Department of Chemical Engineering, Texas Tech University, Lubbock, TexasWelcome to Greg McKenna's 'Polymers and Condensed Matter Physics Group'

Gregory B. McKenna
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Department of Chemical Engineering


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Atomic Force Microscope (AFM) - model PicoSPM from Molecular Imaging



  • X-Y range :25 microns with a resolution of better than  4 nanometers.

  • Z range: 7 microns with a resolution of 0.1 nanometers.

  • Operation mode : Contact mode : gives surface topography.

Magnet AC (MAC) mode (‘tapping’ mode) : The tip is driven at it’ resonance frequency by an electromagnet. In addition to topography the relative stiffness of the surface can be measured. Also, if the tip is chemically active then the strength of interaction between the surface and the active species on the tip can be measured.

Acoustic AC mode : similar to MAC mode, though the tip is driven at its resonance frequency by the Z-piezo.

  • Sample Stages :

Heating stage to 200 °C

Cooling (Pelitier) stage to -30 °C

A fluid cell for imaging under a range of liquids.

An EC cell for electrochemically controlled experiments.

In addition, we have built a temperature controlled pressure cell which is used for studying the inflation of nanometer thick polymer membranes.

The system also comes with an environmental chamber for studies under inert gas or controlled humidity conditions and a CleanLoad Glovebox for loading and unloading under clean room conditions. Finally, the scanner is mounted in a vibration isolation chamber to reduce ambient noise.

Experimental application

1. Rheological measurements of the thermoviscoelastic response of ultrathin polymer films

2. Rheological Property Determination at Surfaces and at the Nanoscale by Nano and Microsphere Embedding

Related Publications

1. O’Connell P.A. and McKenna G.B. “Rheological Measurements of the Thermoviscoelastic Response of

Ultrathin Polymer Films”, Science, Vol. 307, No. 5716, 1760-1763 (2005).


2. S. A. Hutcheson and G. B. McKenna, “Nanosphere Embedding into Polymer Surfaces: A Viscoelastic

 Contact Mechanics Analysis,”  Physical Review Letters, 94, 076103 (2005).

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Atomic Force Microscope (AFM) – Universal SPM from Ambios Technology

The USPM AFM unit mainly consists of a microscope unit which is composed of the probe and scanner, an electronic interface unit (EIU) and a computer.


  • X-Y Range : 40 microns with a pixel resolution of  6.1 angstom
  • Z Range : 4 microns with a pixel resolution of  0.5 angstrom
  • Scan Rate : 0.25 Hz to 20 Hz
  • Image Resolution: 100×100 to 1024×1024

Operation Mode:

  • Contact mode
  • Intermittent Contact mode
  • Lateral force mode
  • Phase mode

Related Research:

  • Distribution of the Surface Mechanical Properties in Nanocomposites by Spontaneous Embedment of Submicron Particles
  • Mechanics of DPPC Multibilayers: surface properties by
    particle embedment technique
  • Mechanical properties of PETN crystal

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Last updated: 06/09/09.