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UID:69f27c353a769
DTSTART:20210415T130000Z
SEQUENCE:0
TRANSP:OPAQUE
LOCATION:ICFO Auditorium and Online (Teams)
SUMMARY:ICFO | LISA SAEMISCH
CLASS:PUBLIC
DESCRIPTION:The interaction of light and matter is of crucial importance in
  fundamental science as well as in high-end technology.\nUltimately\, this
  concerns the interaction between a photon and a single quantum system\, e
 .g. the absorption or emission of a photon by a single molecule. At room t
 emperature this interaction is very inefficient as the absorption cross-se
 ction of a molecule is small compared to the wavelength of light\, which i
 nhibits many photons from interacting and hence limits the absorption\, em
 ission and scattering of a photon. An equivalent problem\, and its solutio
 n\, is found in our daily lives: small electric circuits (as found e.g. in
  our smartphones)\, which radiate very poorly by themselves\, are linked t
 o (radio) antennas to radiate and transfer information efficiently. Analog
 ously\, antennas working in the visible\, so-called nanoantennas\, are an 
 effective tool to link matter and light. The strength of the coupling of a
  single molecule with a nanoantenna depends on many factors: the overlap o
 f the antenna resonance and the molecular absorption/emission spectrum\, t
 he molecule&rsquo\;s dipole orientation\, the distance between molecule an
 d nanoantenna\, etc. Hence\, strong interaction needs rather special condi
 tions\, which are hard to engineer. Moreover\, to get a full interaction p
 icture\, a lot of single molecule encounters with different nanoantennas a
 re needed - on one hand to make a statistically relevant statement includi
 ng the many different factors and\, on the other hand\, to be able to obse
 rve the rare stronger interactions\, that would have stayed hidden in expe
 riments of only a few encounters. The central idea of this thesis is to st
 atistically map and control the interactions of a very large number of sin
 gle molecules\nwith different tailored nanoantennas\, to cover the landsca
 pe of interaction factors and thus extend the current knowledge of the mut
 ual interaction. For this purpose\, a home-built wide-field microscope is 
 combined with a large array of lithographically fabricated nanoantennas\, 
 which are all probed by freely diffusing molecules. Thus in time millions 
 of encounters are recorded in parallel.\nChapter 2 introduces the necessar
 y knowledge and methodology to understand the research work presented in c
 hapters 3 to 5. Chapter 3 shows super-resolved nanoscale interaction maps 
 of molecules and nanoantennas\, linking the strength of interaction to the
  emission polarization and intensity of every encounter. Chapter 4 extends
  this approach by simultaneously recording the emission fluorescence and s
 pectrum of every single molecule event\, revealing strong spectral manipul
 ation.\nHere\, a suppression as well as an extreme enhancement of the vibr
 ational sideband of the used molecule is observed.\nAdditionally\, the sta
 tistical mapping allows the freely diffusing molecules to encounter rare h
 otspots of extreme field intensities\, enabling the observation of surface
 -enhanced Raman scattering.\nFinally\, chapter 5 takes the first step in t
 he direction of characterizing the interaction of molecule and nanoantenna
  with high sensitivity via phase measurements. Here\, an interferometric w
 ide-field microscope enables the measurement of the absolute phase of nano
 particles and demonstrates the distinction of different plasmonic and diel
 ectric particles via their phase behavior. Furthermore\, we implement a no
 vel two-color excitation method\, capable of rapidly identifying two types
  of nanoparticles in a single-shot image.
DTSTAMP:20260429T214629Z
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