Jaanus Kruusma

Manganese detection in marine sediments: anodic vs. cathodic stripping voltammetry

Three different electroanalytical techniques for the detection of manganese in marine sediments are evaluated. The anodic stripping voltammetry of manganese at an in situ bismuth-film-modified boron-doped diamond electrode and cathodic stripping voltammetry at a carbon paste electrode are shown to lack the required sensitivity and reproducibility whereas cathodic stripping voltammetry at a bare boron-doped diamond electrode is shown to be reliable and selective with a limit of detection, from applying a 60s accumulation period of 7.4 x 10(-7)M and a sensitivity of 0.24AM(-1). The method was used to evaluate the manganese content of marine sediments taken from Sibenik, Croatia.

Valence electronic structure of [EMIM][BF4] ionic liquid: photoemission and DFT+D study

The ultraviolet photoelectron spectrum (UPS) of the [EMIM][BF4] ionic liquid was recorded and analyzed. Together with the gas-phase UPS spectrum of the [EMIM][BF4] vapor and ab initio calculation methods, detailed insight into the electronic structure of this simple ionic liquid is possible. The low binding energy tail in the UPS spectrum is about 7.4 eV, in agreement with previous estimations of the HOMO–LUMO gap of the [EMIM][BF4] ion-pair. The bulk ab initio calculations are able to explain most of the features in the spectrum. However, DFT consistently lacks accuracy in the description of the top of the valence band. The dispersion corrected PBE calculation (PBE-D3) did offer very good agreement with the experimental structure, but the recently-developed vdW-DF functionals C09, optPBE, optB88 and CX were found to offer the best agreement in terms of the electronic structure.