>>Electron Spin Resonance
>
> I don't see how that is related (ESR) any more
> than NMR would be ..... though NMR could probably
> detect some classes of explosives by the high Nitrogen
> content alone. Once you had the explosives in the equipment ...
> --
> Cliff
So...
According to Planck's law, electromagnetic radiation will be absorbed if:
(see complex formula)
Electromagnetic wave absorber ?? to weaken/smear signal as such cells will boost.
formatting link
[ The absorption of energy causes a transition from the lower energy state to the higher energy state. (See Figure 1.1) In conventional spectroscopy, n is varied or swept and the frequencies at which absorption occurs correspond to the energy differences of the states. (We shall see later that EPR differs slightly.) This record is called a spectrum. (See Figure 1.2) Typically, the frequencies vary from the megahertz range for NMR (Nuclear Magnetic Resonance) (AM, FM, and TV transmissions use electromagnetic radiation at these frequencies), through visible light, to ultraviolet light. Radiation in the gigahertz range (the same as in your microwave oven) is used for EPR experiments. ]
[ Because we can change the energy differences between the two spin states by varying the magnetic field strength, we have an alternative means to obtain spectra. We could apply a constant magnetic field and scan the frequency of the electromagnetic radiation as in conventional spectroscopy. Alternatively, we could keep the electromagnetic radiation frequency constant and scan the magnetic field. (See Figure 1.4) A peak in the absorption will occur when the magnetic field tunes the two spin states so that their energy difference matches the energy of the radiation. This field is called the field for resonance. Owing to the limitations of microwave electronics, the latter method offers superior performance. This technique is used in all Bruker EPR spectrometers. ]
John