PCCP Blog

Scientists using computational techniques to look at electron-transfer processes in DNA have employed a surface-hopping approach to predict the degree of charge localisation across nucleobases. The technique should allow more accurate modeling of the effects of charge transfer within the molecule.

Different computational approaches often predict varying degrees of charge delocalisation. The commonly used mean-field method often exaggerates the degree to which charge is spread out, because of the self-interaction error inherent to DFT modeling. The surface-hopping method used in this study, however, does not suffer from such difficulties and treats transitions between charge states as distinct jumps between states.

Check out the full details of this exciting article:

Efficient algorithms for the simulation of non-adiabatic electron transfer in complex molecular systems: application to DNA
Tomáš Kubař and Marcus Elstner
DOI: 10.1039/C3CP44619K

Telecommunication operates primarily in three wavelength windows: 750 nm to 850 nm, 1310 nm and 1530 nm to 1560 nm; where the latter is the best as a consequence of low loss-levels and the invention of erbium signal amplifiers. Nevertheless, other carbon based materials are sought in an attempt to replace, and maybe supersede, the rare earth containing systems that are used today.
Xiaoting Liu and co-workers have in ‘New insights into two-photon absorption properties of functionalized aza-BODIPY dyes at telecommunication wavelengths: a theoretical study’ embarked on a road toward the better understanding of two-photon cross-sections. In this particular case, systems based on BODIPY dyes are under theoretical scrutiny, in attempt to find a system that can work—via two-photon absorption—in the optical windows used in telecommunication.

The fact that the direct absorption of the f–f transitions are low—typically with molar absorptivities below 1 M^-1cm^-1—are the reason why two-photon processes might be able to compete with absorption by lanthanide ions. The systems studied in the paper never quite reach the 1510 nm window, but do make it to 1310 nm by two-photon absorption. In fact, single photon absorption of some of the systems under investigation is found to be in the high energy/high frequency range of the telecommunication window around 800 nm.

Intrigued? For the molecular structures and much, much more see:

New insights into two-photon absorption properties of functionalized aza-BODIPY dyes at telecommunication wavelengths: a theoretical study
Xiaoting Liu, Jilong Zhang, Kai Li, Xiaobo Sun, Zhijian Wu, Aimin Ren and Jikang Feng
Phys. Chem. Chem. Phys., 2013, 15, 4666-4676
DOI: 10.1039/C3CP44435J

by Dr Thomas Just Sørensen

This paper from the group of Matthias Arenz at the Nano-Science Center at the University of Copenhagen may prove crucial for comparing catalysts and catalyst matrices for low temperature fuel cells.

In “Pt based PEMFC catalysts prepared from colloidal particle suspensions – a toolbox for model studies” Speder and co-workers demonstrate the applicability of their approach to catalyst fabrication in a model study. The key result is that their catalyst synthesis allow for accurate comparison of different catalyst systems as their procedures are reproducible and yield consistent results.

Fuel cell catalysts on solid supports have been difficult to compare, as the means of their preparation introduce differences, often larger than those variations resulting from the parameter under study. The work summarized in this paper opens a way around this issue, making comparative study feasible. Of this reason alone you should have a look at the paper. On top of that you get the interesting result regarding the anchoring of Pt catalyst particles to the carbon support.

by Dr Thomas Just Sørensen

Read the full details of this HOT PCCP article today:

Pt based PEMFC catalysts prepared from colloidal particle suspensions – a toolbox for model studies
Jozsef Speder, Lena Altmann, Melanie Roefzaad, Marcus Bäumer, Jacob J. K. Kirkensgaard, Kell Mortensen and Matthias Arenz
DOI: 10.1039/C3CP50195G