Spread the Monolayer


  • Gloves are required and be sure the hood in the lab room is on.
  • Fill the trough in the spectrometer with water obtained from the Milli-Q machine.
  • Pour the water onto the glass area at a steady rate (to avoid splashing), until the water level is above the glass.
  • Remove any excess water.  The optimum water level is one that is just above the glass surface, so any motion waves on the surface of the water are dampened when they reach the area over the glass.
  • Move the trough barrier to -240 mm.
  • When the barrier is finished moving, set the digital multimeter to channel 7 and to milivolts.  Channel 7 is a measurement of the surface pressure of the trough.
  • To normalize the surface pressure, the offset must be turned until the multimeter reads ~0 mV.
  • These next three steps are done under the hood and all waste is put into labeled containers.
  • Clean a syringe of practical size with a methanol/chloroform solution (1 to 3 ratio) six times.
  • Rinse the syringe with the sample, empty.
  • Draw in the amount of sample you want to spread.
  • Double check the digital multimeter to be sure it still reads ~0 mV.
  • To spread the sample, let a drop form on the needle of the syringe and then touch the surface of the water with the drop.
  • Do this in a different place for each drop, on the glass side of the barrier, but not onto the glass, only around it.
  • Cover the trough area with it's lid (leave it craked open though) and let it sit 10 minutes.
  • While waiting, you can clean the syringe with the methanol/chloroform solution.
  • After the time is up, close the chamber tight and fill it with a medium (He) if necessary.
  • You are ready to start your isotherm.