Electron-Hole Separation Dynamics and Optoelectronic Properties of a PCE10:FOIC Blend.

Understanding charge separation dynamics in organic semiconductor blends is crucial for optimizing the performance of organic photovoltaic solar cells. In this study, the optoelectronic properties and charge separation dynamics of a PCE10:FOIC blend, by combining steady-state and time-resolved spectroscopies with high-level DFT calculations. Femtosecond transient absorption spectroscopy revealed a significant reduction of the exciton-exciton annihilation recombination rate in the acceptor when incorporated into the blend, compared to its pristine form.

Niobium Oxide Films with Variable Stoichiometry: Structure, Morphology, and Ultrafast Dynamics.

Niobium oxide can be stabilized in three distinct stoichiometries, each exhibiting unique physicochemical properties relevant to various technological applications. This study presents a novel procedure for fabricating niobium oxide films and tuning their stoichiometry among the three most stable oxide phases. Starting with a magnetron-sputtered film predominantly composed of NbO, its structure and stoichiometry are optimized through thermal treatment in an O/N flux.

A Culturally Humble Approach to Designing a Sports-Based Youth Development Program With African-Australian Community.

This article draws on the concept of cultural humility, to describe and analyze a decolonizing approach to co-designing a primary prevention basketball program for young African-Australian people in Melbourne, Australia. We explore the potential for genuine collaboration and power-sharing with a culturally diverse community through collaboratively developing the co-design process and resultant program design. This article highlights the central role of UBUNTU in the co-design process, prioritizing African ways of knowing, being, and doing within a Westernized social work and design context.

Excited state dynamics of Zn-salophen complexes.

Zn-salophen complexes are a promising class of fluorescent chemosensors for nucleotides and nucleic acids. We have investigated, by means of steady state UV-Vis, ultrafast transient absorption, fluorescence emission and time dependent density functional theory (TD-DFT) the behavior of the excited states of a salicylidene tetradentate Schiff base (Sal), its Zn(II) coordination compound (Zn-Sal) and the effect of the interaction between Zn-Sal and adenosine diphosphate (ADP). TD-DFT shows that the deactivation of the excited state of Sal occurs through torsional motion, due to its rotatable bonds and twistable angles.

Young Peoples' Construction of DIY Dirt Jumps in Melbourne, Australia, Throughout the Covid-19 Lockdowns.

Access to public space is critically important for young people, providing key opportunities for self-expression, independence, identity development and relationship building. The Covid-19 pandemic has profoundly affected how young people can engage with public spaces. In Melbourne, Australia, young people have experienced 262 days in lockdown, contributing to escalating anxiety and depression, social isolation, physical health impacts and increased exposure to family conflict and family violence.

Continuing the precedent: Financially disadvantaging young people in "unprecedented" COVID-19 times.

The COVID-19 pandemic is both a health and an economic crisis. Economically, lockdowns across Australia have devastated business and industry, creating immediate spikes in under- and unemployment. These impacts intersect with the precarious labour market of casualised and "gig" economy work, where young workers constitute an established and substantial group.

Ultrafast optical spectroscopy of semiconducting and plasmonic nanostructures and their hybrids.

The knowledge of the carrier dynamics in nanostructures is of fundamental importance for the development of (opto)electronic devices. This is true for semiconducting nanostructures as well as for plasmonic nanoparticles (NPs). Indeed, improvement of photocatalytic efficiencies by combining semiconductor and plasmonic nanostructures is one of the reasons why their ultrafast dynamics are intensively studied.

Ultrafast Formation of Small Polarons and the Optical Gap in CeO.

The ultrafast dynamics of excited states in cerium oxide are investigated to access the early moments of polaron formation, which can influence the photocatalytic functionality of the material. UV transient absorbance spectra of photoexcited CeO exhibit a bleaching of the band edge absorbance induced by the pump and a photoinduced absorbance feature assigned to Ce 4f → Ce 5d transitions. A blue shift of the spectral response of the photoinduced absorbance signal in the first picosecond after the pump excitation is attributed to the dynamical formation of small polarons with a characteristic time of 330 fs.

A Study of Photoinduced Coherent Vibrations in Gold-Nanorod Dispersions.

Upon photoexcitation with a femtosecond laser pulse, the plasmonic resonance of a nanorod can couple with coherent vibrational modes generating a regular oscillating pattern in the transient absorbance of the nanostructure. The dynamics of the plasmon resonances of these materials are probed through femtosecond transient absorption spectroscopy in the spectral region between 400 nm and 1600 nm. Whereas in the visible range the spectra are comparable with the findings reported in the literature, the analysis of the transient NIR spectra revealed that their oscillation frequencies vary with wavelength, resulting in a strong distortion of the transient features that can be related to the specific lengths distribution of the nanorods contained in the sample.

Plasmon-induced resonant effects on the optical properties of Ag-decorated ZnSe nanowires.

In this work we show how the optical properties of ZnSe nanowires are modified by the presence of Ag nanoparticles on the sidewalls of the ZnSe nanowires. In particular, we show that the low-temperature luminescence of the ZnSe nanowires changes its shape, enhancing the phonon replicas of impurity-related recombination and affecting rise and decay times of the transient absorption bleaching at room temperatures, with an increase of the former and a decrease of the latter. In contrast, the deposition of Au nanoparticles on ZnSe nanowires does not change the optical properties of the sample.

Whole-House Emission Rates and Loss Coefficients of Formaldehyde and Other Volatile Organic Compounds as a Function of the Air Change Rate.

Whole-house emission rates and indoor loss coefficients of formaldehyde and other volatile organic compounds (VOCs) were determined from continuous measurements inside a net-zero energy home at two different air change rates (ACHs). By turning the mechanical ventilation on and off, it was demonstrated that formaldehyde concentrations reach a steady state much more quickly than other VOCs, consistent with a significant indoor loss rate attributed to surface uptake. The first order loss coefficient for formaldehyde was 0.

NO Emissions From Two Agroecosystems: High Spatial Variability and Long Pulses Observed Using Static Chambers and the Flux-Gradient Technique.

With the addition of nitrogen (N), agricultural soils are the main anthropogenic source of NO, but high spatial and temporal variabilities make NO emissions difficult to characterize at the field scale. This study used flux-gradient measurements to continuously monitor NO emissions at two agricultural fields under different management regimes in the inland Pacific Northwest of Washington State, USA. Automated 16-chamber arrays were also deployed at each site; chamber monitoring results aided the interpretation of the flux gradient results.

A Fast Transient Absorption Study of Co(AcAc).

The study of transition metal coordination complexes has played a key role in establishing quantum chemistry concepts such as that of ligand field theory. Furthermore, the study of the dynamics of their excited states is of primary importance in determining the de-excitation path of electrons to tailor the electronic properties required for important technological applications. This work focuses on femtosecond transient absorption spectroscopy of Cobalt tris(acetylacetonate) (Co(AcAc)) in solution.

Highly efficient plasmon-mediated electron injection into cerium oxide from embedded silver nanoparticles.

The coupling with plasmonic metal nanoparticles (NPs) represents a promising opportunity to sensitize wide band gap oxides to visible light. The processes which come into play after the excitation of localized surface plasmon resonances (LSPRs) in the NPs largely determine the efficiency of the charge/energy transfer from the metal NP to the oxide. We report a study of plasmon-mediated energy transfer from mass-selected silver NPs into the cerium oxide matrix in which they are embedded.

Carrier dynamics in silicon nanowires studied via femtosecond transient optical spectroscopy from 1.1 to 3.5 eV.

We present femtosecond transient transmission (or absorbance) measurements in silicon nanowires in the energy range 1.1-3.5 eV, from below the indirect band-gap to above the direct band-gap.

Gold nanoparticles functionalized by rhodamine B isothiocyanate: A new tool to control plasmonic effects.

Gold nanoparticles with an average diameter of 10 nm, functionalized by the dye molecule rhodamine B isothiocyanate, have been synthesized. The resulting material has been extensively characterized both chemically, to investigate the bonding between the dye molecules and the nanoparticles, and physically, to understand the details of the aggregation induced by interaction between dye molecules on different nanoparticles. The plasmonic response of the system has been further characterized by measurement and theoretical simulation of the static UV-Vis extinction spectra of the aggregates produced following different synthesis procedures.

Soft X-ray absorption spectroscopy of Ar2 and ArNe dimers and small Ar clusters.

The X-ray absorption spectra (XAS) of Ar2 and ArNe dimers and small Ar clusters in the L2,3 region (244-252 eV) of the Ar atom have been recorded using synchrotron light and a combination of coincidence methods and kinetic energy discrimination of energetic ions. The absorption peaks in the spectra of the dimers and clusters were found to be shifted and broadened relative to the peaks in the spectrum of the Ar atom. In order to unambiguously relate these chemical shifts to the electronic structure of the core excited states in dimers, we performed ab initio calculations of the XAS spectra.

The Low Density Matter (LDM) beamline at FERMI: optical layout and first commissioning.

The Low Density Matter (LDM) beamline has been built as part of the FERMI free-electron laser (FEL) facility to serve the atomic, molecular and cluster physics community. After the commissioning phase, it received the first external users at the end of 2012. The design and characterization of the LDM photon transport system is described, detailing the optical components of the beamline.

Photofragmentation of halogenated pyrimidine molecules in the VUV range.

In the present work, we studied the photoinduced ion chemistry of the halogenated pyrimidines, a class of prototype radiosensitizing molecules, in the energy region 9-15 eV. The work was stimulated by previous studies on inner shell site-selective fragmentation of the pyrimidine molecule, which have shown that the fragmentation is governed by the population/formation of specific ionic states with a hole in valence orbitals, which in turn correlate to accessible dissociation limits. The combined experimental and theoretical study of the appearance energies of the main fragments provides information on the geometric structure of the products and on the role played by the specific halogen atom and the site of halogenation in the dissociation process.

Charge transfer and penning ionization of dopants in or on helium nanodroplets exposed to EUV radiation.

Helium nanodroplets are widely used as a cold, weakly interacting matrix for spectroscopy of embedded species. In this work, we excite or ionize doped He droplets using synchrotron radiation and study the effect onto the dopant atoms depending on their location inside the droplets (rare gases) or outside at the droplet surface (alkali metals). Using photoelectron-photoion coincidence imaging spectroscopy at variable photon energies (20-25 eV), we compare the rates of charge-transfer to Penning ionization of the dopants in the two cases.

Multimode resonant Auger scattering from the ethene molecule.

Resonant Auger spectra of ethene molecule have been measured with vibrational resolution at several excitation energies in the region of the C1s(-1)1b(2g)(π*) resonance. The main features observed in the experiment have been assigned and are accurately interpreted on the basis of ab initio multimode calculations. Theory explains the extended vibrational distribution of the resonant Auger spectra and its evolution as a function of the excitation energy by multimode excitation during the scattering process.

Competing channels in the thermal decomposition of azidoacetone studied by pyrolysis in combination with molecular beam mass spectrometric techniques.

The thermal decomposition of azidoacetone (CH3COCH2N3) was studied using a combined experimental and computational approach. Flash pyrolysis at a range of temperatures (296-1250 K) was used to induce thermal decomposition, and the resulting products were expanded into a molecular beam and subsequently analyzed using electron bombardment ionization coupled to a quadrupole mass spectrometer. The advantages of this technique are that the parent molecules spend a very short time in the pyrolysis zone (20-30 mus) and that the subsequent expansion permits the stabilization of thermal products that are not observable using conventional pyrolysis methods.