The large fragment of E.coli DNA polymerase I is imaged by scanning tunneling microscope. The specimen is deposited on highly oriented pyrolytic graphite surface, and then covered with pure paraffin oil in order to ma...The large fragment of E.coli DNA polymerase I is imaged by scanning tunneling microscope. The specimen is deposited on highly oriented pyrolytic graphite surface, and then covered with pure paraffin oil in order to maintain hydration of the molecules. Images of the enzyme reveal an ellipsoid shape of 5.5-6.0nm wide and 7.0 -7.5 nm long. The conformation of the enzyme is in agreement with the model derived from X- ray crystallography studies.展开更多
Uncoated DNA deposited on graphite surface was imaged in air with the scanning tunneling microscope (STM). The images revealed a helical pitch of 3.6 nm whereas the average width was 2.3nm. Periodic alternation of maj...Uncoated DNA deposited on graphite surface was imaged in air with the scanning tunneling microscope (STM). The images revealed a helical pitch of 3.6 nm whereas the average width was 2.3nm. Periodic alternation of major and minor grooves were resolved with high resolution. Our STM images were in reasonable agreement with the B-form DNA structural model derived from X-ray diffraction studies. It was concluded that the STM could be useful for local structural studies of biomolecules.展开更多
A UHV system specially designed for studying surface and interface atomic structure by MeV ion scattering and channeling is described. The vacuum in the UHV chamber is 133.332×10-10Pa. The chamber is equipped wit...A UHV system specially designed for studying surface and interface atomic structure by MeV ion scattering and channeling is described. The vacuum in the UHV chamber is 133.332×10-10Pa. The chamber is equipped with an ion gun used for sample cleaning, a translatable four-grid LEED-Auger system used for characterization of the crystal surface, and a three dimensional goniometer. The crystal preparation and cleaning procedure of Al(100) are presented. The surface peak intensity of Al(100)-【100】 and Al(100)- 【100】 has been measured by MeV ion channeling and scattering. The measured surface peak intensity was compared with that of Monte-Carlo simulation. The experimental results indicate that the thermal vibration amplitude of Al(100) surface atoms is 1.2 -1.3 times that of bulk atoms. The relaxation of first layer for Al(100) is less than -0.005nm.展开更多
High energy ion backscattering can be used to enhance the sensitivity of oxygen analysis. At He++ ion energy of 8.8 MeV, the yield due to oxygen is about 25 times larger than that predicted by Rutherford formula. The ...High energy ion backscattering can be used to enhance the sensitivity of oxygen analysis. At He++ ion energy of 8.8 MeV, the yield due to oxygen is about 25 times larger than that predicted by Rutherford formula. The elemental stoichiometry of some bulk and thin film superconductor samples was determined. The details of the measuring method are discribed.展开更多
文摘The large fragment of E.coli DNA polymerase I is imaged by scanning tunneling microscope. The specimen is deposited on highly oriented pyrolytic graphite surface, and then covered with pure paraffin oil in order to maintain hydration of the molecules. Images of the enzyme reveal an ellipsoid shape of 5.5-6.0nm wide and 7.0 -7.5 nm long. The conformation of the enzyme is in agreement with the model derived from X- ray crystallography studies.
文摘Uncoated DNA deposited on graphite surface was imaged in air with the scanning tunneling microscope (STM). The images revealed a helical pitch of 3.6 nm whereas the average width was 2.3nm. Periodic alternation of major and minor grooves were resolved with high resolution. Our STM images were in reasonable agreement with the B-form DNA structural model derived from X-ray diffraction studies. It was concluded that the STM could be useful for local structural studies of biomolecules.
文摘A UHV system specially designed for studying surface and interface atomic structure by MeV ion scattering and channeling is described. The vacuum in the UHV chamber is 133.332×10-10Pa. The chamber is equipped with an ion gun used for sample cleaning, a translatable four-grid LEED-Auger system used for characterization of the crystal surface, and a three dimensional goniometer. The crystal preparation and cleaning procedure of Al(100) are presented. The surface peak intensity of Al(100)-【100】 and Al(100)- 【100】 has been measured by MeV ion channeling and scattering. The measured surface peak intensity was compared with that of Monte-Carlo simulation. The experimental results indicate that the thermal vibration amplitude of Al(100) surface atoms is 1.2 -1.3 times that of bulk atoms. The relaxation of first layer for Al(100) is less than -0.005nm.
文摘High energy ion backscattering can be used to enhance the sensitivity of oxygen analysis. At He++ ion energy of 8.8 MeV, the yield due to oxygen is about 25 times larger than that predicted by Rutherford formula. The elemental stoichiometry of some bulk and thin film superconductor samples was determined. The details of the measuring method are discribed.
