Electromagnetic radiation magnetic field

Temperature Ionic strength Solvents Electromagnetic radiation (UV, light) Electric fields Mechanical stress, strain Sonic radiation Magnetic fields pH Specific ions Chemical agents Enzyme substrates Affinity ligands Other biochemical agents... 

To this point, we have considered only the radiation field. We now turn to the interaction between the matter and the field. According to classical electromagnetic theory, the force on a particle with charge e due to the electric and magnetic fields is... 

MW frequency of 10 Hz. There are various considerations that influence the choice of the radiation frequency. Higher frequencies, which require higher magnetic fields, give inlierently greater sensitivity by virtue of a more favourable Boltzmaim factor (see equation (b 1.15.11)). However, several factors place limits on the frequency employed, so that frequencies in the MW region of the electromagnetic spectrum remain favoured. One limitation is the sample size at frequencies around 40 GHz the dimensions of a typical... 

Plane-polarized electromagnetic radiation showing the electric field, the magnetic field, and the direction of propagation. 

The interaction of electromagnetic radiation with matter can be explained using either the electric field or the magnetic field. For this reason, only the electric field component is shown in Figure 10.2. The oscillating electric field is described by a sine wave of the form... 

In absorption spectroscopy a beam of electromagnetic radiation passes through a sample. Much of the radiation is transmitted without a loss in intensity. At selected frequencies, however, the radiation s intensity is attenuated. This process of attenuation is called absorption. Two general requirements must be met if an analyte is to absorb electromagnetic radiation. The first requirement is that there must be a mechanism by which the radiation s electric field or magnetic field interacts with the analyte. For ultraviolet and visible radiation, this interaction involves the electronic energy of valence electrons. A chemical bond s vibrational energy is altered by the absorbance of infrared radiation. A more detailed treatment of this interaction, and its importance in deter-... 

FIGURE A.9 An electromagnetic field oscillates in time and space. The magnetic field is perpendicular to the electric field. The length ot an arrow at any point represents the strength of the field at that point, and its orientation denotes its direction. Both fields are perpendicular to the direction of travel of the radiation. 

The aurora borealis, a spectacular atmospheric light show shown in Figure 7-25. originates in the thermosphere. In addition to electromagnetic radiation, the sun emits a steady stream of protons and electrons. The Earth s magnetic field deflects most of these particles, but some reach the thermosphere above the north and south poles of the... 

Overview. Electrons orbiting in a magnetic field lose energy continually in the form of electromagnetic radiation (photons) emitted tangentially from the orbit. This light is called synchrotron radiation. The first dedicated synchrotron light source was the Stanford Synchrotron Radiation Laboratory (SSRL) (1977). Nowadays, many... 

The basic features of an epr spectrometer are shown in Figure 2.95. The microwave source is a Klystron tube that emits radiation of frequency determined by the voltage across the tube. Magnetic fields of 0.1 — 1 T can be routinely obtained without complicated equipment and are generated by an electromagnet. The field is usually modulated at a frequency of 100kHz and the corresponding in-phase component of the absorption monitored via a phase-sensitive lock-in detector. This minimises noise and enhances the sensitivity of the technique. It is responsible for the distinctive derivative nature of epr spectra. Thus, the spectrum is obtained as a plot of dA/dB vs. 

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