Thread by @goldclusters

Synchrotron Science & Techniques

My first exposure to synchrotron science started with small & wide-angle X-ray scattering, SAXS & WAXS at Melbourne. I frequented @ausynchrotron. When I started PhD in NZ, I still visited Australian Synchrotron to do XPS

pubs.rsc.org/en/content/art…

2/ We focused on XPS because it can give qualitative insights into the relative size of Au clusters. Imaging these ultrasmall cluster using conventional HRTEM proved to be unsuccessful because the size is <1.5 nm. So, XPS is a good alternative because the BE shift ~ relative size

3/ A big challenge in cluster supported catalysts is to control aggregation & retain the molecular properties. To probe the size evolution, we used a combined XPS & UV-visible DRS. The finding is about the size regime, either cluster <2nm or NP >2nm

pubs.acs.org/doi/abs/10.102…

4/ Why synchrotron XPS? Why not just lab XPS? I give 2 reasons.
1. High flux synchrotron beam allows detection of small Au content (<0.5%). Lab XPS detects this as noise.
2. The cross-section of elements depends on photon energy. Photon energy is tunable at synchrotron.

5/ Plus, there are some tools that are not available in the lab such as X-ray absorption spectroscopy (XAS). (now table top XAS is on the market). XAS has 2 regimes, near edge (XANES) & extended edge (EXAFS). XANES gives info about oxidation state & EXAFS about #coordination.

6/ Different synchrotron facilities have different capabilities. We struggled to record XAS spectra at ANBF in Japan but got high quality data at Australian Synchrotron (AS). Some Europeans that I met at AS told me that the beamlines at AS are more stable than some Europeans'

7/ @ausynchrotron (AS) is unique because it has a THz beamline. It allows us to probe metal core vibrations. DFT predicts that such vibrational modes only appear at low frequency with low intensity. So, synchrotron far-IR is an ideal tool for this.

pubs.rsc.org/en/content/art…

8/ DFT computed vibrational modes in gas phase while far IR spectra recorded in solid state. There is a shift toward longer bond lengths. Nonetheless we found beautiful matches/agreements.

pubs.acs.org/doi/abs/10.102…

9/ The beauty of synchrotron experiments is that you can discuss with the beamline scientists to tailor the experiment to your need. We installed UV lamp at synchrotron XPS to study rate of formation of Ti3+ defects in TiO2 under light irradiation.

pubs.acs.org/doi/10.1021/jp…

10/ There is much more you can do at synchrotron facilities. But I am gonna stop here. The best way to get access is to talk/discuss with the beamline scientists about your experiment. They will advise you accordingly. You may also get the travel & access grant from synchrotron.

@threadreaderapp, please roll.