Radiofrequency region

In NMR spectroscopy the precise energy differences between such nuclear magnetic states are of interest. To measure these differences, electromagnetic waves in the radiofrequency region (1-600 MHz) are applied, and the frequency at which transitions occur between the states, is measured. At resonance the condition... 

Most of us have encountered nuclear magnetic resonance (NMR) spectroscopy many times in the past, for example when analysing the products of preparative organic chemistry. In NMR spectroscopy, the nucleus of an atom is excited following absorption of a photon (in the radiofrequency region of the electromagnetic spectrum). 

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

Radiotelescopes are used to scan the universe for radiation in the radiofrequency region of the spectrum (see Figure 3.1). As illustrated in Figure 5.11 such a telescope consists of a parabolic reflecting dish which focuses all parallel rays reaching it onto a radiofrequency detector supported at the focus of the paraboloid. The surface of such a dish must be constructed accurately but only sufficiently so that the irregularities are small compared with the wavelength of the radiation, which is of the order of 0.5 m. 

RF radiation (Section 14.1A) Radiation in the radiofrequency region of the electromagnetic spectrum, characterized by long wavelength and low frequency and energy. 

H and 13C nuclei are the most commonly observed nuclei, but because they absorb in different radiofrequency regions, they cannot be observed at the same time (i.e. in the H NMR spectrum, 13C signals are not observed). 

On our planet, we live at the bottom of an ocean if air. The two "windows" of air for electromagnetic radiations are in the visible and radiofrequency regions. The former window has been used by living organisms since immemorial times, but the latter window has only recently allowed mankind to obtain information on our universe. The discovery by radioastronomic means of quasars, pulsars and (most relevant for the present discussion) polyacetylenic nitriles and dinitriles indicates that carbon-containing cages and chains are ubiquitous in the cosmos. 

A rather small fraction of the cosmic radiation consists of electromagnetic radiation and electrons. The former vary in energy from a small percentage of y-rays to a considerable intensity of X-rays, to visible light and to radiation in the radiofrequency region. The types... 

According to Equation 1, an ensemble of ions of differing masses will have a spectrum of cyclotron frequencies which is characteristic of that ensemble. For a magnetic field strength of 1 tesla and a mass range of 15 amu to 1500 amu, the cyclotron frequency spectrun (Equation 1) extends from 10 kHz to 1 MHz and thus falls in the radiofrequency region of the electromagnetic spectrum. 

---