The C–H stretch spectrum of methoxy adsorbed on Cu(100) has been measured using Fourier transform infrared spectroscopy. Fermi resonance coupling constants in methoxy are calculated using a normal mode model where the unperturbed modes were either experimentally determined or inferred from ab initio calculations performed for a methoxy-Mo model complex. The measured frequency shifts and intensity redistribution observed in the C–H stretch region are qualitatively reproduced by the calculations.

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Structural wellbore integrity is an important issue for a sustainable provision of geothermal energy. Raman scattering based fiber optic distributed temperature sensing (DTS) can help to monitor the status of a well and therefore help to optimize expensive work-over activities. This study reports on the installation of a fibre optic cable in the cemented annulus behind the anchor casing in the high temperature geothermal well HE-53, Hellisheiði geothermal field, SW Iceland. Although the cable has been damaged during the installation, temperature data could be acquired during the entire length of installation down to 261.3 m. Temperature measurements were performed during the installation in spring 2009, during the onset of a flow test in summer 2009 and after a 8.5 month shut-in period in summer 2010. During the flow test, maximum temperatures of 230• C were measured after two weeks fluid production. Using optical time domain reflectometry (OTDR), attenuation measurements at 850 and 1300 nm enabled to identify mechanical, thermal, and chemical degradation along the optical fibre. The observed degradation led to erroneous temperature readings and limits, due to the optical budget of the DTS system, the accessible length of the fibre. The characteristics and the influence of the different degradation mechanisms on the accuracy of the DTS measurements are discussed and recommendations for an optimized installation are given.

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