- Email: [email protected]
Direct observation of a nucleation and growth process on an atomic scale
A101 394 SCANNING ELECTRON
Surface Science 181 (1987) 394-402 North-Holland, Amsterdam TUNNELING AND SCANNING TRANSMISSION MICROSCOPY OF BIOLOGICAL MEMBRANES
A. S T E M M E R ,
R. REICHELT,
A. ENGEL
M.E. Miiller-[nstitute for High-resolution Electron Microscopy at the Biozentrum of the University of Basel Klingelbergstrasse 70, CH-4056 Basel Switzerland J.P. R O S E N B U S C H
Department of Microbiology, Biozentrum of the University of Basel Klingelbergstrasse 70, CH-4056 Basel, Switzerland
M. RINGGER, H.R. H I D B E R
and H.-J. GONTHERODT
Physics Institute of the University of Basel, Klingelbergstrasse 82, CH-4056 Basel Switzerland Received 14 July 1986; accepted for publication 30 October 1986 The feasibility of imaging porin membrane, which is a reconstituted biological membrane consisting of phospholipid and protein, was studied by scanning tunneling microscopy (STM). Due to detailed knowledge of its composition from biochemical and its three-dimensional (3D) structure from electron microscopical analysis, porin vesicles seem to be a suitable model specimen for exploring the application of STM in biology. Unstained vesicles adsorbed onto a thin amorphous carbon film supported by a finder grid were localized using a scanning transmission electron microscope (STEM) at low irradiation doses ( < 100 e - / n m 2 ). Suitable areas of the sample were then positioned in the STM by a light optical telescope. STM images taken under ambient pressure from empty amorphous carbon films exhibited corrugations in the range of _<1 nm, whereas steps having a height of 5 nm were reproducibly observed on grids with porin vesicles. Since this value is in good agreement with that obtained from air-dried metal shadowed vesicles, we interpret these steps as the edges of porin membranes.
Surface Science 181 (1987) 4 0 3 - 4 1 1 North-Holland, Amsterdam
403
DIRECT OBSERVATION OF A NUCLEATION AND GROWTH PROCESS ON AN ATOMIC SCALE E. R I T T E R , R.J. BEHM *, G. P(3TSCHKE ** a n d J. W l N T T E R L I N lnstitut ffir Physikalische Chemie and lnstitut fiir Kristallographie **, Universitdt Miinchen, D-8000 Mfinchen 2, Fed. Rep. of Germany Received 15 September 1986;accepted for publication 25 November 1986 Scanning tunneling microscopy (STM) was used to follow the structural transformation from the dean, reconstructed Pt(100) surface into the adsorbate covered, bulk-like (1 × 1) phase. Direct observations confirm a "nucleation and growth" mechanism for this reaction. Homogeneous and heterogeneous nucleation are identified for different adsorbates, a mechanism is proposed to account for these differences. The growth of the (1 × 1) phase is shown to proceed anisotropicaUy, in strict correlation to the spatial orientation of the original reconstructed phase.
Surface Science 181 (1987) 394-402 North-Holland, Amsterdam TUNNELING AND SCANNING TRANSMISSION MICROSCOPY OF BIOLOGICAL MEMBRANES
A. S T E M M E R ,
R. REICHELT,
A. ENGEL
M.E. Miiller-[nstitute for High-resolution Electron Microscopy at the Biozentrum of the University of Basel Klingelbergstrasse 70, CH-4056 Basel Switzerland J.P. R O S E N B U S C H
Department of Microbiology, Biozentrum of the University of Basel Klingelbergstrasse 70, CH-4056 Basel, Switzerland
M. RINGGER, H.R. H I D B E R
and H.-J. GONTHERODT
Physics Institute of the University of Basel, Klingelbergstrasse 82, CH-4056 Basel Switzerland Received 14 July 1986; accepted for publication 30 October 1986 The feasibility of imaging porin membrane, which is a reconstituted biological membrane consisting of phospholipid and protein, was studied by scanning tunneling microscopy (STM). Due to detailed knowledge of its composition from biochemical and its three-dimensional (3D) structure from electron microscopical analysis, porin vesicles seem to be a suitable model specimen for exploring the application of STM in biology. Unstained vesicles adsorbed onto a thin amorphous carbon film supported by a finder grid were localized using a scanning transmission electron microscope (STEM) at low irradiation doses ( < 100 e - / n m 2 ). Suitable areas of the sample were then positioned in the STM by a light optical telescope. STM images taken under ambient pressure from empty amorphous carbon films exhibited corrugations in the range of _<1 nm, whereas steps having a height of 5 nm were reproducibly observed on grids with porin vesicles. Since this value is in good agreement with that obtained from air-dried metal shadowed vesicles, we interpret these steps as the edges of porin membranes.
Surface Science 181 (1987) 4 0 3 - 4 1 1 North-Holland, Amsterdam
403
DIRECT OBSERVATION OF A NUCLEATION AND GROWTH PROCESS ON AN ATOMIC SCALE E. R I T T E R , R.J. BEHM *, G. P(3TSCHKE ** a n d J. W l N T T E R L I N lnstitut ffir Physikalische Chemie and lnstitut fiir Kristallographie **, Universitdt Miinchen, D-8000 Mfinchen 2, Fed. Rep. of Germany Received 15 September 1986;accepted for publication 25 November 1986 Scanning tunneling microscopy (STM) was used to follow the structural transformation from the dean, reconstructed Pt(100) surface into the adsorbate covered, bulk-like (1 × 1) phase. Direct observations confirm a "nucleation and growth" mechanism for this reaction. Homogeneous and heterogeneous nucleation are identified for different adsorbates, a mechanism is proposed to account for these differences. The growth of the (1 × 1) phase is shown to proceed anisotropicaUy, in strict correlation to the spatial orientation of the original reconstructed phase.