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Nguyen Xuan Truong

Nguyen Xuan Truong

The University of Manchester, United Kingdom

Title: Spectroscopy of small doped silicon clusters

Biography

Dr. Nguyen Xuan Truong earned his PhD in 2011 with Prof. Meiwes-Broer at the University of Rostock in Germany. He then joined the XUV science group of Prof. Vrakking at the Max-Born Institute in Berlin. In 2013, he moved to the TU Berlin as a project leader studying silicon containing clusters. In 2016, Dr. Truong was appointed as a research fellow of the Dalton Nuclear Institute in Manchester. His current research interests include coherent diffractive imaging, laser-enhanced ionization spectroscopy, and time and angular resolved photoemission spectroscopy of metal surfaces and interfaces.

Abstract

Doping Si clusters changes their physical and chemical properties in a way that might be promising for the miniaturization trend towards nanoelectronics and nanophotonics. Here, we investigated Si clusters doped with C, B and N with resonant infrared-ultraviolet two-color ionization (IR-UV2CI) and global optimization coupled with electronic structure methods. Doped Si clusters are irradiated with tunable IR light from a Free Electron Laser before being ionized with UV photons from an F2 laser. Resonant absorption of IR photons leads to an enhanced ionization efficiency for the neutral clusters and provides the size-specific IR-UV2CI spectra. Structural assignment of the clusters is achieved by comparing the experimental IR-UV2CI spectrum with the calculated linear absorption spectra of the most stable isomers. Low-energy isomers are found with genetic and basin-hopping algorithms. For Si𝑚C𝑛 (with 𝑚 + 𝑛 = 6), we observed the systematic transition from chain like geometries for C6 to 3D structures for Si6. We showed for the first row doped Si6X (with X = Be, B, C, N, O) clusters that different structures, vibrational and electronic properties can be achieved depending on the nature of the dopant atom. All dopant atoms in Si6X have a negative net charge suggesting that Si atoms act as electron donors within the clusters. Finally, novel methods to characterize materials based on the high-order harmonic generation XUV sources will be briefly introduced.