitatively, without free parameters, the shift to zero-frequency of the inversion line observed upon increase of the pressure in a gas of ammonia or deuterated ammonia. For sufficiently high pressures, our model suggests the existence of a superselection rule for states of different chirality in substituted derivatives.PACS numbers: 03.65. Xp, 33.20.Bx, 73.43.Nq, 33.55.Ad The behavior of gases of pyramidal molecules, i.e. molecules of the kind XY 3 like ammonia N H 3 , has been the object of investigations since the early developments of quantum mechanics [1]. However, the behavior of these systems is still debated and some experimental facts remain essentially unexplained [2].For the single pyramidal molecule, owing to the great differences of characteristic energies and times, some adiabatic approximations hold. In particular, the onedimensional inversion motion of the nucleus X across the plane containing the three nuclei Y can be separated from the rotational and vibrational nuclear degrees of freedom. The form of the effective potential for this motion is a double well which is symmetric with respect to the inversion plane [3]. Due to tunneling across the finite potential barrier, the eigenstates are delocalized in the two minima of the potential and, for energies below the barrier height, are grouped in doublets, i.e. couples of states with a relative splitting in energy small in comparison with the distance from the rest of the spectrum. For the pyramidal molecules under consideration, the thermal energy k B T at room temperature is much smaller than the distance between the first and the second doublet so that the problem can be reduced to the study of a two-level system corresponding to the symmetric and anti-symmetric states of the first doublet.The existence of delocalized stationary states is clearly in disagreement with the usual chemical view which, relying upon classical theory, considers the molecules as objects with a well defined spatial structure. In particular, for the molecules under consideration the classical view predicts one of the two pyramidal configurations corresponding to the nucleus X localized in one of the wells of the inversion potential.The quantum prediction of stationary delocalized states implies the presence of a line in the absorption spectrum, the so called inversion line, at a frequencȳ ν = ∆E/h, where ∆E is the energy splitting of the first doublet. Experiments performed with N H 3 [4], N D 3 [5] and N T 3 [6] reveal the existence of this inversion line in various rotational and vibrational bands. The frequencyν of the inversion line has been measured as a function of the gas pressure P for N H 3 [7,8] and N D 3 [9]. Starting fro...

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Interaction Induced Localization in a Gas of Pyramidal Molecules

2002

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“…It is also supported by the large moment, 6.6D, reported for lithium fluoride. The spectra of the partially deuterated ammonias have been investigated by Kyhl,12 Lyons et al, 13 and Weiss and Strandberg. This is incorrect since roughly 90% of the moment comes from hybridization in the covalent structure.…”

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confidence: 99%

Pure Rotational Spectra of the Partially Deuterated Ammonias in the Far Infrared Spectral Region

Palik

Bell

1957

The Journal of Chemical Physics

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Rotational spectra of NH2D and NHD2 have been measured in the spectral range from 30 to 200 cm-I . The inversion splitting of the NH2D lines has been observed. The spectra have been analyzed to obtain term values for many of the low J rotational levels of the ground states of those molecules. The effects of centrifugal distortion on the energy levels is discussed. Molecular constants and dimensions are obtained.

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“…Such motional Stark shifts have already been seen experimentally, but have not hitherto been interpreted in terms of the HMW phase [15][16][17]. We also propose a different direct HMW phase measurement using a Ramsey two-pulse interferometer with ammonia beams and microwaves [20].…”

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confidence: 92%

“…The HWM phase becomes ϕ HMW a d BL c = / h , where d a is now the ammonia dipole moment. However, both inversion states of the ammonia molecule are stable, and hence one has time to use two-pulse Ramsey spectroscopy on the system, as was done in 1951 with the first ammonia molecular clock experiments of Lyons, et al [20]. The set up would be the same as in Fig.…”

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Maxwell Duality, Lorentz Invariance, and Topological Phase

1999

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We discuss the Maxwell electromagnetic duality relations between the Aharonov-Bohm, Aharonov-Casher, and He-McKellar-Wilkens topological phases, which allows a unified description of all three phenomena. We also elucidate Lorentz transformations that allow these effects to be understood in an intuitive fashion in the rest frame of the moving quantum particle. Finally, we propose two experimental schemes for measuring the He-McKellar-Wilkens phase.Comment: 10 pages, 2 figure

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Microwave Spectra of Deutero-Ammonias

Cited by 21 publications

References 7 publications

Interaction Induced Localization in a Gas of Pyramidal Molecules

Interaction Induced Localization in a Gas of Pyramidal Molecules

Pure Rotational Spectra of the Partially Deuterated Ammonias in the Far Infrared Spectral Region

Maxwell Duality, Lorentz Invariance, and Topological Phase

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