Rationalizing In Situ Active Repair in Hydrogen Evolution Photocatalysis via Non-Invasive Raman Spectroscopy.

Currently, most photosensitizers and catalysts used in the field of artificial photosynthesis are still based on rare earth metals and should thus be utilized as efficiently and economically as possible. While repair of an inactivated catalyst is a potential mitigation strategy, this remains a challenge. State-of-the-art methods are crucial for characterizing reaction products during photocatalysis and repair, and are currently based on invasive analysis techniques limiting real-time access to the involved mechanisms. Herein, we use an innovative in situ technique for detecting both initially evolved hydrogen and after active repair via advanced non-invasive rotational Raman spectroscopy. This facilitates unprecedently accurate monitoring of gaseous reaction products and insight into the mechanism of active repair during light-driven catalysis enabling the identification of relevant mechanistic details along with innovative repair strategies.

Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. I. Structures and Thermal Effects.

Molecular complexes between glycolic acid and nitrogen were studied in a low-temperature argon matrix with FTIR spectroscopy, and supported by MP2 and BLYPD3 calculations. The calculations indicate 11 and 10 stable complex structures at the MP2 and BLYPD3 levels of theories, respectively. However, only one hydrogen-bonded complex structure involving the most stable SSC conformer of glycolic acid was found experimentally, where the nitrogen molecule is bound with the carboxylic OH group of the SSC conformer. The complex shows a rich site structure variation upon deposition of the matrix in different temperatures and upon annealing experiments, which provide interesting prospects for site-selective chemistry.

Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II. Vibrational Overtone Excitations.

Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N2 complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra. Both position and intensity of new absorptions appeared to be highly sensitive on the wavelength of radiation used, as well as on the annealing of the matrix. Based on theoretical calculations at different levels of theory, an assignment of the observed bands is proposed and discussed.

Finnish NGOs promoting health equity in the context of welfare economy.

Health inequality is a national challenge in Finland. The WHO global strategy of Health for All implies that all people should have an equal opportunity to develop and maintain their health through fair and just access to health resources. This article examines the role of Finnish Non-Governmental Organizations (NGO) in strengthening the health equity. The article presents the strategy and specific criteria constructed by the NGOs to promote health equity in society. The health equity criteria and welfare economy strategy are combined to a framework which NGOs can utilize in their work to promote health equity. The welfare economy strategy describes the important issues that NGOs have to address when working towards a specific societal goal, in this case equity. The health equity criteria in turn are an instrument for the practical implementation of the preconditions of equity.

Visible light-driven chemistry of oxalic acid in solid argon, probed by Raman spectroscopy.

High-overtone induced chemistry of oxalic acid (OA) isolated in a low-temperature argon matrix was investigated using Raman spectroscopy. The Raman spectra of three conformers of OA are presented and discussed. Upon excitation of high overtone combination bands by 532 nm irradiation of the lowest energy cTc structure, the isomerization and unimolecular decomposition of OA were observed. Dissociation was induced presumably by absorption into the 5A(g) + B(u) vibrational state of the OH stretching mode of cTc. The photodecomposition leads to the formation of CO, CO(2), and H(2)O products. The experimental observations were supported by computational studies and vibrational anharmonic calculations.

Electronic spectroscopy of I(2)-Xe complexes in solid Krypton.

In the present work, we have studied ion-pair states of matrix-isolated I(2) with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I(2)-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I(2) with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm(-1) from the X → D transition of I(2). Observed redshift can be explained by symmetry breaking of ion-pair states within the I(2)-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I(2) ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I(2) dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.

Photolysis of HCOOH monomer and dimer in solid argon: Raman characterization of in situ formed molecular complexes.

Raman spectroscopy combined with the matrix isolation technique was employed to study the 193-nm photodecomposition products of formic acid in an argon matrix. The Raman-active fundamentals belonging to the CO(2) + H(2) and CO + H(2)O photoproducts were assigned. Also, bands due to Fermi resonance between the stretching vibration (nu(1)) and the overtone of the bending mode (2nu(2)) of CO(2) were identified. Both ortho- and para-H(2) molecules were identified from their rotational lines S(0)(1) and S(0)(0), respectively. These bands appeared upon matrix annealing as well as after prolonged photolysis. Additionally, photolysis of FA dimers produces oxalic acid and its secondary photoproducts, CO(2) + CO + H(2)O. All experimental studies were supported by ab initio calculations.

Investigating isomerization reactions in solid state by using simultaneous high overtone pumping and Raman detection.

Formation of the unstable cis-formic acid in solid argon matrix is induced by direct excitation of the 6<--0 transition of the nu(OH) vibration of the trans-formic acid. The experiment utilizes strongly focused laser beam that produces relatively high isomerization rate despite the low cross section of the absorption. Raman spectroscopy in a backscattering geometry is used for detection of the reactants and the products. This experimental arrangement allow us to use the same laser source for simultaneous pumping and Raman excitation, and it also guarantees that the excited and probed volumes overlap. The presented method has a high potential for solid state investigations of chemical reactions on the ground electronic state.

Structure and matrix isolation infrared spectrum of formyl fluoride dimer: blue-shift of the C-H stretching frequency.

Infrared spectroscopy (IR) of formyl fluoride (HCOF) dimer is studied in low-temperature argon and krypton matrixes. New IR absorptions, ca. 17 cm(-1) blue shifted from the monomer C-H stretching fundamental, are assigned to the HCOF dimer. The MP2/6-311++G calculations were utilized to define structures and harmonic frequencies of various HCOF dimers. Among the four optimized structures, the dimer having two C-H...O hydrogen bonds possesses strongest intermolecular bonding. The calculated harmonic frequencies of this dimer structure are shifted from the monomer similarly as observed in the experiment. Thus, we suggest that the experimentally observed blue shifted C-H bands belong to the dimer with two C-H...O hydrogen bonds. This observation includes the HCOF dimer to the class of hydrogen bonded complexes showing blue shift in their vibrational energies.

Photodissociation of formyl fluoride in rare gas matrixes.

Photodissociation of formyl fluoride (HCOF) is studied in Ar, Kr, and Xe matrixes at 248 and 193 nm excitation by following spectral changes in the infrared absorption spectra. In all matrixes, the main photodissociation products are CO/HF species, including CO-HF and OC-HF complexes and thermally unstable CO/HF species (a distorted CO/HF complex or a reaction intermediate), which indicate negligible cage exit of atoms produced via the C-F and C-H bond cleavage channels. However, the observation of traces of H, F, CO, CO(2), F(2)CO, FCO, and HRg(2)(+) (Rg = Kr or Xe) in Kr and Xe matrixes would imply some importance of other reaction channels too. The analysis of the decay curves of the precursor shows that dissociation efficiency of HCOF increases as Ar < Kr < Xe, the difference being the factor of 10 between Ar and Xe. Moreover, HCOF dissociates 20-50 times faster at 193 nm compared to 248 nm. Interestingly, whereas the CO/HF species are stable with respect to photolysis in Ar, they photobleach in Kr and Xe matrixes at 248 and 193 nm, even though the first excited states of CO and HF are not energetically accessible with 193 and 248 nm photons. In krypton matrix, the photodissociation of CO/HF species at 248 nm is observed to be a single photon process. Quantum chemical calculations of electronic excitation energies of CO-HF and OC-HF complexes show that the electronic states of HF and CO mostly retain their diatomic nature in the pair. This clearly demonstrates that photodissociation of CO/HF complexes is promoted by the surrounding rare gas lattice.