More research results:


The intermolecular band dispersion related to the highest occupied molecular orbital in highly-ordered, hydrated multilayer films of the DNA base guanine has been measured using photon-energy-dependent ultraviolet photoelectron spectroscopy. A band width of 331±8 meV at room temperature and a small effective mass of about 1.11 times that of a free charge suggest a high intrinsic hole mobility along quasi-one-dimensional stacks formed perpendicular to layered, hydrogen-bound networks.

Stacks of nucleic acids as molecular wires: Direct measurements of the intermolecular band dispersion in multilayer guanine assemblies,
R. Friedlein, Y. Wang, A. Fleurence, F. Bussolotti, Y. Ogata, Y. Yamada-Takmura, J. Am. Chem. Soc. (Commun.) 132, 12808 (2010).


Electronic and structural properties of thin, chemisorbed adenine films on Cu(110) have been investigated by ARUPS and RHEED. Molecular re-orientation at the particular coverage of about 0.3 monolayers from a disordered flat-lying to a long-range ordered standing-up phase is accompanied by pronounced changes of the interfacial dipole provided by the intrinsic dipole moment of the polar molecule. Interfacial states relate to atom site-specific N-Cu interactions.

Hybrid interfaces of biological molecules and metals: The prototypical case of adenine on Cu(110),
F. Bussolotti, R. Friedlein J. Chem. Phys. 132, 184705 (2010).


Various anthracene thin film phases are characterized by ionization energies varying up to 0.9 eV; the surface dipole and possibly to a minor extend polarization energy contributions are shown to be related to the specific molecular packing/molecular orientation and to the interplay between the molecule-molecule vs. molecule-substrate interactions.

Phase-dependent electronic properties of mono- and multilayer anthracene films on graphite (0001) surfaces,
F. Bussolotti, S.-W. Han, Y. Honda, R. Friedlein, Phys. Rev. B 79, 245410 (2009).


High-yield,two-photon photoionization processes at the optical absorption threshold in thin perylene films are proven to be caused by the annihilation of adiabatically relaxed singlet excitons rather than by direct processes. As a consequence, hole states below the vertical ionization threshold are detected.

Two-photon photoionization by singlet-singlet annihilation in polycrystalline, thin perylene films,
R. Friedlein, Appl. Phys. A 95, 315 (2009).


Upon exposure to water vapor, hydrogen bonds between adenine molecules are replaced by water-adenine hydrogen bonds in a stepwise pattern. The results shed light onto the stability and chemical states of DNA base pairs in aquous environments.

Selective hydrogen bond disruption in adenine monolayer films by reaction with water,
W. J. Doherty III, S. L. Sorensen, R. Friedlein,
J. Electr. Spectr. Relat. Phenom. 174, 107 (2009).


Ordered Films of ionic phthalocyanines can be prepared by repeated dipping. Find out about chances and limitations of this technique!

Layer-by-Layer Deposition of Copper Phthalocyanine from Aquous Solution: Molecular Orientation, Ordering Parameters, and Electronic Structure,
W. J. Doherty III, R. Friedlein, W. R. Salaneck,
J. Phys. Chem. C 2007, 111, 2724.