The Helium Drop Laboratory
AIn the fields of physical chemistry and molecular physics, superfluid helium nanodrops have become established as a carrier system for the production of cold samples such as individual atoms, molecules, or homogeneous and heterogeneous clusters. At a temperature of just 0.38 (1) K, the isotope 4He enters the superfluid phase and behaves like a quantum fluid. The key properties are high thermal conductivity and negligible viscosity. Compared with alternative host systems, the disruptive influence of superfluid helium on a gas system is negligible. However, even with sufficient energy resolution, a negligible disturbance is far from the absence of any disturbance whatsoever.
Building on our experience in the fields of photophysics and photochemistry, our laboratory is dedicated to investigating guest-host interactions observed in molecules or molecular clusters within nanodroplets of superfluid helium. Our experimental approach involves electronic spectroscopy using a single-mode auto-scan ring-dye laser with a bandwidth of less than 1 MHz. Following electronic excitation, the fluorescence response is recorded as a function of the excitation frequency (fluorescence excitation spectrum) or dispersed using a grating spectrograph, with the excitation frequency remaining fixed at a molecular resonance.
Our experimental work is currently focused on identifying the rotational band structure within the line shapes of electronic transitions in molecules within helium nanodrops.