Nuclear Quadrupole Frequency Research Articles

Pressure and Temperature Dependence of the Nuclear Quadrupole Frequency of 23Na in NaBrO3

The temperature and pressure dependences of the nuclear quadrupole coupling frequency of 23Na in NaBrO3 have been measured. The quadrupole frequency is found to range from 886 kHz at 4.1°K to 849 kHz at 300°K at atmospheric pressure. The pressure dependences were determined at 196°, 273°, and 298°K. From the pressure dependences and the compressibility the frequency was found to vary with the volume about as V−2.5 at all three temperatures. The rate of change in frequency with temperature at a constant volume, ν−1(∂ν / ∂T)v, was found to have a positive value and to decrease in magnitude with increasing temperature above 196°K.

BEEM-πcalculations on chlorine in conjugated molecules

The bond electronegativity equalization method for σ bonds is combined with the Huckel molecular orbital method for π bonds to give a SCF σ-π treatment for conjugated molecules. The method, BEEM-π, is used to calculate the nuclear quadrupole frequencies of 35Cl in conjugated systems; the frequencies agree well with experiment.