Gated continuous wave

Structural information on ions produced by laser desorption has also been obtained by using infrared multiphoton dissociation processes (73). A pulsed C02 laser was used to form the ions, which were further fragmented either by using sequential pulses from the same laser or by using a gated continuous wave infrared laser. 

Output from both gated continuous wave and pulsed carbon dioxide lasers has been used to desorb ions from surfaces and then to photodissociate them in a Fourier transform ion cyclotron resonance mass spectrometer. Pulsed C02 laser irradiation was most successful in laser desorption experiments, while a gated continuous wave laser was used for a majority of the successful infrared multiphoton dissociation studies. Fragmentation of ions with m/z values in the range of 400-1500 daltons was induced by infrared multiphoton dissociation. Such photodissociation was successfully coupled with laser desorption for several different classes of compounds. Either two sequential pulses from a pulsed carbon dioxide laser (one for desorption and one for dissociation), or one desorption pulse followed by gated continuous wave irradiation to bring about dissociation was used. 

The RF signal at / thus generated is sent to an analog multiplier to adjust its level. The signal, so far being a continuous wave, is then gated by an RF switch to make a pulse. 

FIGURE 5>16 Cross-correlation functions in the continuous-wave (cw) and gated-wave excitation modes. 

Hanson GR, Gates KE, Noble CJ, Griffin M, Mitchell A, Benson S (2004) XSophe-Sophe-XeprView (R). A computer simulation software suite (v. 1.1.3) for the analysis of continuous wave EPR spectra. J Inorg Biochem 98 903-916... 

An electrical signal is generated by an RF tone-burst source. In the beginning, a Colpitts oscillator, or the like, was used as the RF tone-burst source. Nowadays, however, burst waves are gated out from continuous waves by a single pole double throw switch for frequency stability. The output (i.e., voltage) of the source is approximately 10 V... 

The commercial systems for zeta-potential determination using these electro-acoustic effects are typified by the AcoustoSizer 8000 (Matek Applied Sciences) consisting of five main components (Fig. 5). The synthesizer produces a continuous sinusoidal voltage which feeds into the gated amplifier. This creates a sinusoidal voltage pulse across the cell which contains the dispersion. The resulting ESA sound waves are... 

In this method, quartz piezoelectric crystals with a fundamental frequency near 10 MHz are glued to a specimen with flat and parallel opposite faces (Fig. 1). With suitable electronics (Fig. 2), high-frequency, phase-coherent pulses are gated from a continuous carrier wave and applied to the quartz transducer, which both transmits pulses and receives reflected pulses. From the round-trip transit time, t (typically 5 tsec), and the specimen length, / (typically 1 to 2 cm), the sound velocity is z = ll/t. Elastic-stiffness constants are computed by C - where p is mass density. Different waves (longitudinal, transverse, extensional, torsional, etc.) are generated by various transducers, and are related to different elastic constants. 

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