The electronic properties of hydrogen- and oxygen-terminated diamond surfaces exposed to the air are investigated by scanning probe microscopy （SPM）. The results indicate that for the hydrogen-terminated diamond sur...The electronic properties of hydrogen- and oxygen-terminated diamond surfaces exposed to the air are investigated by scanning probe microscopy （SPM）. The results indicate that for the hydrogen-terminated diamond surface a shallow acceptor above the valence-band-maximum （VBM） appears in the band gap. However, the oxygen-terminated diamond film exhibits a high resistivity with a wide band gap. Based on the density-functional-theory, the densities of states, corresponding to molecular adsorbate in hydrogenated and oxygenated diamond （100） surfaces, are studied. The results show that the shallow acceptor in the band gap for the hydrogen-terminated diamond film can be attributed to the interaction between the surface C H bonding orbitals and the adsorbate molecules, while for the oxygen-terminated diamond film, the interaction between the surface C-O bonding orbitals and the adsorbate molecules can induce occupied states in the valence-band.展开更多
The films of octadecene, dodecene, and undecenoic acid were prepared on H-terminated Si surface in the presence of ultraviolet irradiation. The resulted films were characterized with water-contact angle measurement an...The films of octadecene, dodecene, and undecenoic acid were prepared on H-terminated Si surface in the presence of ultraviolet irradiation. The resulted films were characterized with water-contact angle measurement and infrared spectroscopy. The friction-reducing behavior of the prepared films was examined on a static-dynamic friction coefficient measurement apparatus and on an atomic force microscope. It was found that all the reacted films on the Si substrate showed good friction-reducing ability; especially, the film of the octadecene exhibited the best friction-reducing ability. This was attributed to the transfer of the reacted films onto the counter face with formation of a transfer film on the counterpart surface, which led to the transformation of the sliding between the reacted films and the hard ceramic to fiat between the reacted films and its transfer film on the counterpart surface. The macroscopic and microscopic friction behaviors of the prepared films were dependent on their molecular chain lengths. Thus the octadecene reacted film with the highest degree of ordering arrangement showed the best friction-reducing and antiwear abilities in sliding against Si3N4.展开更多
Development of novel functional devices has been expected by modification for Si surface. This study investigated immobilization and roles of the Si surface with flowing surfactant by in situ ATR-FTIR method. This res...Development of novel functional devices has been expected by modification for Si surface. This study investigated immobilization and roles of the Si surface with flowing surfactant by in situ ATR-FTIR method. This result suggested that the surfactant prevented oxidation of the hydrogen-terminated Si surface from the higher concentration in aqueous solution. These would guard the Si surface against H2O molecules.展开更多
基金supported by the National Natural Science Foundation of China(Grant No 50675112)National Basic Research Program of China(Grant No 2007CB707702)the China Postdoctoral Science Foundation(Grant No 20070410515)
文摘The electronic properties of hydrogen- and oxygen-terminated diamond surfaces exposed to the air are investigated by scanning probe microscopy （SPM）. The results indicate that for the hydrogen-terminated diamond surface a shallow acceptor above the valence-band-maximum （VBM） appears in the band gap. However, the oxygen-terminated diamond film exhibits a high resistivity with a wide band gap. Based on the density-functional-theory, the densities of states, corresponding to molecular adsorbate in hydrogenated and oxygenated diamond （100） surfaces, are studied. The results show that the shallow acceptor in the band gap for the hydrogen-terminated diamond film can be attributed to the interaction between the surface C H bonding orbitals and the adsorbate molecules, while for the oxygen-terminated diamond film, the interaction between the surface C-O bonding orbitals and the adsorbate molecules can induce occupied states in the valence-band.
基金National Natural Science Foundation of China(Grant No.50023001).
文摘The films of octadecene, dodecene, and undecenoic acid were prepared on H-terminated Si surface in the presence of ultraviolet irradiation. The resulted films were characterized with water-contact angle measurement and infrared spectroscopy. The friction-reducing behavior of the prepared films was examined on a static-dynamic friction coefficient measurement apparatus and on an atomic force microscope. It was found that all the reacted films on the Si substrate showed good friction-reducing ability; especially, the film of the octadecene exhibited the best friction-reducing ability. This was attributed to the transfer of the reacted films onto the counter face with formation of a transfer film on the counterpart surface, which led to the transformation of the sliding between the reacted films and the hard ceramic to fiat between the reacted films and its transfer film on the counterpart surface. The macroscopic and microscopic friction behaviors of the prepared films were dependent on their molecular chain lengths. Thus the octadecene reacted film with the highest degree of ordering arrangement showed the best friction-reducing and antiwear abilities in sliding against Si3N4.
文摘Development of novel functional devices has been expected by modification for Si surface. This study investigated immobilization and roles of the Si surface with flowing surfactant by in situ ATR-FTIR method. This result suggested that the surfactant prevented oxidation of the hydrogen-terminated Si surface from the higher concentration in aqueous solution. These would guard the Si surface against H2O molecules.
