Spectroscopy

The study of the interaction between matter and electromagnetic radiation is called Spectroscopy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. Later the concept was expanded greatly to include any interaction with radiative energy as a function of its wavelength or frequency. Spectroscopic data is often represented by a spectrum, a plot of the response of interest as a function of wavelength or frequency.

  • “Bethe Strings” Experimentally Demonstrated as Many-Body Quantum States for the First Time

    In SrCo₂V₂O₈ the cobalt ions (CO²⁺) form in the interior of a chain of edges-linked oxygen octahedra a quasi-one-dimensional electron spin chain with spin S = ½. © Universität Augsburg/IfP/EP V

    The synthesis of quasi one-dimensional magnets and their investigation by means of optical spectroscopy in extremely high magnetic fields led to success. Augsburg /AL/KPP - “Bethe strings” are excitations of strongly bound electron spins in one-dimensional quantum spin systems. These quantum spin states are named after the physicist Hans Bethe, who first described them theoretically in 1931.

  • A New Home for Optical Solitons

    Developement of new enhancement cavities at the Laboratory for Attosecond Physics. Thorsten Naeser

    Laser physicists based at the Laboratory for Attosecond Physics run by the Max Planck Institute of Quantum Optics and the Ludwig-Maximilian University have, for the first time, generated dissipative solitons in passive, free-space resonators. Solitons are the most stable of all waves. Under conditions that result in the dispersion of all other waveforms, a soliton will continue undisturbed on its solitary way, without changing its shape or velocity in the slightest. The self-stabilizing properties of solitons explain their immense significance to the field of laser optics, in particular for the generation of ultrashort light pulses.

  • A signal boost for molecular microscopy

    A signal boost for molecular microscopy | Schematic illustration of the experiment. Graphic: MPQ, Laser Spectroscopy Division

    Cavity-enhanced Raman-scattering reveals information on structure and properties of carbon nanotubes. The inherently weak signals are amplified by using special micro cavities as resonator, giving a general boost to Raman spectroscopy as a whole.

  • Auch das Deuteron gibt Rätsel auf: Proton und Deuteron doch kleiner als gedacht?

    Auch das Deuteron gibt Rätsel auf Proton und Deuteron doch kleiner als gedacht picture1 | Karsten Schuhmann und Aldo Antognini an dem Lasersystem, das für die Laserspektroskopie eingesetzt wurde. Foto: Paul Scherrer Institut/Markus Fischer

    Das Deuteron – ein Atomkern aus nur einem Proton und einem Neutron – ist deutlich kleiner als bislang gedacht. Zu diesem Ergebnis kommt eine internationale Forschungsgruppe, die Experimente am Paul Scherrer Institut PSI durchgeführt hat. Dies passt zu einer Studie aus dem Jahr 2010, bei dem dieselbe Forschungsgruppe das Proton vermessen und damit das "Rätsel um den Protonradius" begründet hatte. Nun gibt die Deuterongrösse ein analoges Rätsel auf. Womöglich wird dies zu einer Anpassung der Rydbergkonstante führen. Die Experimente fanden an der weltweit leistungsstärksten Myonenquelle am PSI statt, wo die Forschenden mittels Laserspektroskopie sogenanntes myonisches Deuterium vermassen.

  • Cryo-force Spectroscopy Reveals the Mechanical Properties of DNA Components

    At low temperatures, a DNA strand is removed from the gold surface using the tip of an atomic force microscope. In the process, physical parameters can be determined. Image: University of Basel, Department of Physics

    Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.

  • Die extrem breite IR-Absorptionsbande des Wassers

    Die extrem breite IR Absorptionsbande des Wassers picture 1 | Abb. 1: Die Hydratisierung von Protonen geht weit über das typische Textbuchbeispiel des Hydroniums (H₃O⁺) hinaus.

    Die Ursache der extrem breiten Infrarotabsorption von Protonen in wässriger Umgebung wird seit langem kontrovers diskutiert. Ein Forscherteam des Max-Born-Instituts in Berlin und der Ben Gurion Universität des Negev in Beer-Sheva zeigt jetzt am Beispiel des Zundel-Kations (H₂O...H⁺...OH₂) H₅O₂⁺, dass die umgebende Flüssigkeit fluktuierende elektrische Kräfte auf das Proton ausübt und damit seine Schwingungsbewegung zwischen den beiden Wassermolekülen moduliert. Dieser Mechanismus ruft zusammen mit niederfrequenten thermischen Bewegungen die extreme Verbreiterung des Infrarotspektrums hervor.

  • Kristalluntersuchung mit dreidimensionalen Beugungsmustern

    Kristalluntersuchung mit dreidimensionalen Beugungsmustern | Dreidimensionale Röntgenbeugungsmethode zur Bestimmung der kristallographischen Textur Abbildung: Wiley-VCH

    Trifft Röntgenstrahlung auf einen Kristall wird sie gebeugt und abgelenkt. Die sich daraus ergebenden Beugungsmuster werden auf einer Detektorfläche registriert und sind zweidimensionale Projektionen der Kristallstruktur. Diese Methode wird schon lange zur Strukturaufklärung genutzt. Forschern ist es nun gelungen dieser Projektion eine dritte Dimension hinzuzufügen: die Röntgenphotonenernergie.

  • Leipziger Physiker lösen 80 Jahre altes Problem der Raman-Spektroskopie

    Physiker der Universität Leipzig haben ein 80 Jahre altes Problem der sogenannten Raman-Spektroskopie gelöst. Die Forscher um Prof. Dr. Marius Grundmann stellten eine Theorie auf und erklärten damit die bei der Raman-Streuung auftretenden Intensitäten für beliebig orientierte Kristalle aller Klassen. Ihre Erkenntnisse haben sie kürzlich im Fachjournal "Physical Review Letters" veröffentlicht.

  • Matter-antimatter symmetry confirmed with precision record

    Sketch of the experimental setup used at CERN for the determination of the antiproton-to-electron mass ratio. Graphic: Masaki Hori

    CERN experiment sets precision record in the measurement of the antiproton to electron mass ratio using a new innovative cooling technique. According to the Standard Model of elementary particle physics, to each particle exists an antiparticle that is supposed to behave exactly the same way. Thus, “anti-people” in an “anti-world” would observe the same laws of physics, or make the same experiences in general, as we do. This postulate is, however, difficult to prove, since it is almost impossible to perform measurements on antimatter: whenever an antiparticle meets is matter-counterpart, both particles annihilate, accompanied by the creation of energy.

  • Molecular Switch Will Facilitate the Development of Pioneering Electro-optical Devices

    Electrically switchable organic molecule. Image: Yuxiang Gong / TUM / Journal of the American Chemical Society

    A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

  • Molecules change shape when wet

    The preferred structure of a crown ether changes when water molecules bind to it (dashed lines). © C. Pérez et al.

    Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water. In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max Planck Institute for the Structure and Dynamics of Matter at CFEL and from the Hamburg Centre for Ultrafast Imaging (CUI) show that water promotes the reshaping of crown ethers and biphenyl molecules, two classes of chemically fascinating molecules. Crown ethers are key systems in catalysis, separation and encapsulation processes, while biphenyl-based systems are employed in asymmetric synthesis and drug design.

  • Multiplexed Morse signals from cells

    How many sorts, in how many copies? The biochemical processes that take place in cells require specific molecules to congregate and interact in specific locations. A novel type of high-resolution microscopy developed at the Max Planck Institute for Biochemistry in Martinsried and Harvard University already allows researchers to visualize these molecular complexes and identify their constituents. Now they can also determine the numbers of each molecular species in these structures. Such quantitative information is valuable for the understanding of cellular mechanisms and how they are altered in disease states. The new technique is described in Nature Methods.

  • Nanodiscs: kleine Scheiben ganz groß

    Schematische Darstellung der Extraktion von Membranproteinen aus einer biologischen Membran (oben) unter Bildung von Nanodiscs (unten).

    Biophysiker, Biologen und Chemiker der Technischen Universität Kaiserslautern haben eine neue Art von Polymer/Lipid-Nanopartikeln entwickelt, mit denen Membranproteine im Reagenzglas und dennoch unter fast natürlichen Bedingungen untersucht werden können. Membranproteine spielen viele essenzielle Rollen beim Stoff- und Informationsaustausch zwischen und innerhalb von Zellen. Fehlfunktionen dieser wichtigen Klasse von Biomolekülen führen oft zu schweren Krankheiten, weshalb Membranproteine sowohl in der Grundlagen- als auch in der Wirkstoffforschung intensiv erforscht werden. Eine große Hürde für in-vitro-Untersuchungen - also Studien im Reagenzglas unter genau kontrollierten Bedingungen - sind dabei die hohen Anforderungen, die Membranproteine an ihre Umgebung stellen. Da diese Moleküle sich in Wasser und ähnlichen polaren Flüssigkeiten nicht lösen lassen, sind Forscherinnen und Forscher auf sogenannte „membranmimetische“ Systeme angewiesen, die die natürliche Lipidumgebung mit einer wasserabweisenden Schicht zwischen zwei wasserzugänglichen Grenzflächen möglichst gut nachbilden.

  • New 2D Spectroscopy Methods

    Laser pulse sequences (u.l.) cause 2D spectra (u.r.): In EEI2D spectroscopy (b.l.), two originally separate excitations meet. With 2D mass spectrometry (r.), ion photoproducts are detected. Graphic: Tobias Brixner, JMU

    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.

  • New record achieved in terahertz pulse generation

    Illustration of a broadband terahertz amplifier based on a quantum cascade laser.  TU Wien

    A group of scientists from TU Wien and ETH Zurich have succeeded in their attempts to generate ultrashort terahertz light pulses. With lengths of just a few picoseconds, these pulses are ideally suited to spectroscopic applications and enable extremely precise frequency measurements to be taken. 

  • Novel Spectroscopy Technique Reveals Water Molecule Dance

    3-D model of liquid water (oxygen red, hydrogen white): Intra- and intermolecular vibrations of hydrogen bonds (green) let the whole network "dance". © Max Planck Institute for Polymer Research

    Scientists at the Max Planck Institute (MPI) for Polymer Research have developed the novel 2D TIRV spectroscopy technique to observe coupling between intramolecular and intermolecular vibrations that make water molecules “dance”. Liquid water is permeated by a highly dynamic network of strong hydrogen bonds. Motions of molecules in this network underlie fundamental physical and chemical phenomena.

  • Observing and Controlling Ultrafast Processes with Attosecond Resolution

    Measuring chamber at TUM’s Department of Physics. Photo: Michael Mittermair / TUM

    Many chemical processes run so fast that they are only roughly understood. To clarify these processes, a team from the Technical University of Munich (TUM) has now developed a methodology with a resolution of quintillionths of a second. The new technology stands to help better understand processes like photosynthesis and develop faster computer chips.

  • Positrons as a new tool for lithium ion battery research: Holes in the electrode

    Thomas Gigl and Stefan Seidlmayer at the positron source NEPOMUC. Photo: Wenzel Schürmann / TUM

    Rechargeable lithium batteries with cathodes comprising nickel, manganese, and cobalt, are viewed as the most potent today. But they, too, have a limited lifespan. Already in the first cycle they lose up to ten percent of their capacity. Why this happens and what can be done to alleviate the ensuing gradual loss of capacity has now been investigated in detail by a team of scientists using positrons at the Technical University of Munich (TUM).

  • Shrinking the Proton Again!

    This photo shows the vacuum chamber used to measure the 2S-4P transition frequency in atomic hydrogen. The purple glow in the back stems from the microwave discharge that dissociates hydrogen molecules into hydrogen atoms. The blue light in the front is fluorescence from the ultraviolet laser that excites the atoms to the 2S state. The turquoise blue glow is stray light from the laser system used to measure the frequency of the 2S-4P transition. (Photo: MPQ)

    Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen. It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly smaller, by four standard deviations, than previous determinations using regular hydrogen. This discrepancy and its origin have attracted much attention in the scientific community, with even extensions of the so-called standard model of physics being discussed.

  • Terahertzstrahlung: neuentwickelte Quelle deckt gesamtes Terahertzspektrum ab

    Terahertzstrahlung neuentwickelte Quelle deckt gesamtes Terahertzspektrum ab picture2 |Ein Laserimpuls treibt Elektronen aus einer magnetischen in eine nichtmagnetische Metallschicht. Der dabei entstehende Strom entlang des roten Pfeils erzeugt den Terahertz-Impuls. FHI/Nature Photonics 2016

    Für die Kontrolle von Lebensmitteln und Medikamenten könnte es künftig ein leistungsfähiges und preiswertes Instrument geben. Wissenschaftler des Berliner Fritz-Haber-Institutes der Max-Planck-Gesellschaft haben mit nationalen und internationalen Partnern eine neuartige Quelle für Terahertzstrahlung entwickelt die erstmals das gesamte Terahertzspektrum abdeckt. Somit wird es deutlich einfacher, diese Strahlung zu erzeugen, die sich gut zur Analyse weicher Materialien eignet und daher künftig vermehrt in der Lebensmittel- und Pharmaindustrie Anwendung finden könnte.