Works of art are valuable and often also very delicate. Their restoration and conservation and their dating and authentication require sophisticated technical methods. A team led by Sichun Zhang at Tsinghua University in Beijing has now developed a new imaging mass spectrometric process to identify paintings and calligraphy without damaging the art pieces. As the scientists report in the journal Angewandte Chemie, the secret to the success of this method is a low-temperature plasma probe that gently removes molecules from the surface of the art works.
In mass spectrometry (MS), the substance to be examined is brought into the gas phase and ionized (electrically charged); the ionized particles are then accelerated through by an electric field. Within the analyzer, the particle beam is separated according to the mass and charge of the particles. Imaging mass spectrometric techniques have now also been developed. In this process, the surface of a sample must be scanned and a mass spectrum obtained at every pixel. This technique requires special ionization methods that allow the samples to be examined directly. However, most of the existing imaging mass spectrometric techniques work under vacuum conditions, which limits the size of the samples to be analyzed. In the electrospray technique, solvent molecules carry analyte molecules away from the surface and ionize them.
Delicate works of art such as paintings can however be contaminated and thus damaged by the solvents. The Chinese researchers have now introduced a new variety of imaging MS that operates with a low-temperature plasma probe. This probe essentially consists of a fused capillary and two electrodes made of aluminum foil, to which a very strong alternating voltage is applied. Inside the capillary there is helium gas; the high electric voltage induces what is known as a dielectric barrier discharge in the helium. This means that the helium atoms are in the form of separated ions, electrons, and exited atoms, a state known as a plasma. The temperature of this plasma reaches only 30 °C. The helium plasma leaving the capillary ejects molecules from the surface of the sample and ionizes them. This does not damage valuable works of art.
The scientists used this new technique to analyze seals, which are stamped impressions used as signatures and means of authentication on Chinese paintings and calligraphy. The team was able to use their new microplasma probe to reveal variations in the composition of the ink of individual seals, making it possible to differentiate between authentic and inauthentic seals.
Please note our event "Frontiers of Chemistry" on May 21 in Paris with four Nobel laureates and six other renowned speakers. It will be broadcast live on the internet at chemistryviews.org.
Author: Sichun Zhang, Tsinghua University, Beijing (China), http://chem.tsinghua.edu.cn/zhangxr/xrzhang.htm
Title: Imaging Mass Spectrometry with a Low-Temperature Plasma Probe for the Analysis of Works of Art
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.200906975
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
Biological signalling processes in intelligent materials
18.07.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Life Sciences
18.07.2018 | Information Technology