Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

Заседание семинара состоится в режиме видеоконференции по ссылке.

Local probing of nanoscopic matter by spectroscopy and spectromicroscopy is reviewed. Targets are free nanoparticles in the gas phase, nanoscopic matter in liquid microdroplets, deposited nanosystems, and nanoscopic matter in biological surroundings. The experimental studies are primarily performed by tunable soft X-rays, in the infrared regime, as well as complimentary radiation sources, including free electron lasers and laboratory-based short pulse lasers. The interpretation of the experimental results is supported by model calculations.
Properties of free nanoparticles prepared in a narrow beam are investigated by soft X-rays. This approach has the advantage that single particles without any contact to a substrate are probed so that radiation damage and charging effects induced by photon impact are efficiently suppressed. Light scattering, photoemission, and ion emission studies reveal distinct information on the surface and bulk properties of the nanoparticles [1, 2]. The dynamics of photoemission from free nanoparticles leading to processes occurring in the femto- and atto-second regimes will be briefly discussed. This requires the use of free electron lasers and ultra-short laser pulses [3-5].
Nanoscopic matter can also be formed in levitated supersaturated and supercooled microdroplets for investigating nucleation processes in metastable liquids. Structural properties of pre-nucleation clusters are identified by a combination of near-edge spectroscopy and molecular dynamics calculations [6]. The role of excess charges on the nucleation of liquid microdroplets has been evaluated, since this influences massively the nucleation processes [7].
Finally, topical drug delivery into skin, partially involving nanoparticles, probed by label-free spectromicroscopy is reported. The role of drug formulations and responsive polymeric nanocarriers as efficient drug transport vehicles is evaluated regarding their penetration into deeper skin layers [8]. This also includes thermal and redox triggers [9, 10]. Selective and high spatial resolution detection of drugs and drug nanocarriers is accomplished by X-ray microscopy and complementary methods, such as atomic force microscopy-based spectroscopic approaches in the infrared regime, partially realized by employing compressed sensing approaches [11, 12], and stimulated Raman microscopy [13]. Recent results on the penetration of anti-inflammatory drugs are reported, where the drugs are topically applied to human and murine skin samples ex vivo, reaching a spatial resolution below 10 nm, so that from spectromicroscopy a molecular understanding of processes occurring in biological matter can be reached.

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