The ANKA-IR2 Nanoscope and Micro- and Nanospectroscopy Applications

We report on a newly developed and integrated microscopy and nanoscopy station at the ANKA-IR2 beamline. We further elucidate how vibrational near-field and microspectroscopy can give new insights in medical applications

Special Libraries, April 1933

Volume 24, Issue 3https://scholarworks.sjsu.edu/sla_sl_1933/1002/thumbnail.jp

EuPRAXIA - A compact, cost-efficient particle and radiation source

Plasma accelerators present one of the most suitable candidates for the development of more compact particle acceleration technologies, yet they still lag behind radiofrequency (RF)-based devices when it comes to beam quality, control, stability and power efficiency. The Horizon 2020-funded project EuPRAXIA ("European Plasma Research Accelerator with eXcellence In Applications") aims to overcome the first three of these hurdles by developing a conceptual design for a first international user facility based on plasma acceleration. In this paper we report on the main features, simulation studies and potential applications of this future research infrastructure

PROBING HYDROGEN BOND NETWORK VIBRATIONS IN CARBOHYDRATE SOLVATION SHELLS AT THZ FREQUENCIES

U. Heugen, G. Schwaab, E. Brundermann, M. Heyden, X. Yu, D.M. Leitner, and M. Havenith PNASM. Heyden, G. Niehues, U. Heugen, D.M. Leitner, and M. Havenith JACSAuthor Institution: Lehrstuhl fur Physikalische Chemie II, Ruhr-Universitat Bochum, 44780 Bochum, Germany; Department of Chemistry, University of Nevada, Reno, NV 89557; Lehrstuhl fur Physikalische Chemie II, Ruhr-Universitat Bochum, 44780 Bochum, GermanyWe have employed THz spectroscopy to study properties of the hydrogen bond network of water directly, whose collective vibrational modes are known to be resonant in this frequency range. A table-top THz spectrometer with a p-Germanium laser source emitting 2W pulses, was used to perform measurements on strongly absorbing aqueous solutions of different carbohydrates. The high output power of the laser source in combination with a difference setup enabled us to determine changes of the solution's absorption coefficient due to increasing carbohydrate concentration with high precision. The acquired data were modeled with an approach assuming a random distribution of the solvated molecules} 2006, vol. 103, no. 133, 12301-12306}. The model allows for the extraction of the absorption coefficent of solvation shell water as well as the actual size of the solvation shell. We find a general increase of the absorption coefficent in the solvation shell that we ascribe to a retardation of water dynamics on picosecond timescales as found by molecular dynamics simulations. The range of this effect or the actual thickness of the solvation shell as probed by our method lies between 3.7~{\AA} for the monosaccharide glucose and 6.5~{\AA} for the disaccharide trehalose}} 2008, \textit{accepted}}. These results indicate that the solvation shell of a carbohydrate molecule not only consists of the first layer of water molecules but also includes the second layer and may even involve a third one as in the case of trehalose. The strength of the effect we observe in THz absorbance strongly correlates with the number of hydrogen bonds formed between the solute molecule and the solvent. We therefore conclude that they provide the link between the solute and its solvation shell, forcing the solvating water to change its dynamical properties

Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy

The dynamics of water surrounding a solute is of fundamental importance in chemistry and biology. The properties of water molecules near the surface of a bio-molecule have been the subject of numerous, sometimes controversial experimental and theoretical studies, with some suggesting the existence of rather rigid water structures around carbohydrates and proteins [Pal, S. K., Peon, J., Bagchi, B. & Zewail A. H. (2002) J. Phys. Chem. B 106, 12376–12395]. Hydrogen bond rearrangement in water occurs on the picosecond time scale, so relevant experiments must access these times. Here, we show that terahertz spectroscopy can directly investigate hydration layers. By a precise measurement of absorption coefficients between 2.3 THz and 2.9 THz we could determine the size and the characteristics of the hydration shell. The hydration layer around a carbohydrate (lactose) is determined to extend to 5.13 ± 0.24 Å from the surface corresponding to ≈123 water molecules beyond the first solvation shell. Accompanying molecular modeling calculations support this result and provide a microscopic visualization. Terahertz spectroscopy is shown to probe the collective modes in the water network. The observed increase of the terahertz absorption of the water in the hydration layer is explained in terms of coherent oscillations of the hydration water and solute. Simulations also reveal a slowing down of the hydrogen bond rearrangement dynamics for water molecules near lactose, which occur on the picosecond time scale. The present study demonstrates that terahertz spectroscopy is a sensitive tool to detect solute-induced changes in the water network