Spectroscopy and Imaging of Magnetic Nanoparticles
|Datum:||17.02.2020, 17:15 - 19:00 Uhr|
|Ort:||Hubland Süd, Geb. P1 (Physik), Hörsaal P|
|Veranstalter:||Fakultät für Physik und Astronomie|
|Vortragende*r:||PD Dr. Volker Behr|
Am 17.02.2020 hält PD Dr. Volker Behr um 17:15 Uhr im Hörsaal P, Physikalisches Institut, einen Vorstellungsvortrag im Rahmen des Verfahrens zur Verleihung des Titels "außerplanmäßiger Professor" mit dem Thema "Spectroscopy and Imaging of Magnetic Nanoparticles".
The magnetic nanoparticles under consideration in this talk are composed of ferromagnetic material, but their dimensions are so small that only one single magnetic domain exists. While there is still the internal alignment of spins within this domain, the domain as a whole acts as one large magnetic moment, which can be influenced by e.g. externally applied magnetic fields. This state is called superparamagnetism. The specific reaction of particles to magnetic fields is determined by two mechanisms: Néel and Brownian relaxation. The former describes a re-orientation of the magnetic moment within the particle and is governed by the particle’s magnetic anisotropy. The latter refers for re-orientation by rotation of the entire particle, which is strongly dependent on (hydrodynamic) size and environment.
Superparamagnetic iron-oxide nanoparticles are established in magnetic resonance tomography in biomedical applications as contrast agents. However, direct detection promises higher specificity as well as sensitivity. Magnetic particle imaging being such a direct technique has firstly been published in 2005 using time-varying magnetic fields and observing the particles’ response. The basics of this technique along with recent developments and current research projects covering all from scientific apparatus to modelling will be presented in this talk.
Furthermore, I will be highlighting an alternative technique using rotating magnetic fields for spectroscopy and possibly imaging applications on the aforementioned particles. It exploits the transition from locked motion with an externally applied field to a rotationally drifting motion at frequencies specific to the particles as well as the environment. This concept from our labs promises highest sensitivity for probing the particles’ interaction with their environment and can find application in e.g. (bio-)assays.
Weitere Vorträge im Rahmen des Physikalischen Kolloquiums im Wintersemester 2019/20.