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.
Magnetic Resonance Spectroscopy of Triplet‐State Organic Molecules in Zero External Magnetic Field
Some derivations are given for approximations to the energy levels and eigenstates of triplet‐state organic molecules in external magnetic fields of such a magnitude that the electron Zeeman interaction is small relative to the intramolecular electron–electron interaction. An exact calculation of the exactly zero external field magnetic resonance spectrum of photoexcited naphthalene is given. Experimental measurements of the zero‐field spectrum of naphthalene are presented. The results of the approximate and exact treatments are compared with these results and with other available experimental information.
Optical rotatory dispersion and absolute configuration—III
Abstract Optical rotatory dispersion measurements on pyrrolidine, piperidine, and tetrahydro-isoquinoline alkaloids indicate that the absolute configuration of the α-asymmetric center may be assigned directly from the dispersion curve, provided either that the nitrogen atom is not protonated, or that the compound contains a chromophore absorbing above 200 mμ.