Radio frequency continuous wave

A unique process for chemical stabili2ation of a ceUular elastomer upon extmsion has been shown for ethylene—propylene mbber the expanded mbber obtained by extmsion is exposed to high energy radiation to cross-link or vulcani2e the mbber and give dimensional stabUity (9). EPDM is also made continuously through extmsion and a combination of hot air and microwaves or radio frequency waves which both activate the blow and accelerate the cure. 

Electron-nuclear double resonance (ENDOR) spectroscopy A magnetic resonance spectroscopic technique for the determination of hyperfine interactions between electrons and nuclear spins. There are two principal techniques. In continuous-wave ENDOR the intensity of an electron paramagnetic resonance signal, partially saturated with microwave power, is measured as radio frequency is applied. In pulsed ENDOR the radio frequency is applied as pulses and the EPR signal is detected as a spin-echo. In each case an enhancement of the EPR signal is observed when the radiofrequency is in resonance with the coupled nuclei. 

In the conventional NMR experiment, a radio-frequency field is applied continuously to a sample in a magnetic field. The radio-frequency power must be kept low to avoid saturation. An NMR spectrum is obtained by sweeping the rf field through the range of Larmor frequencies of the observed nucleus. The nuclear induction current (Section 1.8.1) is amplified and recorded as a function of frequency. This method, which yields the frequency domain spectrum f(ai), is known as the steady-state absorption or continuous wave (CW) NMR spectroscopy [1-3]. 

In continuous-wave experiments (single resonance), the super-Hamiltonian HD includes an additional component which represents interactions with the radio-frequency magnetic field Bx rotating in the same direction as the Larmor precession (21)... 

A2. Alderman, D. W., Improvement of signal-to-noise ratio in continuous-wave nuclear magnetic resonance at liquid-helium temperature by using a metal oxide semiconductor field-effect-transistor radio-frequency amplifier. Rev. Set. Instrum. 41, 192-197 (1970). 

High resolution NMR spectrometers can be categorized into continuous wave (CW) and pulsed FT, both of them requiring a radio-frequency source and a magnetic field. As... 

The SFC is a critical parameter for the fats and oils industry. The official American Oil Chemists Society (AOCS) wet method is dilatometery. Alternative wet methods are differential thermal analysis and differential scanning calorimetry (DSC). LR NMR was proved to be an alternative method for SFC determination in late 1950s. The early continuous wave LR NMR spectrometers rapidly found their way into the fats and oils industry, the method being accepted by the Instrumental Techniques Committee of the AOCS as early as in 1972. Presently the technical choice is radio frequency (RF) pulsed LR NMR. Pulse NMR spectrometers are more compact, very efficient, and relatively cheap. They have the advantage of exciting the protons in the whole sample at once. 

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