In the Wikipedia article Nuclear magnetic resonance, section Fourier-transform spectroscopy, it says the following:
Fourier-transform spectroscopy Most applications of NMR involve full NMR spectra, that is, the intensity of the NMR signal as a function of frequency. Early attempts to acquire the NMR spectrum more efficiently than simple CW methods involved illuminating the target simultaneously with more than one frequency. A revolution in NMR occurred when short radio-frequency pulses began to be used, with a frequency centered at the middle of the NMR spectrum. In simple terms, a short pulse of a given "carrier" frequency "contains" a range of frequencies centered about the carrier frequency, with the range of excitation (bandwidth) being inversely proportional to the pulse duration, i.e. the Fourier transform of a short pulse contains contributions from all the frequencies in the neighborhood of the principal frequency. The restricted range of the NMR frequencies made it relatively easy to use short (1 - 100 microsecond) radio frequency pulses to excite the entire NMR spectrum.
My 1st question is: what is the general shape of these pulses? Are they simply Gaussian-like pulses, or is it a monochromatic wave of given frequency emitted for a short time?
My second question is: what does the author mean by short pulse of "given carrier" frequency?
As a bonus, I would also enjoy some hints about the other assertions in the quoted text.