We report an adjustable, oxide-free tunnel junction for inelastic electron tunneling spectroscopy that is capable of detecting the vibrational modes of molecules adsorbed on clean metal surfaces. In this article, we describe the details of these junctions and the procedure by which the tunneling data is obtained and analyzed. We also describe a compact 4He cryostat that was built to test the properties of these junctions. The performance of the junctions is demonstrated with tunneling data taken with a neon - hydrogen film adsorbed on platinum.
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