The purpose of this proposal is to test the idea that the puzzling variations in the behaviour of carbon nanotubes under high pressure observed by different research groups around the world are due to Raman resonance effects. The implication is that high-pressure Raman spectroscopy of nanotubes - and indeed the study of nanotubes in different solvents - absolutely requires tunable laser excitation, so the same nanotubes (diameter and chirality) can be picked out as the conditions are changed. This would bring high-pressure Raman to a much higher degree of precision and here enable reliable and definitive high-pressure data to be obtained for single wall carbon nanotubes. As far as we are aware, no laboratory world-wide has the capabilities (tunable Raman plus high pressure) required for this programme, so the apparatus will constitute a novel, indeed unique facility. The results of this programme will have pivotal implications for the entire literature on the subject. The results will provide means of reliable testing of mechanical response of carbon nanotubes to applied stress and will provide decisive insights into interplay (and connection) between mechanical and electronic properties of nanotubes. This will provide vital information to the academic community and to workers in nanotechnology exploiting carbon nanothubes.