Hyperfine Structure in the Spectrum of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow><mml:mrow><mml:mn>14</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>. I. Experimental Re

Gunther-Mohr, G. R.; White, Robert L.; Schawlow, A. L.; Good, William E.; Coles, Donald K.

doi:10.1103/physrev.94.1184

Cited by 71 publications

(11 citation statements)

References 13 publications

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“…4 The corresponding value of −5.47 MHz reported for trimethyl amine 3 is slightly higher. It is interesting to compare this value with values for ammonia 1 and nitrogen trifluoride NF 3 , 5 which are 10 −4.0842 MHz and −7.903 MHz, respectively. The value for ammonia is much lower and the one for nitrogen trifluoride much higher.…”

Section: Resultsmentioning

confidence: 98%

Microwave survey of the conformational landscape exhibited by the propeller molecule triethyl amine

Nguyen

Kannengießer

Stahl

2012

Phys. Chem. Chem. Phys.

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Conformational studies with quantum chemical methods yielded for the most stable conformer of triethyl amine a propeller-like structure belonging to the point group C(3), which corresponds to an oblate top. The microwave spectrum of this conformer with (14)N hyperfine splitting of all rotational transitions was assigned and molecular parameters were determined. The rotational constants were found to be A = B = 2.314873978(11) GHz, the (14)N quadrupole coupling constant χ(cc) = -5.2444(07) MHz. The observed spectrum could be reproduced within experimental accuracy. The standard deviation of a global fit with 48 rotational transitions is 1.5 kHz. The propeller-like structure seems to be energetically favorable and therefore also typical for related systems like triethyl phosphine, triisopropyl amine, tri-n-propyl amine, and tri-tert-butyl amine. Furthermore, the rotational transitions of two isotopologues, (13)C(2) and (13)C(5), could be measured in natural abundance and fitted with an excellent standard deviation. The C rotational constants could be determined to be 1.32681(96) GHz and 1.32989(18) GHz for the (13)C(2) and (13)C(5) isotopologues, respectively.

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Section: Resultsmentioning

confidence: 98%

Microwave survey of the conformational landscape exhibited by the propeller molecule triethyl amine

Nguyen

Kannengießer

Stahl

2012

Phys. Chem. Chem. Phys.

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“…One obvious route by which the parity degeneracy might be lifted is tunneling [ Fig. 2(a)], by direct analogy with the well-known case of ammonia [1,9], and there have been numerous attempts to observe this possibility [10,11]. The degeneracy can be further lifted through the hyperfine interactions [ Fig.…”

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confidence: 98%

Hyperfine lifting of parity degeneracy and the question of inversion in a rigid molecule

1993

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This Letter demonstrates that the parity degeneracy of isolated vibration-rotation states of a rigid molecule can be removed by hyperfine interactions. Hyperfine structures of infrared transitions in PH3 are obtained by saturation spectroscopy around 10 fim. One of these is used to demonstrate unequivocally that degenerate states of opposite parity are separated by the proton hyperfine interactions. We show that alternative explanations involving the physical inversion of the molecule are completely inconsistent with the details of the spectra obtained. In addition to the splitting conclusion, which has very wide generality, new confidence limits are placed on the possible inversion splitting.PACS numbers: 33.20.Ea, 35.20.Jv, 35.20.Sd The degrees of freedom of most molecules in their ground electronic levels can be divided among translations, vibrations, rotations, large amplitude motions, and nuclear spin. Among large amplitude motions inversion plays a peculiar role since parity, the associated quantum number, is always good because of the invariance property of space under inversion in the absence of weak interactions. When a molecule inverts freely it is not surprising to find that the degeneracy of levels of opposite parity is lifted. The first important result of this paper is to show experimentally, via the example of phosphine, that the degeneracy will be lifted even for a rigid molecule in which there is no inversion. We show, further, that this result is intimately connected to the Pauli principle and that there can be no essential degeneracy with parity.Following earlier work on hyperfine effects in ammonia, we will classify the vibration-rotation and hyperfine states of a rigid molecule such as phosphine (PH3) under the geometrical point group C-$ v [1,2] and use the Landau [3] and Berger [4] notations. The rovibrational states are characterized by quantum numbers / and k for total orbital angular momentum and its component along the symmetry axis, respectively, while A^l&l. v is the quantum number for vibrational excitation, and / is the quantum number for the corresponding component of angular momentum along the symmetry axis. Thus, for example, the degenerate V4 state excited to the level 1*4-1 has / = ± 1. Finally, the parity, r =( ± ), completes the description of the rovibrational states. For symmetric top molecules, it is convenient to introduce the symmetric (s) and antisymmetric (a) character of a state upon reflection in a plane perpendicular to the symmetry axis. The correspondence between r and v is r =(+) if v ~(s) and K even or if v=(a) and K odd; otherwise, r^C -). States having k~l -± 3n form a representation A\+Ai except when k ~/=0, the states then being either A\ or A2 depending upon J and r. States having k -I = ± (3n + 1) or ± On 4-2) are of symmetry E. /p, the nuclear spin of 3l P, is j and the corresponding symmetry must necessarily be A\ as the atom is certainly on the symmetry axis. Then, the total proton spin, l\\, must be included. Proton spin states with I\\ = j and /H -...

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“…a flow system with argon as a buffer gas to ensure low The ground state hyperfine measurements of ammonia ammonia pressures of about 4 mbar and in turn minimize have significantly contributed to the development of the ma-pressure shifts. More detailed description of this saturation ser beam techniques (7)(8), and the analysis of its spectrum experiment can be found in Refs. (16,17).…”

Section: Experimental Details and Resultsmentioning

confidence: 99%

Hyperfine Structure of Rotation-Inversion Levels in the Excited ν2State of Ammonia

Белов

Urban

Winnewisser

1998

Journal of Molecular Spectroscopy

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Hyperfine Structure in the Spectrum ofN14H3. I. Experimental Re

Cited by 71 publications

References 13 publications

Microwave survey of the conformational landscape exhibited by the propeller molecule triethyl amine

Microwave survey of the conformational landscape exhibited by the propeller molecule triethyl amine

Hyperfine lifting of parity degeneracy and the question of inversion in a rigid molecule

Hyperfine Structure of Rotation-Inversion Levels in the Excited ν2State of Ammonia

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