Spectrometer magnetic flux density

For determination of the energy of a particles and for identification of a-emitting radionuclides, a. spectrometers are usually applied, having been calibrated by use of a emitters of known energy. Relatively exact determination of the energy of a particles, protons and deuterons can be made by means of a magnetic spectrometer. The relation between the velocity r of the particles, the magnetic flux density B and the radius r of the particles is... 

All NMR spectra were measured at Spectral Service GmbH, Cologne, Germany, on an NMR Spectrometer AC-P 300 (Bruker, Karlsruhe, Germany) equipped with automated sample changer and QNP-head for nuclei H, and P. Magnetic flux density is 7.05 T proton... 

Magnetic spectrometers are based on Eq. (50.38) in Chap. 50, Vol. 5, stating that a charged particle moving perpendicularly to the magnetic flux density B will follow a circular path, the radius of which is proportional to the momentum of the particle... 

Chemical shift relates the Larmor frequency of a nuclear spin to its chemical environment l 3. The Larmor frequency is the precession frequency v0 of a nuclear spin in a static magnetic field (Fig. 1.1). This frequency is proportional to the flux density Bo of the magnetic field (v0 B0 = const.) 3. It is convenient to reference the chemical shift to a standard such as tetramethylsilane [TMS, (C//j)4Si] rather than to the proton ft. Thus, a frequency difference (Hz) is measured for a proton or a carbon-13 nucleus of a sample from the H or 13C resonance of TMS. This value is divided by the absolute value of the Larmor frequency of the standard (e.g. 400 MHz for the protons and 100 MHz for the carbon-13 nuclei of TMS when using a 400 MHz spectrometer), which itself is proportional to the strength B0 of the magnetic field. The chemical shift is therefore given in parts per million (ppm, 5 scale, SH for protons, 5C for carbon-13 nuclei), because a frequency difference in Hz is divided by a frequency in MHz, these values being in a proportion of 1 106. 

The maximum energy of radiation can be determined by plotting an absorption curve as shown in Fig. 6.7, or, more accurately, by use of a magnetic spectrometer, as in the case of a particles, but at much lower flux density B, because of the higher e/m values. At the same energy, the velocity v of electrons is much higher than that of a particles which makes relativistic correction necessary ... 

An alternative method of filtering is based on the use of a magnetic field. Magnetic mass spectrometers were developed and improved by the fathers of mass spectrometry, Thompson, Aston, and Bainbridge, in the early part of the twentieth century. An ion with velocity v travelling in a perpendicular magnetic field of flux density B will follow a circular trajectory of radius r. 

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