Choosing the optimal technique

The resolution ( 1—2% ) is relatively poor because the incident energy is large. Note that the difference between the spectra is the result of the different g-values that are used, it is not the difference in resolution of the instruments, it is the access to lower Q that is crucial. In fact, across most of the energy transfer range the resolution of TOSCA is comparable or superior to that of MARI but the trajectory in (Q,co) means that above 1500 cm it is rare that it can be exploited. 

Clearly both types of instruments are highly complementary and both have strengths and weaknesses. Ideally, the same sample would be run first on an indirect geometry instrument which would provide a rapid, but still fairly detailed overview of the subject. In many instances this would be sufficient. Subsequent measurements on a direct geometry instrument would allow detailed aspects of the spectroscopy to be probed. Table 3.2 gives a list of INS (excluding triple axis) spectrometers that have recently been in operation, are in operation, or are planned. 

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