Lattice dynamical effects in the frequency analysis of the infrared and Raman spectra of solid parahydrogen

1970 ◽  
Vol 48 (17) ◽  
pp. 2032-2055 ◽  
Author(s):  
J. Noolandi
Keyword(s):  
Intermolecular Interaction ◽  
Frequency Analysis ◽  
Perturbation Scheme ◽  
Lattice Vibrations ◽  
Coupling Constant ◽  
Phonon Interaction ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Dielectric Screening ◽  
Experimental Values

The frequency perturbations of the rotation–vibration levels in solid H2, due to the modulation of the anisotropic and vibrational intermolecular interaction by the lattice vibrations, are calculated. The lattice vibrations are treated in the self-consistent harmonic (SCH) approximation with short-range correlations, and the intermolecular interaction is expanded in terms of the quantum crystal phonon operators. The discrepancy between previous calculations of the effective quadrupolar coupling constant and the experimental values is resolved when the roton–phonon interaction is properly renormalized to take into account the long-range phonon correlations. The energy of the induced dipoles in the quadrupolar field of all the H2 molecules in the crystal (dielectric screening energy) is considered, and in particular the effect of this induction energy on the roton band energies is calculated. The frequencies of the infrared and Raman S0(0) lines are analyzed, taking into account the frequency shifts due to the roton–phonon interaction and the dielectric screening energy, and a value of the effective quadrupolar coupling constant which is consistent with other experimental values is derived. New values of the crystalline field constants ε2C and ε4C are given. The shift and splitting of the S1(0) Raman line is recalculated, taking into account the interaction with the lattice vibrations, and the splitting of the S1(0) + S1(0) doublet in the overtone infrared spectrum is calculated using a different perturbation scheme from the previous calculations. The limitations on the frequency analysis due to the uncertainty in the roton–phonon coupling parameters are discussed.

Effect of the lattice vibrations on the rotational excitations in solid hydrogen

1970 ◽  
Vol 48 (6) ◽  
pp. 675-686 ◽  
Author(s):  
J. Noolandi ◽  
J. Van Kranendonk
Keyword(s):  
Short Range ◽  
Energy Levels ◽  
Order Reduction ◽  
Second Order ◽  
Lattice Vibrations ◽  
Coupling Constant ◽  
Quantum Crystal ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Short Range Correlations

The theory of the interaction between the lattice vibrations and the rotational excitations in solid H2 is developed using the self-consistent harmonic phonon model with short-range correlations. First- and second-order perturbations in the roton energy levels are calculated using the expansion of the roton–phonon interaction in terms of the quantum-crystal phonon operators derived in a previous paper. The first-order reduction of the quadrupolar coupling constant due to the difference of the longitudinal and transverse sound velocities is calculated and compared with the effect of the short-range correlations. Second-order shifts due to the modulation of the crystalline field and the quadrupolar interactions by the lattice vibrations are also calculated using an isotropic model for the rotons. The roton self-energy shifts are expressed in terms of an effective quadrupolar coupling constant and the dependence of this constant on the roton wave vector is studied. The coupling constant is shown to be appreciably different for propagating and localized rotational excitations.

ESE-ENDOR Study and DFT Calculations on Oxovanadium Compounds:  Effect of Axial Anionic Ligands on the51V Nuclear Quadrupolar Coupling Constant

2004 ◽  
Vol 108 (19) ◽  
pp. 4310-4321 ◽  
Author(s):  
Constantino P. Aznar ◽  
Yiannis Deligiannakis ◽  
Evangelos J. Tolis ◽  
Themistoklis Kabanos ◽  
Marcin Brynda ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Coupling Constant ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Anionic Ligands ◽  
Oxovanadium Compounds

A solid-state NMR investigation of the colossal expansion material, Ag3Co(CN)6

2012 ◽  
Vol 90 (10) ◽  
pp. 891-901 ◽  
Author(s):  
Brett C. Feland ◽  
Guy M. Bernard ◽  
Roderick E. Wasylishen
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Negative Thermal Expansion ◽  
Coupling Constant ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Field Gradients ◽  
Increasing Temperature ◽  
Nmr Properties ◽  
Expansion Behaviour

Presented here is a solid-state NMR investigation of the so-called “colossal expansion” material, Ag3Co(CN)6, a compound that exhibits some of the largest positive and negative thermal expansion properties reported. This study explores the 13C, 15N, and 59Co NMR properties of this material at room temperature and at variable temperatures with the goal of probing the effects of this colossal expansion behaviour on these properties. We found that the flexible nature of the crystal framework leads to a distribution of electric field gradients, and that, oddly enough, no strong correlation is observed between the NMR parameters of Ag3Co(CN)6 and its colossal expansion nature. The 59Co isotropic chemical shift increased and the 59Co nuclear quadrupolar coupling constant decreased with increasing temperature, but neither of these relationships were extraordinary when compared to other octahedral Co(III) complexes. The link between the colossal expansion and the NMR properties of Ag3Co(CN)6 may be the distribution of lattice parameters and hence unusually broad features in the 59Co NMR spectra. The high order of symmetry at the cobalt site resulted in a small quadrupolar coupling constant less than 1 MHz in magnitude. We also observed a |1J(107/109Ag,15N)| value of 96 Hz, the largest 107/109Ag–15N coupling constant reported to date.

scholarly journals A multinuclear NMR and quantum chemical study of solid trimethylammonium chloride

2011 ◽  
Vol 89 (9) ◽  
pp. 1036-1046 ◽  
Author(s):  
Glenn H. Penner ◽  
Renee Webber ◽  
Luke A. O’Dell
Keyword(s):  
Chemical Shift ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Spectroscopic Techniques ◽  
Trimethylammonium Chloride ◽  
Coupling Constant ◽  
High Hydrogen ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Hydrogen Position

The solid salt, trimethylammonium chloride (TMAC), is investigated by a combination of NMR spectroscopic techniques and quantum chemical calculations. Chemical shift and nuclear quadrupolar interaction parameters have been measured for 35Cl, 1H/2H, and 15N/14N. These parameters have also been calculated as a function of the hydrogen position in the N···H···Cl fragment. Overall, the measured parameters are consistent with a structure in which the hydrogen is completely transferred to the nitrogen (i.e., N–H···Cl). The high hydrogen chemical shift (10.9 ppm by 2H CP/MAS) and relatively small deuterium quadrupolar coupling constant (127 kHz) indicate a moderately strong N–H···Cl hydrogen bond. A pronounced deuterium isotope effect on the 35Cl quadrupolar coupling constant is observed.

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