Lattice Dynamics of Ammonia

Zeng, W. Y.; Anderson, A.

doi:10.1002/pssb.2221620107

Cited by 16 publications

(12 citation statements)

References 15 publications

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“…Additionally, a calculation of the frequencies of these molecules obtained a slightly higher value for the ν 3 ND of NHD 2 than the ν 3 of the ND 3 . 25 Nevertheless, since both assignments lead to reasonable agreement with Eq. (3), the highest frequency was assigned to the ν 3 of ND 3 given the agreement with the observed ν 3 frequency in pure ND 3 , 6 and this assignment also finds support from the assignment given in an infrared study of low-temperature mixed crystal of NH 3 , NH 2 D, NHD 2 , and ND 3 .…”

Section: A D 2 -Nh 3 Mixturesupporting

confidence: 53%

Hydrogen bonding induced proton exchange reactions in dense D2-NH3 and D2-CH4 mixtures

Borstad

Yoo

2014

The Journal of Chemical Physics

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We have investigated high-pressure behaviors of simple binary mixtures of NH3 and D2 to 50 GPa and CH4 and D2 to 30 GPa using confocal micro-Raman spectroscopy. The spectral data indicate strong proton exchange reactions occur in dense D2-NH3 mixture, producing different isotopes of ammonia such as NH3, NH2D, NHD2, and ND3. In contrast, the proton exchange process in dense D2-CH4 mixture is highly limited, and no vibration feature is apparent for deuterated methane. The vibrational modes of H2 isotopes in D2-NH3 are blue shifted from those of pure H2 isotopes, whereas the modes of D2-CH4 show overall agreement with those in pure D2 and CH4. In turn, this result advocates the presence of strong repulsion and thereby internal pressure in D2-NH3 mixture, which are absent in D2-CH4. In fact, the bond length of hydrogen molecules in D2-NH3, calculated from the present spectral data, is shorter than that observed in pure hydrogen - supporting the enhanced intermolecular interaction in the mixture. Comparing the present spectral results with those previously observed in D2-H2O mixtures further suggests that the strength of repulsive interaction or the magnitude of internal pressure in the mixtures is proportional to the strength of hydrogen bonding in H2O, NH3, and CH4 in decreasing order. Hence, we suggest that the proton exchange is assisted by hydrogen bonding in these molecules.

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Section: A D 2 -Nh 3 Mixturesupporting

confidence: 53%

Hydrogen bonding induced proton exchange reactions in dense D2-NH3 and D2-CH4 mixtures

Borstad

Yoo

2014

The Journal of Chemical Physics

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“…For both H,CO and H,DO crystals, N is equal to 30 for the internal modes, 25 for the lattice modes, and hence 55 for all modes. The corresponding values of A are 1.24%, 6.7%, and 4.6% for H,CO and 0.76%, 6.1%, and 4.2% for D,CO. In other words, with 20 adjustable parameters (7 intramolecular and 13 intermolecular), 110 observed frequencies have been modelled for the two crystals with an overall RMS deviation of about 4.4%.…”

Section: Discussionmentioning

confidence: 91%

Lattice Dynamics of Formaldehyde

Weng

Anderson

1991

Physica Status Solidi (b)

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A simple force constant model is described and applied to the vibrations of solid formaldehyde, H,CO and D,CO. Twenty adjustable parameters are used to obtain the best fit to the lattice mode frequencies and crystal field splittings observed by Raman and infrared spectroscopy. The use of symmetry coordinates to reduce the dimensions of the 96 by 96 original matrix is outlined. The dominant intermolecular interaction is confirmed to be that between carbonyl groups. The dependence of the force constants on interatomic separation is expressed in a simple exponential form.Es wird ein einfaches Kraftkonstantenmodell beschrieben und auf die Schwingungen von festem Formaldehyd, H ,CO und D,CO, angewendet. Zwanzig anpaI3bare Parameter werden benutzt, um die beste Anpassung zu den Gittermodenfrequenzen und Kristallfeldaufspaltungen, die mittels Raman-und IR-Spektroskopie beobachtet werden, zu erhalten. Die Benutzung von Symmetriekoordinaten zur Dimensionsreduzierung der 96 ma1 96-Originalmatrix wird dargestellt. Es wird bestiitigt, dal3 die dominierende intermolekulare Wechselwirkung die zwischen Carbonyl-Gruppen ist. Die Abhangigkeit dcr Kraftkonstanten vom interatomaren Abstand wird in einereinfachen Exponentialform ausgedriickt.

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“…Note that S j is the fraction of the kinetic energy shared by the H-atom in the jth vibrational mode; the factor 1/2 in the third term arises from the fact that in a harmonic oscillator, the kinetic energy is half its total energy. Table 2 lists the six measured internal vibrations frequencies [24,25] of 14 NH 3 in its three phases. To calculate K e (H) using Eq.…”

Section: The Nh 3 Moleculementioning

confidence: 99%