Scanning probe microscopy with 'chemical sensitivity'

We discuss recent developments in scanning probe microscopy aiming to combine ultra-high lateral resolution with the potential of “chemical sensitivity”. Particular attention is given to techniques beyond the well-established scanning tunneling microscopy (STM) and atomic force microscopy (AFM), which allow surface imaging with atomic resolution, however, do hardly allow chemical identification of the structures under study. Starting with “nanomechanical” imaging using a modified AFM capable of local friction and elasticity measurements, we demonstrate that scanning probe microscopy can well be combined with a kind of materials recognition capability. We then turn to scanning near-field optical microscopy and spectroscopy (SNOM), a technique that combines high lateral resolution with nearly all the information accessible by optical techniques. In both cases, the present spatial resolution limits are discussed