Spectroscopic scanning near-field optical microscopy with a free electron laser: CH2 bond imaging in diamond films

Hydrogen chemistry in thin films and biological systems is one of the most difficult experimental problems in today's science and technology We succes sfully tested a novel solution, based on the spectroscopic version of scann ing near-field optical microscopy (SNOM). The tunable infrared radiation of the Vanderbilt free electron laser enabled us to reveal clearly hydrogen-d ecorated grain boundaries on nominally hydrogen-free diamond films. The ima ges were obtained by SNOM detection of reflected 3.5 mum photons, correspon ding to the C-H stretch absorption, and reached a lateral resolution of 0.2 mum, well below the lambda /2 (lambda = wavelength) limit of classical mic roscopy.