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We report a combined experimental and computational study of carbon dioxide activation at gas-phase Ho+ and HoO+ centres. Infrared action spectra of Ho(CO2)n+ and [HoO(CO2)n]+ ion–molecule complexes have been recorded in the spectral region 1700–2400 cm−1 and assigned by comparison with simulated spectra of energetically low-lying structures determined by density functional theory. Little by way of activation is observed in Ho(CO2)n+ complexes with CO2 binding end-on to the Ho+ ion. By contrast, all [HoO(CO2)n]+ complexes n ≥ 3 show unambiguous evidence for formation of a carbonate radical anion moiety,. The signature of this structure, a new vibrational band observed around 1840 cm−1 for n = 3, continues to red-shift monotonically with each successive CO2 ligand binding with net charge transfer from the ligand rather than the metal centre. [ABSTRACT FROM AUTHOR]

Over the past few decades, extrinsic tracking devices (e.g., radio transmitters, GPS loggers, satellite transmitters, geolocators) have been widely used to study wildlife movement and other demographic parameters. Remote tracking and monitoring technology is continually advancing, and its use by researchers is becoming more widespread. Minimizing any potential impacts of tracking devices on focal species is of upmost importance in order to ensure and promote animal welfare and reliable scientific information. Many researchers aim to understand any potential short- or long-term impacts of remote tracking, and to develop methods that support the responsible and safe tagging of birds (e.g., Geen et al. 2019). As tracking projects become more mainstream, it is critical that banders and researchers stay up to date and contribute to current base of knowledge on the topic. This review summarizes available research demonstrating the impacts of attaching a variety of tracking devices to birds in order to guide and promote minimally invasive methods of deploying tracking devices, and to highlight the need for continued study of the effects of devices and attachment methods on bird welfare. [ABSTRACT FROM AUTHOR]

The application of evanescent wave cavity ring-down spectroscopy (EW-CRDS) in monitoring electrogenerated species within a thin-layer electrochemical cell is demonstrated. In the proof-of-concept experiments described, ferricyanide, Fe[(CN).sub.6.sup.3-], was produced by the transport-limited oxidation of ferrocyanide, Fe[(CN).sub.6.sup.4-], in a thin-layer solution cell (25-250 [micro]m) formed between an electrode and the hypotenuse of a fused-silica prism. The prism constituted one element of a high-finesse optical cavity arranged in a triangular ring geometry with light being totally internally reflected at the silica/solution interface. The cavity was pumped with the output (~417 nm) of a single-mode external cavity diode laser, which was continuously scanned across the cavity modes. The presence of electrogenerated ferricyanide within the resulting evanescent field, beyond the optical interface, was detected by the enhanced loss of light trapped within the cavity, as measured by the characteristic cavity ring down. In this way, the EW-CRDS technique is sensitive to absorption in only the first few hundred nanometers of solution above the silica surface. The cavity ring-down response accompanying both cyclic voltammetric and step potential chronoamperometry experiments at a variety of electrode-surface distances is presented, and the results are shown to be well reproduced in modeling by finite element methods. The studies herein thus provide a foundation for further applications of EW-CRDS combined with electrochemistry.

Even though the interaction of a <1 mT magnetic field with an electron spin is less than a millionth of the thermal energy at room temperature (kBT), it still can have a profound effect on the quantum yields of radical pair reactions. We present a study of the effects of sub-millitesla magnetic fields on the photoreaction of flavin mononucleotide with ascorbic acid. Direct control of the reaction pathway is achieved by varying the rate of electron transfer from ascorbic acid to the photo-excited flavin. At pH 7.0, we verify the theoretical prediction that, apart from a sign change, the form of the magnetic field effect is independent of the initial spin configuration of the radical pair. The data agree well with model calculations based on a Green's function approach that allows multinuclear spin systems to be treated including the diffusive motion of the radicals, their spin-selective recombination reactions, and the effects of the inter-radical exchange interaction. The protonation states of the radicals are uniquely determined from the form of the magnetic field-dependence. At pH 3.0, the effects of two chemically distinct radical pair complexes combine to produce a pronounced response to ~500 μT magnetic fields. These findings are relevant to the magnetic responses of cryptochromes (flavin-containing proteins proposed as magnetoreceptors in birds) and may aid the evaluation of effects of weak magnetic fields on other biologically relevant electron transfer processes. [ABSTRACT FROM AUTHOR]

The near ultraviolet photodissociation dynamics of silver atom-rare gas dimers have been studied by velocity map imaging. Ag-RG (RG = Ar, Kr, Xe) species generated by laser ablation are excited in the region of the C ((²Σ+)←X (²Σ+) continuum leading to direct, near-threshold dissociation generating Ag* (²P3/2) + RG¹S0) products. Images recorded at excitation wavelengths throughout the C (²Σ+)←X (²Σ+) continuum, coupled with known atomic energy levels, permit determination of the ground X (²Σ+) state dissociation energies of 85.9 ± 23.4 cm-1 (Ag-Ar), 149.3 ± 22.4 cm-1 (Ag-Kr), and 256.3 ± 16.0 cm-1 (Ag-Xe). Three additional photolysis processes, each yielding Ag atom photoproducts, are observed in the same spectral region. Two of these are markedly enhanced in intensity upon seeding the molecular beam with nitrous oxide, and are assigned to photodissociation of AgO at the two-photon level. These features yield an improved ground state dissociation energy for AgO of 15 965 ± 81 cm-1, which is in good agreement with high level calculations. The third process results in Ag atom fragments whose kinetic energy shows anomalously weak photon energy dependence and is assigned tentatively to dissociative ionization of the silver dimer Ag2. [ABSTRACT FROM AUTHOR]

Infrared multiple-photon dissociation spectroscopy has been applied to study Ptn(N2O)+ (n = 1–8) clusters which represent entrance-channel complexes on the reactive potential energy surface for nitrous oxide decomposition on platinum. Comparison of spectra recorded in the spectral region 950 cm−1 to 2400 cm−1 with those simulated for energetically low-lying structures from density functional theory shows a clear preference for molecular binding via the terminal N atom, though evidence of O-binding is observed for some cluster sizes. Enhanced reactivity of Ptn+n ≥ 6 clusters towards N2O is reflected in the calculated reactive potential energy surfaces and, uniquely in the size range studied, Pt6(N2O)+ proved impossible to form in significant number density even with cryogenic cooling of the cluster source. Infrared-driven N2O decomposition, resulting in the formation of cluster oxides, PtnO+, is observed following vibrational excitation of several Ptn(N2O)+ complexes. [ABSTRACT FROM AUTHOR]

Technologies for remotely observing animal movements have advanced rapidly in the past decade. In recent years, Australia has invested in an Integrated Marine Ocean Tracking (IMOS) system, a land ecosystem observatory (TERN), and an Australian Acoustic Observatory (A2O), but has not established movement tracking systems for individual terrestrial animals across land and along coastlines. Here, we make the case that the Motus Wildlife Tracking System, an open-source, rapidly expanding cooperative automated radio-tracking global network (Motus, https://motus.org) provides an unprecedented opportunity to build an affordable and proven infrastructure that will boost wildlife biology research and connect Australian researchers domestically and with international wildlife research. We briefly describe the system conceptually and technologically, then present the unique strengths of Motus, how Motus can complement and expand existing and emerging animal tracking systems, and how the Motus framework provides a much-needed central repository and impetus for archiving and sharing animal telemetry data. We propose ways to overcome the unique challenges posed by Australia's ecological attributes and the size of its scientific community. Open source, inherently cooperative and flexible, Motus provides a unique opportunity to leverage individual research effort into a larger collaborative achievement, thereby expanding the scale and scope of individual projects, while maximising the outcomes of scant research and conservation funding. [ABSTRACT FROM AUTHOR]

The dissociative ionization dynamics of excited electronic states of the xenon dimer, Xe2, have been studied using velocity map ion imaging (VMI). A one-colour, (2+1) resonant excitation scheme was employed to first excite and then ionize selected vibrational levels of the Xe2 6p 2[1/2]0 0g+ Rydberg state. Cationic fragments were then detected by the VMI. The data provide an outstanding example of the reflection principle in photodissociation with the full nodal structure of the Rydberg state wavefunctions clearly observed in the final Xe+ kinetic energy distributions without the need for scanning the excitation energy. Fitting of the observed distributions provides detailed and precise information on the form of the Xe2+ I(1/2g) potential energy curve involved which is in excellent agreement with the results of photoelectron imaging studies [Shubert and Pratt, J. Chem. Phys. 134, 044315 (2011) ]. Furthermore, the anisotropy of the product angular distributions yields information on the evolution of the electronic character of the ionic state with internuclear separation, R. The combination of the nature of dissociative ionization and the extent of the bound state wavefunctions provide information over an unusually wide range of internuclear separation R (ΔR > 0.75 Å). This would normally require scanning over a considerable energy region but is obtained in these studies at a fixed excitation energy. [ABSTRACT FROM AUTHOR]