Temperature and Pressure Dependence of the Nuclear Quadrupole Resonance of14N in (CH2)6N4

1966 ◽  
Vol 44 (11) ◽  
pp. 4171-4177 ◽  
Author(s):  
G. A. Matzkanin ◽  
T. N. O'Neal ◽  
T. A. Scott ◽  
P. J. Haigh
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Pressure Dependence ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole

Temperature and Pressure Dependence of 35Cl Nuclear Quadrupole Resonance in BiCl3

1973 ◽  
Vol 51 (14) ◽  
pp. 2290-2291 ◽  
Author(s):  
G. C. Gillies ◽  
R. J. C. Brown
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Pressure Dependence ◽  
Constant Pressure ◽  
Temperature Coefficients ◽  
Quadrupole Resonance ◽  
Intermolecular Bonding ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole ◽  
35Cl Nuclear Quadrupole Resonance ◽  
Volume Effects

The temperature and pressure dependences of the two 35Cl nuclear quadrupole resonances in BiCl3 have been measured. At constant pressure, the temperature coefficients are markedly different and this difference is shown to be due to volume effects associated with different intermolecular bonding.

Temperature and pressure variation of the 35Cl nuclear quadrupole resonance frequency in K2OsCl6

1970 ◽  
Vol 48 (20) ◽  
pp. 2411-2419 ◽  
Author(s):  
Robin L. Armstrong ◽  
Gregory L. Baker
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Coefficient Of Thermal Expansion ◽  
Pressure Variation ◽  
Temperature Phase ◽  
Thermodynamic Relation ◽  
Lattice Mode ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole

Measurements of the temperature and pressure dependence of the 35Cl nuclear quadrupole resonance (NQR) frequency in K2OsCl6 are reported. The resonance frequency is measured at atmospheric pressure for temperatures from 4.2 to 430 °K and for five temperatures between 284 and 410 °K for pressures to 5000 kg cm−2. A second-order phase transition occurs at about 45 °K. In the high temperature phase all of the chlorine atoms are crystallographically equivalent. The analysis carried out deals exclusively with the data obtained in this phase. A thermodynamic relation is used to relate the experimental quantities (∂v/∂T)P and (∂v/∂P)T to the theoretical quantity (∂v/∂T)V. The latter quantity is calculated for a particular model to describe the motional averaging of the electric field gradient at the chlorine sites. The model adopted includes two distinct mechanisms—the usual Bayer–Kushida averaging mechanism and a mechanism resulting from the partial destruction of π bonding by the lattice vibrations. The thermodynamic relation is used in conjunction with the combined data for K2PtCl6, K2IrCl6, and K2OsCl6 to evaluate the validity of the model proposed. It is concluded that the model provides a consistent explanation of both the temperature and pressure variation of the NQR data. In addition, the analysis provides information on the nature of the molecular orbitals of the [MCl6]2− complex ion, gives a rough estimate of the ratio of the coefficient of thermal expansion to the isothermal compressibility, and lastly, yields a value for the average frequency of the rotary lattice mode in the three substances.

Investigation of the Rotary Lattice Mode in R2PtCl6 Compounds. I. From Measurements of the 35Cl Nuclear Quadrupole Resonance Frequency

1971 ◽  
Vol 49 (19) ◽  
pp. 2381-2388 ◽  
Author(s):  
Douglas F. Cooke ◽  
Robin L. Armstrong
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Atmospheric Pressure ◽  
Nuclear Quadrupole Resonance Frequency ◽  
Published Data ◽  
Lattice Mode ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole ◽  
Static Lattice

Measurements of the temperature and pressure variation of the 35Cl nuclear quadrupole resonance (NQR) frequency in Rb2PtCl6 and Cs2PtCl6 are reported. The resonance frequency is measured at atmospheric pressure for temperatures from 4 to 500 K and at four temperatures between 290 and 380 K for pressures to 5000 kg cm−2. Previously published data for K2PtCl6 are also included in the analysis. Static lattice NQR frequencies are deduced. The differences between the static lattice frequencies are compared with the calculations of Smith and Stoessiger. Thermal averaging of the electric field gradient at a chlorine site is assumed to be dominated by the Q3, Q4, Q5, and Q6 internal modes of the PtCl6 octahedra and by the rotary lattice mode. The rotary mode frequencies are deduced; they are of similar magnitude and increase in the same sequence as the frequencies deduced from infrared and Raman data. An analysis of the pressure dependence of the NQR frequencies leads to pressure coefficients for the rotary mode frequencies. The influence of the cage of R atoms surrounding a PtCl6 octahedron is shown to increase through the series K2PtCl6, Rb2PtCl6, Cs2PtCl6. Finally, a thermodynamic analysis of the NQR data is presented which shows the importance of taking specific volume effects into account.

Temperature and Pressure Dependence of 209Bi Nuclear Quadrupole Resonance in BiCl3

1972 ◽  
Vol 50 (16) ◽  
pp. 2586-2590 ◽  
Author(s):  
G. C. Gillies ◽  
R. J. C. Brown
Keyword(s):  
Pressure Dependence ◽  
Room Temperature ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole ◽  
Crystal Volume

The temperature and pressure dependence of the 209Bi nuclear quadrupole coupling constant and asymmetry parameter in solid BiCl3 have been measured near room temperature. It is not possible to account for the results on the basis of the conventional theory in which the field gradient parameters depend only on the crystal volume.

Nuclear quadrupole resonance and intermolecular interactions: temperature and pressure effects in Group V trichlorides

1976 ◽  
Vol 54 (14) ◽  
pp. 2266-2279 ◽  
Author(s):  
Grant Callum Gillies ◽  
Richard Julian Challis Brown
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Pressure Coefficient ◽  
Pressure Effects ◽  
Group V ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Temperature Dependences ◽  
Intermolecular Bonding ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole

Nuclear quadrupole resonance frequencies for the metal and chlorine atoms in AsCl3 and SbCl3 have been measured as functions of temperature and pressure. These data are analysed to obtain the isothermal volume dependences and the isochoric temperature dependences of the field gradient parameters. Existing knowledge of the Group V trichlorides shows that the strength of intermolecular bonding increases in the order AsCl3 < SbCl3 < BiCl3, and this trend is reflected in the relative importance of volume effects in determining the nqr frequencies in these solids. A simple theory of the pressure dependences of nqr frequencies in molecular crystals is proposed, which accounts for all data presently available. The pressure coefficient contains static and dynamic contributions which are of opposite signs; the static contribution is negative and becomes numerically larger as the strength of intermolecular bonding increases.

Pressure dependence of chlorine nuclear quadrupole resonance in sodium chlorate

1972 ◽  
Vol 7 (6) ◽  
pp. 615-619 ◽  
Author(s):  
M.S. Vijaya ◽  
J. Ramakrishna ◽  
A.S. Reshamwala ◽  
A. Jayaraman
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Pressure Dependence ◽  
Sodium Chlorate ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole
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