PULSED RF EXCITED SPECTROMETER HAVING IMPROVED PULSE WIDTH CONTROL

摘要

Application for PatentofHoward D.W. HillforPULSED RF EXCITED SPECTROMETERHAVING IMPROVED PULSE WIDTH CONTROLABSTRACT OF THE DISCLOSURERF excitation for a spectrometer is obtained by pulsewidth modulating an RF carrier to produce the desired broad-band RF exciting spectrum. The RF excitation includes atrain of composite RF pulses, each composite pulse having aprimary pulse portion of a first RF phase and a second pulseportion of a second RF phase opposite that of the first. Inthis manner, the finite rise and fall times of the primarypulse portion are compensated for by the corresponding riseand fall times of the secondary pulse portion. The primarypulse portion is lengthened by an amount equal to the secondarypulse portion so that the secondary pulse portion cancels theadded primary pulse portion. In a spectrometer the compensatingsecond pulse component removes certain undesired side bands ofthe RF excitation caused by the finite rise and fall times ofthe applied RF pulses. The compensating second pulse componentremoves certain undesired side bands associated with each ofthe resonant lines of the excited resonance spectrum, therebysimplifying the resonance spectrum of the sample under analysis,particularly for wide band RF excitation.-1-