Magnet requirements

A short transfer line (<30 cm) from the SPE unit to the flow probe, so minimising broadening of the eluted anal3de peak. Such short transfer lines are only practical with shielded magnets since unshielded magnets require a minimum length of 2 m [46]. 

The design of molecule-based magnets requires the assembly of magnetic bricks in a controlled fashion. The bricks we play with are characterized by three factors, namely shape, chemical functionality, and spin distribution. The first two factors are common to all bricks (or building blocks) used in molecular chemistry. The third is specific to molecular magnetism. Spin distribution is a new dimension. Let us consider the brick [Cu(opba)]2- (where opba stands for ortho-pheny-lenebis(oxamato)) this is shown below as a typical example [6, 7]. 

The production of samarium cobalt magnets requires lhe use of calcium. The reaction is... 

Selected topics in Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry instrumentation are discussed in depth, and numerous analytical application examples are given. In particular, optimization ofthe single-cell FTMS design and some of its analytical applications, like pulsed-valve Cl and CID, static SIMS, and ion clustering reactions are described. Magnet requirements and the software used in advanced FTICR mass spectrometers are considered. Implementation and advantages of an external differentially-pumped ion source for LD, GC/MS, liquid SIMS, FAB and LC/MS are discussed in detail, and an attempt is made to anticipate future developments in FTMS instrumentation. 

The power supply for the magnets requires a direct-current capacity of about 1000 amps at 300-800 volts—similar to that used to power elevators. But the ones for calutron magnets must also be regulated precisely to produce a stable magnetic field. 

Complete interconversion of in-phase and anti-phase magnetization requires a delay such that 7i/rJ = Tz/li.e. a delay of 1/(2J12). A delay of 1/J12 causes in-phase magnetization to change its sign ... 

From this it is easy to see that complete conversion to anti-phase magnetization requires 2 712t= tt/2 i.e. r= 1/(4 Ju). 

Because each kind of nucleus has its own gyromagnetic ratio, different energies are required to bring different kinds of nuclei into resonance. For example, an NMR spectrometer with a magnet requiring a frequency of 300 MHz to flip the spin of an H nucleus requires a frequency of 75 MHz to flip the spin of a C nucleus. NMR spectrometers are equipped with radiation sources that can be tuned to different frequencies so that they can be used to obtain NMR spectra of different kinds of nuclei... 

We will not discuss here the details of the instrument. Both the electronic circuitry and the magnet require a very high-level technology to produce. For example, the magnetic field must be uniform over the sample to within 1 part in 10 that was not easily achieved in the past, but is now routine. 

Based on these magnetic requirements, it is obvious that an external magnetic field can change the ISC rate... 

The yield strength of 99.999 + % A1 with RRR = 3700 at low temperature is between 5.5 and 8.3 MN/m. The corresponding strain level is 0.0001 to 0.00017, at which point aluminum becomes elastoplastic with a small tangent modulus of approximately 13.8 Mn/m. The high strains of 0.003 and high triaxial stresses, unavoidable in large magnets, require complete aluminum confinement to avoid excessive plastic flow [%... 

Unlike optical detection, integrated electrical detectors (impedimetric, electrochemical, most mechanical and thermal, certain magnetic) require electrode interconnections and on-chip electrical traces (conductive pathways) to connect to external electronics. Although this is an added complication, it is typically easier to implement than full monolithic integratiOTi of an optical excitation-and-detection system. 

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