| With inelastic neutron scattering experiments the tunneling splittings of the order of 1 (mu)eV and higher can be determined, while with Spin Polarization Torsional Spectroscopy (SPOTS) tunneling splittings of 10('-5) to 10('-3) (mu)eV are observable. The gap in energies covered by these two methods has been bridged by order transfer NMR, a tunneling spectroscopy introduced in this thesis. This new spectroscopy is an efficient technique for measuring the tunneling splittings, the Zeeman - torsional coupling time and the ratio of the specific heats of Zeeman and torsional systems.; In the order transfer method, a train of 90(DEGREES) r.f. pulses is applied and the magnetization monitored after each pulse. Near the tunneling - Zeeman resonance (omega)(,o) = (omega)(,T) or 2(omega)(,o) = (omega)(,T) the tunneling levels are strongly coupled to the proton Zeeman system in the laboratory frame ((omega)(,o)/2(pi) is the proton Larmor frequency and (omega)(,T)/2(pi) is the tunneling frequency). During the delay between two successive pulses (mixing period), a transfer of polarization (order) from the tunneling to the Zeeman system takes place. The time characterizing this flow is minimum at resonance. If the magnetizations following each pulse of a tunneling saturation train are added together, the total tunneling order transferred to the Zeeman system is obtained. From it the ratio of the specific heats C(,T)/C(,Z) is obtained. C(,T) and C(,Z) are the specific heats of the torsional and Zeeman system respectively.; This new spectroscopic technique has been used to study Ge(CH(,3))(,4) at 37.5 K at several proton Larmor frequencies. The tunneling frequency was found to be (omega)(,T)/2(pi) = 86.4 (+OR-) 0.06 MHz and the Zeeman - torsional coupling time 2.6 ms. The specific heats of the Zeeman and torsional systems were found to be nearly equal C(,T)/C(,Z) = 0.96 (+OR-) 0.05. |
