Science things from this morning....

Morning all

Amidst some admin work this morning, a couple of research issues are worth mentioning. First, we want to do some work aimed at making PbS nanoparticles. For this we will use a water subphase containing lead acetate or lead nitrate. The lead ions should then be taken up by a floating monolayer of a calixarene that my student Faridah is working on. Faridah will then make multilayer films of up to 80 layers thick and then we'll expose to H2S gas (not nice!) in the same way as we make CdS nanoparticles. The diffusion of H2S through the multilayer should result in:

Pb2+ + H2S ---> PbS + 2 H+ . Accordingly to my mate Alexei (Hallam Univ) PbS nanoparticles should yield transitions in the visible. I guess this makes sense since PbS is a narrow bandgap semiconductor (infra-red) and the quantum confinement would lead to widening of this gap. From a colour point of view, I imagine that the pre-exposure film will be fairly colourless but, provided we can get a sufficiently high density of nanoparticles, after exposure to the H2S, we might see a pink/red colour maybe? Time will tell.....

Secondly, this morning, Mark (another PhD student of mine) started some I-V measurements of gold nanoparticle LS films using the new interdigitated electrodes he's designed and made. We now have a range of gap sizes between the fingers so we can look at field effects as well as basic I-V properties. The other main progress we can make with these electrodes is that I-V's will be measurable with alkanethiol-capped gold cores which are inherently less conducting than our usual methylbenzenethiol-capped nanoparticles. Our 25 micron gap size previously meant that currents from the alkanethiols were too small to measure. So watch this space for a ton of results from Mark over the next few months.

Well, that's it for this morning - it's sandwich time now and Jez at "John's Van" is dependent on me for his summer holiday! A plus, Tim