CHIMIA 2007, 6 1 ,No. 1 2 C himia 6 1(2007) 7 8 0 -7 8 6 © Sch w eiz e r i s c he C hemis c he G e s ells c h a f t ISSN 0009-42 9 3 P hot on C ollec t ion E ffi c ienc y of F l u o r e s c ent S ola r C ollec t o rsPatta r eey aKi ttidach ach a n, L eft e r i s Danos , T homa s J . J . M e y e r , N i c ola s A lder m a n, a nd T om Mar k v a rt* Abstract : P hot on c ollec t ion effic ienc y of flu o r e s c ent c ollec t o rs i s e x a mined e x per iment a lly a nd b y modelling, w i t h a v iewto a sse ss t he pot ent i a lof t his a ttract i v e s ola r ener g yte c hnology . T he edge flu o r e s c enc eof s ingle d y e c ollect o rs bas ed on R hoda mine 6 Gand C o u m a r in 540 A ,ma n u f actured b y a s imple f abr i cat ion t e c hnique, i s inv e stiga t ed in det a il. A nov el t e c hniquefo r det e r mina t ion of t he c ollec t ion effic ienc y i s p r e s ent ed bas ed on t he tra dit iona lmodel of flu o r e s c ent c ollec t o rs b ut e xtended t o a llowspec tra l a n a l ysi s . W e s howth a tthes e r e sul ts a g r ee w ell w i t hdi r e c t s ola r c ell mea surements. G ener a l c onc l usions a r ep r e s ent ed abo ut f u nda ment a ll o ss mec h a nis m s a nd abo ut t he r ole of r e-abs o r p t ion of flu o r e s c ent light . I t i ss how n t h a ts u b sta n t i a li mpr o v ements in c ollec t o r effic ienc y can b e m a de w i t h t he useofphot onic flu o r e s c enc e c onfinementra t herth a n b yto t a lin t e r n a l r eflec t ion.K e ywo r d s : F l u o r e s c ent c ollec t o rs ⋅ P hot on c ollec t ion effic ienc y ⋅ S ola r ener g y

The reactivity of carbon dioxide with vanadium(III) aryloxo complexes has been investigated. The formation of either carbon monoxide or incorporation into the ligand system with the ultimate formation of organic ester was observed depending on the overall electron donor ability of the ligand field. DFT calculations were carried out to investigate the proposed mechanism for carbon dioxide coordination and reduction.

The high pressure behavior of TaON was studied using a combination of Raman scattering, synchrotron X-ray diffraction, and X-ray absorption spectroscopy in diamond anvil cells to 70 GPa at ambient temperature. A Birch-Murnaghan equation of state fit for baddeleyite structured β-TaON indicates a high bulk modulus value K o =3284 GPa with K o '=4.3. EXAFS analysis of the high pressure XAS data provides additional information on changes in the Ta-(O,N) and Ta-Ta distances. Changes in the X-ray diffraction patterns and Raman spectra indicate onset of a pressure induced phase transition near 33 GPa. Our analysis indicates that the new phase has an orthorhombic cotunnitetype structure but that the phase transition may not be complete even by 70 GPa. Similar sluggish transformation kinetics are observed for the isostructural ZrO 2 phase. Analysis of compressibility data for the new cotunnite-type TaON phase indicate a very high bulk modulus K o ~ 370 GPa, close to the theoretically predicted value.

Treatment of divalent (ONNO)V(TMEDA) (1; ONNO=[2,4-Me -2-(OH)C H CH ] N(CH ) NMe ) with CO afforded [(ONNO)V] (μ-OH)(μ-formate) (2). Whereas the bridging hydroxo and formate groups both originated from CO , the H atoms present on the two residues were obtained through H-atom radical abstraction from the solvent. DFT calculations revealed an initially linear CO bonding mode, followed by deoxygenation, and highlighted a synergistic effect between the so-formed oxo group and an additional bridging CO residue in promoting radical behavior.