D. A. Bozanic

Electron Spin‐Echo Studies of Relaxation Processes in High‐Spin Ferrimyoglobin

The spin‐echo technique is used to study the relaxation processes associated with the trivalent iron ion in horse heart myoglobin at 1.2°K. The destruction of transverse and longitudinal phase memory, as, respectively, measured by the two‐pulse (T2p) and three‐pulse (T3p) echo sequences, is attributed to a spectral diffusion process. Saturation‐recovery data help to affirm this belief. The diffusion process is not dependent upon the concentration of myoglobin in a water solution, which means that it is not dependent upon the Fe3+ concentration (over the range 1017–1019 Fe3+ ions/cc). Moreover, values of T2p and T3p are the same for myoglobin powder as they are for hemoglobin powder. Both of these observations support the conclusion that interactions between the iron spins do not play a major role in the destruction of phase memory; but, rather, that the interaction between the iron magnetic dipoles with the surrounding nuclear moments (particularly the hydrogen nuclei of the water molecule at the sixth li...

Spectrum Analysis of Spin‐Echo Signals in Iron‐Doped Rutile

X‐band electron spin echoes have been obtained at 4.2°K in iron‐doped rutile. The frequency spectrum of these echoes was observed on a conventional spectrum analyzer and compared to the spectrum of the input pulses. Not only is it possible for the echo frequency response to be a good replica of the input pulse response, but there is no observed distortion of the echo response vs delay time over the time interval investigated (5–50 μsec). This latter result of no frequency distortion versus delay time for the time interval investigated is in agreement with the fact that the spectral diffusion time constant (as measured by the three‐pulse stimulated echo technique) was found to be no less than one millisecond. It is shown, however, that for two identical input pulses the turning angle can be no greater than 120° if good spectral reproducibility is desired. Echoes were also observed simultaneously at two different frequencies within the same resonance line and the same microwave cavity mode with no distortin...