Radio-frequency region

Fourier transform spectroscopy in the radio frequency region has been applied most importantly in pulsed Fourier transform NMR spectroscopy, which is not a subject which... 

Radiation with long wavelengths falls in the infrared, microwave, or radio frequency regions. Heat lamps make use of infrared radiation, microwave ovens cook with microwave radiation, and radio and television signals are transmitted by radio waves. 

Absorption of electromagnetic radiation in the radio-frequency region of the spectrum resulting in changes in the orientation of spinning nuclei in a magnetic field. 

Fig. 14. Energy levels of the free radical CN showing the observed optical and radio transition. The violet band is observed against Ophiuchi (Thaddeus and Clauser, 1966) and the radio frequency transitions are measured in the Orion nebula (Jefferts et al., 1970). In the interstellar optical spectra quadrupole hyperfine and spin-doubling structure are entirely unresolved and therefore the rotational levels can be approximated as though the electronic states were However, these splittings are partly resolved in the radio frequency region but we note that only one component of the spin doublet has been observed...

It is this absorption of electromagnetic energy that is measured in NQR spectroscopy. Radiation in the radio-frequency region is actually employed to effect transitions among the various orientations of a quadru-polar nucleus in a nonspherical field. In the experiment, which is generally carried out on a powder sample, one set of resonances is exposed for each chemically or crystallographically inequivalent quadrupolar nucleus... 

Nuclear magnetic resonance (NMR) spectroscopy is based on the measurement of absorption of electromagnetic radiation in the radio-frequency region of roi hly 4 to 900 MHz. In contrast to Uy, visible, andlR absorption, nuclei of atoms rather than outer electrons are involved in the absorption process. Furthermore, to cause nuclei to develop the energy states required for absorption to occur, it is necessary to place the analyte in an intense magnetic field. In this chapter we describe the theory, instrumentation, and applications cfhiMR spectroscopy. 

NMR is basically another form of absorption spectrometry that can be used in addition to IR, or UV, spectrometries. It is based on the absorption of electromagnetic radiation under appropriate conditions in the radio-frequency region at frequencies defined by the nature of the sample. Absorption is a function of each nucleus in the molecule. The main purpose of this technique is to provide information for the identification of organic molecules by studying the magnetic properties of nuclei. 

From dielectric studies in the radio frequency region, it has long been known that PAA is negatively anisotropic, i.e., = ,—< 0. However,... 

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