Pyruvic acid proton and hydrogen transfer reactions in clusters.

We investigate ion chemistry in pyruvic acid (PA) clusters in a molecular beam experiment. We generate two types of species, isolated (PA)N clusters and clusters deposited on large water clusters (ice nanoparticles) (PA)N·(H2O)M, M[combining macron] ≈ 390, and follow their chemistry after either 70 eV electron ionization (EI) or 193 nm UV photoionization (PI). In the (PA)N clusters, where the ionization starts with a PA molecule, both the EI and PI yield essentially the same ions: nominally (PA)nHk+, k = 1,2,3,….

Long time scale dynamics of vibrationally excited (HBr) clusters.

We investigated the photodissociation dynamics of vibrationally excited HBr molecules and clusters. The species were generated in a molecular beam and excited with an IR laser to a = 1 vibrational state. A subsequent ultraviolet (UV)-pulse with 243 nm radiation photolysed the molecules to yield H-fragments, which were resonantly ionized by the same UV-pulse (2 + 1 REMPI) and detected in a velocity map imaging (VMI) experiment.

Imaging of rotational wave-function in photodissociation of rovibrationally excited HCl molecules.

We demonstrate a visualization of quantum mechanical phenomena with the velocity map imaging (VMI) technique, combining vibrationally mediated photodissociation (VMP) of a simple diatomic HCl with the VMI of its H-photofragments. Free HCl molecules were excited by a pump infrared (IR) laser pulse to particular rotational J levels of the v = 2 vibrational state, and subsequently a probe ultraviolet laser photodissociated the molecule at a fixed wavelength of 243.07 nm where also the H-fragments were ionized.

Photochemistry of Nitrophenol Molecules and Clusters: Intra- vs Intermolecular Hydrogen Bond Dynamics.

We investigate both experimentally and theoretically the structure and photodynamics of nitrophenol molecules and clusters, addressing the question how the molecular photodynamics can be controlled by specific inter- and intramolecular interactions. Using quantum chemical calculations, we demonstrate the structural and energetic differences between clusters of 2-nitrophenol and 4-nitrophenol, using phenol as a reference system. The calculated structures are supported by mass spectrometry.