Ultrahigh-vacuum spectroscopy, effect

Correlations of in situ and ex situ observations. The characterization methods of surface science have already been established within an electrochemical context, because they can provide structural definition of fine distance scales as well as atomic composition of a surface and, sometimes, vibrational spectroscopy of adsorbates. These ex situ methods normally involve transfer of an electrode from the electrochemical environment to ultrahigh vacuum, and the degree to which they provide accurate information about structure and composition in situ is continuously debated. Additional work is needed to clarify the effect of emersion of samples and their transfer to ex situ measurement environments. The most appropriate experimental course requires observations by techniques that can be employed in both environments. Vibrational spectroscopy, ellipsometry, radiochemical measurements, and x-ray methods seem appropriate to the task. Once techniques suited to this problem are established, emphasis should be placed on the refinement of transfer methods so that the possibilities for surface reconstruction and other alterations in interfacial character are minimized. 

In situ analysis is performed inside the tribometer, which incorporates the surface probe. This mode allows exploration of the friction and adhesion of clean solid surfaces, the effect of adsorbed species or the nature of the lubricant phase, in order to elucidate the triboinduced surface modifications in as direct a manner as possible. Depending on the analytical technique used, the nature of the environment during the tribotest is not necessarily the same as that during analysis in situ Raman spectroscopy can be performed in ambient air, whereas in situ XPS and AES require ultrahigh vacuum. This mode can be performed in either of two configurations according to the time-scale criterion. 

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