Thursday, February 23, 2012

Monolayer formation update

Work has continued in attempting to create monolayers.  SEM was performed and showed that monolayers have indeed been produced, but they are slightly patchy.  The Langmuir-Blodgett trough is still being used but have slightly altered the method for withdrawal and hoping this will form full monolayers.  Another option to be tried in this coming week is to make new solutions of spheres using a 1:1 mixture of H20 and MeOH to try and affect the patchiness of the layers.

Wednesday, February 15, 2012

Working with silica update

Silicon wafers were placed in an oven at 900 degrees C for 3 hours in order to apply a thermal oxide layer for SiO2.  They were then cut using a diamond tipped etching tool and have been running tests using the modified Langmuir-trough setup to observe the film on the surface.  So far have used 100 and 200 nm sphere solutions with films that are almost fully complete after examination with the naked eye.  However, there are still a few spots which should not be bare and therefore we will be working on changing the speed of the trough "floaters", which maintain the surfactant concentration near the surface of the substrate as it's being withdrawn.  My hope is that by increasing the speed and making sure that the substrate does not come into contact with the floaters, the increased surfactant concentration near the substrate surface will allow for a more even coating of the spheres.  If this does not increase the uniformity of the film then another option would be to increase the SDS concentration in an attempt to increase the concentration of individual spheres (non-aggregated) near the liquid-air interface.