Interaction of self-assembled monolayers of DNA with electrons: HREELS and XPS studies.

We present results from high-resolution electron energy loss spectroscopy (HREELS) and XPS studies of self-assembled monolayers of DNA. The monolayers are well-organized and display sharp vibrational peaks in the HREEL spectra. The electrons interact mainly with the backbone of the DNA. The XPS results indicate that, in most of the samples studied, the phosphates on the DNA are not charged.

New hybrid films based on cellulose and hydroxygallium phthalocyanine. Synergetic effects in the structure and properties.

Hydroxygallium phthalocyanine (HOGaPc) and cellulose (from a trimethylsilyl derivative) have been used as native elements for the preparation of a novel family of hybrid films. By spin-coating, both components allow the building of films with different configurations on various substrates in a controlled way. The particularities of these hybrid films have been characterized by a range of techniques such as Fourier transform infrared spectroscopy (FTIRS) in attenuated total reflection using multiple internal reflections (ATR/MIR), absorption ultraviolet and visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and surface potential measurements using the Kelvin-Zisman vibrating capacitor probe (KP). This enabled determination of the influence of cellulose on the arrangement of HOGaPc and, consequently, control of the relation between the structure and the properties of the films. Finally, gas sensor tests were performed to check the potentialities of these hybrid films. In particular, the synergetic behavior between the film-forming materials allows a fast and sensible change in surface potential after cyclic exposures to ozone (O3, 100 ppb) and nitrogen. Overall, we present the advantages of combining phthalocyanine with cellulose in enhancing the properties of the final product. Introduction of cellulose as a host material opens up a new area of hybrid films.