The Pure Rotation Spectrum of Ammonia

Badger, Richard M.; Cartwright, C. Hawley

doi:10.1103/physrev.33.692

Cited by 45 publications

(5 citation statements)

References 8 publications

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“…4 The magnitude of the dipole is large, 6.04D. This is in accord with three other indirect lines of evidence: (c) The electrolysis of molten lithium hydride which yields hydrogen at the anode.…”

Section: Discussionsupporting

confidence: 79%

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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Section: Discussionsupporting

confidence: 79%

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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“…The first measurement of the spectrum of ammonia dates back prior to 1905. 1 Several further measurements, and their interpretations, followed in the 1920s, [2][3][4][5][6][7][8][9][10][11] 1930s, [12][13][14][15][16][17][18][19][20][21][22][23] and 1940s. [24][25][26][27][28][29][30][31][32][33][34][35] A large number of the later experimental studies are nicely summarized and reviewed in ref.…”

Section: Introductionmentioning

confidence: 99%

Promoting and inhibiting tunneling via nuclear motions

Császár

Furtenbacher

2016

Phys. Chem. Chem. Phys.

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Accurate, experimental rotational-vibrational energy levels determined via the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm and published recently for the symmetric-top (14)NH3 molecule in J. Quant. Spectrosc. Radiat. Transfer, 2015, 116, 117-130 are analyzed to unravel the promoting and inhibiting effects of vibrations and rotations on the tunneling splittings of the corresponding symmetric (s) and antisymmetric (a) rovibrational energy level pairs. The experimental transition data useful from the point of view of the present analysis cover the range 0.7-7000 cm(-1), sufficiently detailed rovibrational energy sets worth analyzing are available for 20 vibrational bands. The highest J value, where J stands for the rotational quantum number, within the experimental dataset employed is 30. Coupling of the "umbrella" motion of (14)NH3 with other vibrational degrees of freedom has only a minor effect on the a-s tunneling splitting characterizing the ground vibrational state, 0.79436(70) cm(-1). In the majority of the cases rotation around the C3 axis increases, while rotation around the two perpendicular axes decreases the tunneling splittings. For example, for the pair of vibrational ground states, 0(+) and 0(-), the tunneling splitting basically disappears at around J = 25 for the (J,K) = (J,1) states, where K = |k| is the usual quantum number characterizing the projection of the rotational angular momentum on the principal axis. The tunneling splittings, defined as energy differences E(a) - E(s) of corresponding energy level pairs, as a function of J and K show a very regular behavior for the ground state (GS) and the nν2 bands. For the other bands investigated exceptions from a regular behavior do occur, especially for bands characterized by degenerate vibrations, and occasionally the data available are not sufficient to arrive at definitive conclusions. The most irregular behavior is observed for rotational states characterized by the k - l = 3n rule (l is the vibrational angular momentum quantum number), with n = 0, 1, 2,… High-quality, variationally computed rovibrational data support all the conclusions of this study based on experimental energy levels.

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“…NH 3 provides a striking example, which was first recognized from the split infrared absorption lines, recorded by Badger and Cartwright in 1929 [6]. An extended analysis of the rules that govern spectroscopic transitions for such cases was outlined in detail by Herzberg [7].…”

Section: Rotation/inversionmentioning

confidence: 99%