Accession Number:

AD0256310

Title:

EXCHANGE-ORDERING AND OBSERVATION OF FORBIDDEN SPIN RESONANCE TRANSITIONS IN CRYSTALLINE ORGANIC RADICALS

Descriptive Note:

Corporate Author:

STANFORD UNIV CALIF

Report Date:

1961-04-01

Pagination or Media Count:

1.0

Abstract:

IN EXAMINING THE E. S. R. electron spin resonance spectrum of polycrystalline samples of the organic free radicals picryl-n-amino carbazyl PAC, 1-3-bis diphenylene-2-phenyl allyl BDPA, and Wursters blue perchlorate WB at low temperatures and low frequencies, a resonance was observed at g 4. This line may have arisen from a forbidden transition made possible by the dipolar interaction between spins. In the frequency range from 20 mc to 200 mc the gvalue is 4 to within 3 independent of temperature. At fixed temperature the ratio of the peak intensity of the g 4 resonance absorption to that of the g 2 absorption decreases with the increasing frequency. At fixed frequency the intensity ratio decreases with increasing temperature and vanishes above a temperature T characteristic of the particular free radical. The intensity ratio decreases with increasing values of the radio-frequency power. The width of the g 4 resonance appears to be essentially independent of temperature and is of the same order of magnitude as that of the g 2 resonance. In some cases there is evidence for a g 6 resonance in the form of a weak bump on the low field side of the g 4 resonance. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE