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picture1_Achew2


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File: Achew2
how it works invented in 1986 cantilever tip surface laser multi segment photodetector figure 4 three common types of afm tip a normal tip 3 m tall b supertip c ...

icon picture PPT Filetype Power Point PPT | Posted on 09 Sep 2022 | 3 years ago
Partial capture of text on file.
                           How It Works
                                     •   Invented in 1986
                                     •   Cantilever
                                     •   Tip
                                     •   Surface
                                     •   Laser 
                                     •   Multi-segment photodetector
                                      Figure 4. Three common types of AFM tip. (a) normal tip (3 µm tall); (b) 
                                      supertip; (c) Ultralever (also 3 µm tall). Electron micrographs by Jean-
                                      Paul Revel, Caltech. Tips from Park Scientific Instruments; supertip 
                                      made by Jean-Paul Revel.
                                          
                                       http://stm2.nrl.navy.mil/how-afm/how-afm.html#imaging%20modes
     http://www.molec.com/what_is_afm.html
                        Topography
   • Contact Mode
       – High resolution
       – Damage to sample
       – Can measure 
         frictional forces
   • Non-Contact Mode
       – Lower resolution
       – No damage to 
         sample
   • Tapping Mode
       – Better resolution     2.5 x 2.5 nm simultaneous topographic and friction image of highly 
                               oriented pyrolytic graphic (HOPG). The bumps represent the 
       –                       topographic atomic corrugation, while the coloring reflects the lateral 
         Minimal damage to  forces on the tip. The scan direction was right to left
         sample               http://stm2.nrl.navy.mil/how-afm/how-afm.html#imaging%20modes
                                   
                         Approach
      • In the approach the tip is not yet in contact 
         with the surface
      • Attractive forces maybe
      • Repulsive forces definitely 
         – Due to contact
         – Gives information about the elasticity or stiffness 
           of sample
                                  
                     Retraction
     • Attractive forces again during the 
       retraction phase 
        –Chemical and/or electrostatic
     • Break of attractive forces due to 
       retraction of the tip > characteristic 
       “jump” in force curve
                              
                           
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...How it works invented in cantilever tip surface laser multi segment photodetector figure three common types of afm a normal m tall b supertip c ultralever also electron micrographs by jean paul revel caltech tips from park scientific instruments made http stm nrl navy mil html imaging modes www molec com what is topography contact mode high resolution damage to sample can measure frictional forces non lower no tapping better x nm simultaneous topographic and friction image highly oriented pyrolytic graphic hopg the bumps represent atomic corrugation while coloring reflects lateral minimal on scan direction was right left approach not yet with attractive maybe repulsive definitely due gives information about elasticity or stiffness retraction again during phase chemical electrostatic break characteristic jump force curve...

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