Radiofrequency excitation

Q. What are the advantages of radiofrequency-excited electrodeless discharge lamps ... 

Fig. 1. One-dimensional SPI sequence. Note the broadband radiofrequency pulse applied in the presence of the phase encode gradient A-space is sampled, point by point, by amplitude cycling the phase encode gradient with repetitive radiofrequency excitation pulses. The encoding time is tp, the repetition time is TR. After Balcom.

Early quadrupole nutation experiments concerned the chemical status of nonframework A1 in dealuminated zeolite Y of static samples or with MAS at moderate rates [137-139,154). However, it has been shown that Al quadrupole nutation with fast (12.5 kHz) MAS and radiofrequency excitation fields up to 220 kHz provides significantly better spectral resolution [155), enabling, for example, the resonances at 0, 30, 56, and 62 ppm observed in ultrastable zeolite Y to be assigned to different aluminous species. The various quadrupolar para-... 

Electrodeless discharge lamps EDLs employ either microwave energy (microwave-excited EDLs) or radiofrequency energy (radiofrequency-excited EDLs)... 

T. Busch et alP have developed a technique to improve the efficiency and flexibility of acquisitions of multiple voxels in MRS imaging (MRSI) by combining two-dimensional-selective radiofrequency excitations and... 

In order to handle efficiently the large number of experiments carried out by laser-microwave spectroscopy and to illustrate the techniques and their differences as compared to work utilizing, e.g., pure laser or pure radiofrequency excitation, the organization of this chapter is by experimental methods rather than by the physical goals pursued in the different experiments. Typical examples will be described in some detail, and reference to other or related work is made. However, the list of references may not be complete. 

The Av = 1 bands of NH were also observed and analyzed in the high-resolution (0.005 cm" ) FT IR emission spectrum of a radiofrequency-excited N2 + SiH4 plasma the measurements are an improvement over the data of [8] and give new information, especially for the region above 3500 cm results have not yet been published [9]. 

Electrodeless discharge lamps are used less frequently than the hollow-cathode lamps except for analytes such as arsenic and selenium. These lamps may be excited using either microwave energy (although these tend to be less stable) or radiofrequency energy. The radiofrequency-excited lamps are less... 

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