Electron paramagnetic susceptibility and conduction electron spin resonance in hexaamminecalcium(zero)

摘要

The magnetic susceptibility of Ca(NH3)6has been measured by the Faraday method over the range 1.5minus;300deg;K. The observed molar susceptibility, after correction for diamagnetism, decreases linearly from 130times;10minus;6at room temperature to 85times;10minus;6at 100deg;K, then rises linearly to 140times;10minus;6at 20deg;K, and finally falls rapidly to 60times;10minus;6at 1.5deg;K. The behavior below 100deg;K is reminiscent of that previously reported for Li(NH3)4and may be due to an incipient metalminus;nonmetal transition. Conduction electron spin resonance (CESR) atXminus;band frequency has been measured for Ca(NH3)6over the temperature range 4.2minus;240deg;K. The absorption signal is Dysonian and its second derivative peakminus;tominus;peak linewidth decreases linearly with temperature to about 40deg;K, below which the decrease becomes more rapid. The spinminus;lattice relaxation time varies approximately asTminus;1, even at very low temperatures. The measuredgshift (minus;5times;10minus;4) is small and independent of temperature; the small value relative to Ca suggests that the wavefunction of the conduction electrons at the Fermi level possesses morescharacter in Ca(NH3)6than it does in Ca.