A New Zero‐Field Paramagnetic Resonance Spectrometer
The construction of a new zero‐field paramagnetic resonance (ZFPMR) spectrometer is discussed. Spectrometer organization and construction details are presented for both resonant cavities and broadband traveling‐wave helices as sample holders. A new circuit diagram for a square wave magnetic field modulator with fast rise time is given. The performance of each kind of spectrometer is discussed with particular emphasis on investigation of paramagnetic rare earth ions with zero‐field splittings in diamagnetic host lattices.
Cyclotron resonance and carrier scattering processes in anthracene crystals
Cyclotron resonance experiments on holes orbiting in the ab plane of an anthracene crystal are described in detail. We were unable to reduce the cyclotron resonance experiment to a routine procedure and consequently are able to report useful cyclotron resonance measurements on only a few (six) anthracene crystals. Nevertheless we have been able to obtain useful information on the valence band structure and hole scattering properties in anthracene from these measurements. The measured effective mass of 11 me, where me is the free electron mass, is shown to be in qualitative agreement with calculations of the effective mass tensor. From the shape of the cyclotron resonance line at 2 K, we have obtained experimental hole scattering times ranging from 4×10−10 sec down to 10−12 sec and below depending on sample quality. By a detailed examination of the possible low temperature scattering mechanisms, we have concluded that, at 2 K, holes in anthracene are most efficiently scattered by charges trapped at point d...
Experience of using rating scales for the assessment of vocational trainees in general practice.
For two years trainers in the northern half of the south western region have been asked to assess their trainees with a condensed version of the new Manchester rating scales for vocational training in general practice and to send copies to the regional adviser. The condensed version retains the 23 scales but does not include the subscales. Trainers' workshops and comments from individuals suggested that no radical improvements to the scales were required and that they were an adequate statement of what was required from trainees. The response rate of 89% for returning at least one assessment and 38% for returning all three suggested that use of this condensed version would be more feasible than using the full version of the scales. Analysis of 86 first assessments and 48 sets of three assessments showed a range of variation both in trainee ratings and use of individual scales that was consistent with expectations. A lack of significant rank correlations between the scales indicated that each of the scales measured a different characteristic of behaviour. We suggest that the most useful way to achieve systematic assessment of vocational trainees is by the use of the 23 main rating scales, with regional variations where appropriate.