The observation of chemical reactions on the time scale of the motion of electrons and nuclei has been made possible by lasers with ever shortened pulse lengths. Superfluid helium represents a special solvent that permits the synthesis of novel classes of molecules that have eluded dynamical studies so far. However, photoexcitation inside this quantum solvent triggers a pronounced response of the solvation shell, which is not well understood. Here, we present a mechanistic description of the solvent response to photoexcitation of indium (In) dopant atoms inside helium nanodroplets (HeN), obtained from femtosecond pump–probe spectroscopy and time-dependent density functional theory simulations. For the In–HeN system, part of the excited state electronic energy leads to expansion of the solvation shell within 600 fs, initiating a collective shell oscillation with a period of about 30 ps. These coupled electronic and nuclear dynamics will be superimposed on intrinsic photoinduced processes of molecular systems inside helium droplets.

The response of a molecule to photoexcitation is governed by the coupling of its electronic states. However, if the energetic spacing between the electronically excited states at the Franck–Condon window becomes sufficiently small, it is infeasible to selectively excite and monitor individual states with conventional time-resolved spectroscopy, preventing insight into the energy transfer and relaxation dynamics of the molecule. Here, we demonstrate how the combination of time-resolved spectroscopy and extensive surface hopping dynamics simulations with a global fit approach on individually excited ensembles overcomes this limitation and resolves the dynamics in the n3p Rydberg states in acetone. Photoelectron transients of the three closely spaced states n3p x , n3p y , and n3p z are used to validate the theoretical results, which in turn allow retrieving a comprehensive kinetic model describing the mutual interactions of these states for the first time.

The response time of state‐of‐the‐art humidity sensors is ≈8 s. A faster tracking of humidity change is especially required for health care devices. This research is focused on the direct nanostructuring of a humidity‐sensitive polymer thin film and it is combined with an optical read‐out method. The goal is to improve the response time by changing the surface‐to‐volume ratio of the thin film and to test a different measurement method compared to state‐of‐the‐art sensors. Large and homogeneous nanostructured areas are fabricated by nanoimprint lithography on poly(2‐hydroxyethyl methacrylate) thin films. Those thin films are made by initiated chemical vapor deposition (iCVD). To the author's knowledge, this is the first time nanoimprint lithography is applied on iCVD polymer thin films. With the imprinting process, a diffraction grating is developed in the visible wavelength regime. The optical and physicochemical behavior of the nanostructures is modeled with multi‐physic simulations. After successful modeling and fabrication a first proof of concept shows that humidity dependency by using an optical detection of the first diffraction order peak is observable. The response time of the structured thin film results to be at least three times faster compared to commercial sensors.

We present an optical FEM simulation model for a nanostructured hydro- gel thin film system. These materials may be use as fast optical sensors in environmental monitoring. The imprinted hydrogel structure acts as a diffraction grating.

Nanotemplates were directly fabricated with a two-photon-polymerisation 3D printer. Afterwards, the templates were coated with a humidity responsive hydrogel using initiated chemical vapor deposition. Finally, the humidity response of the nanostructures was successfully measured.