The construction of a compact high pressure unit for UV-VIS-NIR spectroscopic measurements at pressures up to 400 MPa is described. The pressure generating system can be operated with different pressure liquids, depending on the spectral characteristics required for specific applications. The system can be used for thermodynamic as well as a variety of kinetic measurements.

The development of a high-pressure nuclear magnetic resonance (NMR) probe designed for a 400 MHz narrow bore NMR spectrometer is reported. As for the earlier constructed system for wide bore magnets, the electrical leads of the radio frequency (rf) circuit, the tubes for the thermostating and high-pressure transmitting fluids, as well as the connections for the temperature control unit are all fitted through the bottom of the high-pressure vessel. The sample can easily be removed and rapidly exchanged through a top plug in the vessel. There is no need to modify the magnet in order to perform the high-pressure experiments. In comparison to the already published wide bore design, the spectral resolution could be improved to be better than 6 ϫ 10 −9 by selecting a different titanium alloy and a more symmetrical design. The high-pressure vessel and the rf circuit are placed in an aluminum jacket which has the same outer dimensions as a commercial narrow bore probe and can be fitted into the magnet in the same way.