Hard pulse energy

For the most part, pulses have been generated by applying rf energy equally over the entire frequency range, with a short duration on the order of microseconds. Such excitations are sometimes referred to as hard pulses, in distinction to pulses that require selective excitation (i.e., excitation over a restricted frequency range). Selective excitation has been mentioned on several occasions. It is useful, for example, in the saturation transfer experiment... 

Fig. 14. Schematic of selective excitation and ID exchange spectroscopy, (a) Typical pulse sequence with a soft selective pulse centered at pulsation a>s with a frequency dispersion AcoP <3C Aoj much smaller than the typical linewidth. After an evolution time te smaller or of the order of the spin-lattice relaxation time, a reading sequence of hard pulses that covers uniformly the whole broad line is applied, (b) Effect of a selective excitation on a homogeneously broaden line, (c) Selective frequency labeling of an inhomogeneously broaden line at the irradiation pulsation cos of the first soft pulse. For a soft n pulse, the magnetizations of all the spins that can exchange energy at this pulsation are reversed. By following the difference spectra between the spectra acquired at different evolution times te and the fully relaxed spectrum AS(te) — S(t -> oo) — S(te), limits or evaluation of the correlation time tc of the motion can be achieved.

The inelastic scattered gammas from nitrogen are very weak and hard to detect in the detector pulse continuum. With low-energy resolution gamma detectors... 

Note that SPODS is nearly always operative in resonant strong-held excitation using modulated ultrashort laser pulses, the only exception being so-called real laser pulses [72, 77] (i.e., electric helds with only one quadrature in the complex plane) that are usually hard to achieve in ultrafast laser technology. This is why many different pulse shapes can lead to comparable dressed state energy shifts and... 

Time-resolved chemiluminescence spectra are obtained as follows. For a given optical path difference, the entire temporal profile of the pulse of product IR chemiluminescence is recorded at the detector, amplified, digitized (up to 10 ns resolution) and stored directly on hard disc for a preset number of photolysis laser shots, the number depending on the SNR of the system. The C02 laser energy for each shot is recorded by a pyroelectric... 

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