The ability to deposit non-volatile molecules onto surfaces in vacuum opens up a wealth of model functional surfaces to be studied using high-resolution techniques such as synchrotron-based electron spectroscopy and STM. While many relatively simple molecules can sublimed in vacuum, the vast majority of molecules and nanostructures are either too large, or too fragile for this route. Here we report on a novel and effective technique for depositing molecules in vacuum based on electrospray ionisation directly from solution. We demonstrate the technique through the deposition of a controlled monolayer coverage of fragile dye molecules onto a TiO2(110) surface for synchrotron investigations of the charge transfer dynamics in molecular solar cells1. We will present our latest synchrotron data using the ‘core-hole clock’ implementation of resonant photoemission, a technique shown to probe charge injection from an adsorbed molecule into the substrate on the low-femtosecond timescale2. We also demonstrate that electrospray deposition in vacuum can also be applied to non-volatile nanostructures such as carbon nanotubes3.
1 M. Grätzel, Nature 414 (2001) 338
2 J. Schnadt, P. A. Brühwiler, L. Patthey, J. N. O'Shea, S. Södergren, M. Odelius, R. Ahuja, O. Karis, M. Bässler, P. Persson, H. Siegbahn, S. Lunell & N. Mårtensson, Nature 418, 620 (2002)
3 J. N. O'Shea et al 2007 Nanotechnology 18 035707 |