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We perform laser spectroscopy at liquid helium temperatures (T=2 K) to investigate single dibenzoterrylene (DBT) molecules doped in anthracene crystals of nanoscopic height fabricated by electrohydrodynamic dripping. Using high-resolution…
Single-molecule fluorescence spectroscopy is a powerful method that avoids ensemble averaging, but its temporal resolution is limited by the fluorescence lifetime to nanoseconds at most. At the ensemble level, two-dimensional spectroscopy…
Many fundamental processes of structural changes at surfaces occur on a pico- or femtosecond time scale. In order to study such ultra-fast processes, we have combined modern surface science techniques with fs-laser pulses in a pump-probe…
A single-walled carbon nanotube presents a seamless cylindrical graphene surface and is thus an ideal adsorption substrate for investigating the physics of atoms and molecules in two dimensions and approaching the one-dimensional limit.…
Single molecules in solids have been considered as an attractive class of solid-state single quantum systems because they can be chemically synthesized at low cost to have stable narrow transitions at desired wavelengths. Here we report and…
Molecule-surface interaction is key to many physical and chemical processes at interfaces. Here, we show that the dynamics of single molecules on a surface under ultrahigh vacuum can be resolved using fluorescence imaging. By adapting…
The behavior of a polyelectrolyte adsorbed on a charged surface of high-dielectric constant is studied by both Monte-Carlo simulation and analytical methods. It is found that in a low ionic strength medium, the transition is first-order…
The behavior of a polyelectrolyte adsorbed on a charged substrate of high-dielectric constant is studied by both Monte-Carlo simulation and analytical methods. It is found that in a low enough ionic strength medium, the adsorption…
Absorption microscopy is a powerful technique, enabling the detection of single non- fluorescent molecules at room temperature. So far, the molecular absorption has been probed optically via the attenuation of a probing laser. The…
Rare-earth doped nanocrystals possess optical transitions with significant either electric or magnetic dipole characters. They are of strong interest for understanding and engineering light-matter interactions at the nanoscale with numerous…
My thesis mostly focusses on the systems of porphyrin molecules adsorbed on single-crystalline metallic surfaces. Cyclic tetrapyrrole porphyrins play key roles in many important chemical and biological processes, such as oxygen transport in…
Helium is recognized as a model system for the study of phase transitions. Of particular interest is the superfluid phase in two dimensions. We report measurements on superfluid helium films adsorbed on the surface of a suspended carbon…
An ultrafast photoemission-based low-energy electron diffraction experiment with monolayer surface sensitivity is presented. In a first experiment on tin-phthalocyanine adsorbed on graphite, we demonstrate a time resolution of approx. 100…
A suspended carbon nanotube can act as a nanoscale resonator with remarkable electromechanical properties and the ability to detect adsorption on its surface at the level of single atoms. Understanding adsorption on nanotubes and other…
We investigate deuterium atoms adsorbed on the surface of liquid helium in equilibrium with a vapor of atoms of the same species. These atoms are studied by a sensitive optical method based on spectroscopy at a wavelength of 122 nm,…
High-resolution gas phase spectroscopy techniques in the microwave, millimeter-wave and terahertz spectral ranges can be used to study complex organic molecules desorbed from interstellar ice analogues surface with a high sensitivity.…
We present a novel method to measure transient photovoltage at nanointerfaces using ultrafast electron diffraction. In particular, we report our results on the photoinduced electronic excitations and their ensuing relaxations in a…
Single molecule spectroscopy aims at unveiling often hidden but potentially very important contributions of single entities to a system's ensemble response. Albeit contributing tremendously to our ever growing understanding of molecular…
Transient X-ray absorption techniques can measure ultrafast dynamics of the elemental edges in a material or multiple layer junction, giving them immense potential for deconvoluting concurrent processes. However, the interpretation of the…
Phase-locked ultrashort pulses in the rich terahertz (THz) spectral range have provided key insights into phenomena as diverse as quantum confinement, first-order phase transitions, high-temperature superconductivity, and carrier transport…