Surface investigation of carbon films: from diamond to graphite

In the present work, a detailed spectroscopic investigation of carbon in different crystalline forms from diamond to graphite was carried out. The spectra of photoemission peak, plasmon losses and X-rays-excited C KLL were studied in order to characterize the carbon phase in different samples. In addition, a method for determination of sp(2)/sp(3) ratio from the first derivative of Auger C KLL spectrum was employed. The obtained results indicated that carbon photoemission peak for sp(2) and sp(3) configurations is characterized by the same value of binding energy. The peaks of plasmon losses and Auger KLL transition were more diagnostic than C 1s photoemission peak, permitting to distinguish the sp(2) and sp(3) configurations. For intermediate situation, which is present in diamond-like carbon (DLC), characterized by a mixture of sp(2) and sp(3) states, the spectra were very similar to the carbon-black, whereas single-wall carbon nanotubes (CNT) were containing about 50% sp(2) states.