Expert: Reza Foudazi - 6/24/2008

Question
Hi Reza,

I have a question to ask regarding the Langmuir-BLodgett Trough. I am currently working with stearic acid layer and depositing layers by layers on hydrophilic substrates for eg. quartz,glass  slides and silicon slides, using a Langmuir-Blodgett Trough. Apparently, I managed to deposit the first monolayer on it but subsequent immersion seems to peel off the first layer when going downwards (and possibly reforming back the layer when moving upwards). I know stearic acid undergoes Y-type deposition, but when moving the slide downwards, the meniscus is pointing upwards instead when it should be pointing downwards. The transfer ratio confirm our suspicions that the layer is peeled when moving down.

Please kindly advise, thanks a lot!

Answer
Dear Stanely,
I think this is the method that lots of papers published on it. So, I think you just have some practical errors with your experiments which can be summarized as follows:
1- check the cleanness of your substrate, because it is very important to work in a clean room, extremely cleaned substrates and instruments, etc.
2- slow down the moving speed of your substrate
I hope to have a successful research,
Regards,
Reza