| 摘要 |
<p>1,081,724. Electro-physical measurement. VARIAN ASSOCIATES. May 28, 1965 [June 5, 1964], No.22838/65. Heading G1N. In a gyromagnetic spectrometer to determine electron-nuclear double resonance with large amplitude R. F. fields, the R. F. supply is pulsed to reduce heating of the sample and resonant cavity, and to prevent spurious radio frequency, interaction with the E. P. R. signal detector, the circuit is gated synchronously with the pulses and applied to a narrow band amplifier tuned to the pulse repetition frequency. A first pulsed R. F. field may be used having a frequency near the N. M. R. point with a second R. F. field having a slightly different frequency applied intermediate the first series of pulses. The detector output signal is proportional to the difference between the electron-nuclear resonance at the frequencies of the first and second fields. A spectrum may be obtained by "scanning" the R. F. fields. Alternatively a bucking magnetic field may be applied at the pulse repetition frequency to oppose the polarizing field and balance out the field shift due to the R. F. pulse. The apparatus is applicable to the analysis of free radicals with strongly coupled protons in liquid, such as n-heptane.</p> |
