Energy Loss Processes Research Articles

Investigating limitations of biohybrid photoelectrode using synchronized spectroelectrochemistry.

The challenge in optimizing biohybrid photoelectrodes lies in identifying kinetic bottleneck and energy loss of photoinduced electron transfer. In this issue of Joule, Friebe's group describes a method for synchronized spectroscopic and electrochemical measurements of biophotoelectrode in operando, which indicates the electron transfer bottleneck steps and the energy loss processes.

Molecular Design of A-D-A Electron Acceptors Towards Low Energy Loss for Organic Solar Cells.

Low energy loss is a prerequisite for organic solar cells to achieve high photovoltaic efficiency. Electron-vibration coupling (i. e., intramolecular reorganization energy) plays a crucial role in the photoelectrical conversion and energy loss processes. In this Concept article, we summarize our recent theoretical advances on revealing the energy loss mechanisms at the molecular level of A-D-A electron acceptors. We underline the importance of electron-vibration couplings on reducing the energy loss and describe the effective molecular design strategies towards low energy loss through decreasing the electron-vibration couplings.

Ionization of inner T Tauri star discs: effects ofin situenergetic particles produced by strong magnetic reconnection events

ABSTRACTMagnetic reconnection is one of the major particle acceleration processes in space and astrophysical plasmas. Low-energy supra-thermal particles emitted by magnetic reconnection are a source of ionization for circumstellar discs, influencing their chemical, thermal, and dynamical evolution. The aim of this work is to propose a first investigation to evaluate how energetic particles can propagate in the circumstellar disc of a T Tauri star and how they affect the ionization rate of the disc plasma. To that end, we have collected experimental and theoretical cross sections for the production of H+, H$_2^+$, and He+ by electrons and protons. Starting from theoretical injection spectra of protons and electrons emitted during magnetic reconnection events, we have calculated the propagated spectra in the circumstellar disc considering the relevant energy loss processes. We have considered fluxes of energetic particles with different spectral indices and different disc magnetic configurations, generated at different positions from the star considering the physical properties of the flares as deduced from the observations obtained by the Chandra Orion Ultra Deep point source catalogue. We have then computed the ionization rates for a disc whose structure has been calculated with the radiation thermo-chemical code prodimo. We find that energetic particles are potentially a very strong source of local ionization with ionization rates exceeding by several orders of magnitude the contribution due to X-rays, stellar energetic particles, and radioactivity in the inner disc.

Cosmic-ray electron transport in the galaxy M 51

Context. Indirect observations of the cosmic-ray electron (CRE) distribution via synchrotron emission is crucial for deepening the understanding of the CRE transport in the interstellar medium, and in investigating the role of galactic outflows. Aims. In this paper, we quantify the contribution of diffusion- and advection-dominated transport of CREs in the galaxy M51 considering relevant energy loss processes. Methods. We used recent measurement from M 51 that allow for the derivation of the diffusion coefficient, the star formation rate, and the magnetic field strength. With this input, we solved the 3D transport equation numerically including the spatial dependence as provided by the measurements, using the open-source transport framework CRPropa (v3.1). We included 3D transport (diffusion and advection), and the relevant loss processes. Results. We find that the data can be described well with the parameters from recent measurements. For the best fit, it is required that the wind velocity, following from the observed star formation rate, must be decreased by a factor of 5. We find a model in which the inner galaxy is dominated by advective escape and the outer galaxy is composed by both diffusion and advection. Conclusions. Three-dimensional modelling of cosmic-ray transport in the face-on galaxy M51 allows for conclusions about the strength of the outflow of such galaxies by quantifying the need for a wind in the description of the cosmic-ray signatures. This opens up the possibility of investigating galactic winds in face-on galaxies in general.

Shadowing effects in the diffractive scattering of virtual photons on nuclei and its interference with the process of bremsstrahlung

In cosmic ray physics and high-energy neutrino astronomy, muons are ubiquitous. Due to their slow energy loss and consequently large range at high energies, the correct simulation of their transport through matter is especially important for underground experiments. The dominant energy loss processes are ionization and at higher energies pair production, bremsstrahlung and inelastic interaction with nuclei. A muon energy loss process, which has hitherto been neglected in such simulations, is the diffractive scattering of virtual photons on nuclei. As the elastic channel of this process has the same final state as the bremsstrahlung process (mu + A rightarrow mu + A + gamma ), an interference term arises, whose sign depends on the charge of the lepton. It is found that the contribution of this process was overestimated in earlier works and is significantly affected by shadowing.

Influence of air and water vapor on EEDF, plasma parameters, and the main RONS in atmospheric pressure low temperature helium plasmas: Global model approach

A zero-dimensional global model is developed with an aim to study the influence of air and water vapor on an electron energy distribution function, electron density, and temperature as well as on the chemical composition of atmospheric pressure helium plasmas, with special focus on the main reactive oxygen and nitrogen species important for applications of low temperature plasmas. The main channels for the production and consumption of electrons and electron energy gain and loss are examined by a global model based on a parametric study with variations of the mole fractions of air and water vapor. The calculations are done for 100, 1000, and 10 000 ppm of air in plasma, and for each of these values, the content of water vapor is taken to be 100, 1000, 2000, …, to 10 000 ppm. The variations of the most important production and consumption processes for reactive oxygen and nitrogen species are analyzed in detail. According to the results presented in this paper, water vapor highly contributes to electronegativity of the plasma through pronounced attachment of electrons, which then leads to an increase in electron temperature. For high water vapor content, vibrational excitations of water molecules are one of the main electron energy loss processes, leading to a further effect on the plasma composition. Water decreases concentrations of atomic oxygen, nitrogen, and ozone, while there is an increase in nitrogen oxide, OH, H2O2, and HO2 concentrations. Cross-sectional data for electron scattering on ground and excited state neutrals are mainly taken from the Quantemol-DB database.

A New Method of Simulation of Cosmic-ray Ensembles Initiated by Synchrotron Radiation

Cosmic rays interact with fields and background radiation as they propagate in space, producing particle cascades of various sizes, shapes and constituents. The potential observation of at least parts of such phenomena, referred to as cosmic-ray ensembles (CRE), from Earth would open a new channel of cosmic-ray investigation, since it might be a manifestation of fundamental symmetries of nature. Research dedicated to CRE is one of the main scientific objectives of the Cosmic-Ray Extremely Distributed Observatory (CREDO) Collaboration, and with this article we address one of the cornerstones of the relevant scientific program: the simulation method dedicated to CRE studies. Here we focus on CRE resulting from synchrotron radiation by high energy electrons as one of the most prevalent energy loss processes. Providing the example of simulation output analysis, we demonstrate the advantages of our approach as well as discuss the possibility of generalization of current research.

Swift Heavy Ion-Induced Reactivity and Surface Modifications in Indium Thin Films.

As an energetic ion traverses a target material, it loses its energy through the processes of electronic energy loss (Se) and nuclear energy loss (Sn). Controlled swift heavy ion (SHI) irradiation on solid targets produces its effects through both of these mechanisms, as a consequence of which modifications occur in the structure, surface morphology, and magnetic and optical properties, apart from ion implantation and ion-induced reactivity. A systematic investigation of these effects can be useful in developing standard protocols for creating desired effects in materials using specific ion beams. In this study, indium films of thickness 25 nm were deposited on silicon substrates and were subjected to 100 MeV O7+ and 100 MeV Si7+ ion irradiation, with the fluences varying from 1 × 1011 to 1 × 1013 ions/cm2. The pristine and SHI-irradiated films were then characterized using glancing incidence X-ray diffraction (GIXRD), Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The motive was to identify the effects of irradiation with different ion species having large variations in electronic and nuclear energy losses. While the RBS results suggest that sputtering is extremely low and that there are no major changes in the film composition due to ion beam-induced mixing, the GIXRD analysis indicates that increasing the ion fluence reduces the crystallinity of the film for both the ions. Ion beam irradiation with O7+ ions, however, results in beam-induced reactivity, as the GIXRD scan shows characteristic peaks from indium oxide (In2O3), which become the predominant peaks at the highest fluence used here. Si7+ ion irradiation results in a narrowing of the particle size distribution on the surface, with no evidence of reactivity. SEM results indicate fusion and fragmentation of grains with the increase in the ion fluences, and AFM images reveal an increase in the surface roughness of a few percent when irradiated with both 100 MeV O7+ and 100 MeV Si7+ ions.

First principle studies on properties of silicon-vacancy related defects in amorphous silica

The non-bridging oxygen hole center (NBOHC) can decrease the transmission efficiency of the amorphous silica (α-SiO2) material. In radiation environments, the NBOHC can be produced by both the electronic (Se) and the nuclear (Sn) energy loss processes of the radiations. The Se-related formation channels of NBOHC have been well characterized. The Sn can produce isolated silicon vacancies within α-SiO2 by knocking out silicon atoms. With first principle calculations, this work investigates the characteristics of the silicon-vacancy defective α-SiO2 cells, including atomic configuration, electronic density of state and optical absorption coefficient. The stable states of the silicon vacancy defects suggest a direct and an indirect Sn-related formation channels for NBOHC. The silicon vacancy has two stable configurations, i.e., the case I contains two NBOHC along with a peroxy linkage (POL), and the case II has two POL. Thereafter, the Se can promote the transition from POL to NBOHC.

Mechanistic insights into ion-beam induced reduction of graphene oxide: An experimental and theoretical study

Interest in graphene oxide (GO) due to its controllable and adjustable properties has been increasing, especially in the field of electronic and electrochemical charge storage devices. Hence, the modification of surface chemistry and structure of GO can be outlined as crucial for achieving the preferable properties. In this study, we have investigated the influence of 15 keV proton-beam irradiation on GO structure and surface chemistry. The results obtained by Raman spectroscopy, Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were complemented with theoretical ones, obtained by using density functional theory (DFT), semi-empirical (SE) calculations and inelastic thermal spike (iTS) model. The FTIR and XPS results showed that proton irradiation partially reduces the GO with the preferential removal of the alkoxy and epoxy groups. Also, we identified a clear linear relation between the decresase of oxygen content and the decrease of ID/IG ratio i.e. increasing disorder of GO structure. The SE and DFT calculations highlighted a reduction of GO as a single- or multi-step process depending on the type of basal-plane or edge oxygen group. Dynamic SE calculations revealed that for kinetic energy of hydrogen below 1.5 eV the reduction is chemically driven, while at energies higher than 20 eV, the reduction of GO is a result of physical processes. iTS results showed that increase of temperature might contribute to reduction of GO via desorption of epoxy and alcoxy groups, as the least thermally stable groups (T ∼200 °C). The results of this work emphasize the capabilities ion beam irradiation for gradual modification of surface chemistry and structural properties of GO by providing more information about the mechanisms of hydrogen interaction with individual groups, interplay between defect creation, oxygen content and accompaning effects of ion energy loss processes.

Monte Carlo simulations of the electron — gas interactions in the KATRIN experiment

At the KATRIN experiment, the electron antineutrino mass is inferred from the shape of the β-decay spectrum of tritium. Important systematic effects in the Windowless Gaseous Tritium Source (WGTS) of the experiment include the energy loss by electron scattering, and the extended starting potential. In the WGTS, primary high-energy electrons from β-decay produce an extended secondary spectrum of electrons through various atomic and molecular processes including ionization, recombination, cluster formation and scattering. In addition to providing data essential to the simulation of energy loss processes, the electron spectrum also provides information important in the simulation of plasma processes. These simulations will then provide an insight on the starting potential. Here, a Monte Carlo approach is used to model the electron spectrum in the source for a given magnetic and electric field configuration. The spectrum is evaluated at different positions within the WGTS, which allows for a direct analysis of the spectrum close to the rear wall and detector end of the experiment. Alongside electrons, also ions are tracked by the simulation, resulting in a full description of the currents in the source.

QUEELS: Software to calculate the energy loss processes in TEELS, REELS, XPS and AES including effects of the core hole

We present the user‐friendly and freely available software package QUEELS (QUantitative analysis of Electron Energy Losses at Surfaces) that allows to calculate effective inelastic scattering cross sections within the dielectric response description, for swift electrons travelling nearby surfaces in several environments. We briefly describe the underlying theoretical models and illustrate its use to evaluate the distribution of energy losses taking place in electron spectroscopies like transmission electron energy loss spectroscopy (TEELS), X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS), which are widely used for material analysis. This includes the intrinsic excitations due to the core hole in XPS and AES.

Tunable Lifetime and Nonlinearity in Two Dimensional Materials Plasmonic-Photonic Absorber.

We investigate a framework of local field, quality factor and lifetime for tunable graphene nanoribbon plasmonic-photonic absorbers and study the second order and third order nonlinear optical response of surface plasmons. The energy exchange of plasmonic-photonic absorber occurs in two main ways: one way is the decay process of intrinsic loss for each resonant mode and another is the decay process of energy loss between graphene surface plasmon (GSP) mode and the external light field. The quality factor and lifetime of the plasmonic-photonic absorber can be obtained with using the coupled mode theory (CMT) and finite difference time domain (FDTD) method, which are effectively tunable with changing Fermi energy, carrier mobility and superstrate refractive index. The evolutions of total energy and lifetime of GSP are also shown, which are helpful for the study of micro processes in a two-dimensional material plasmonic-photonic absorber. The strongly localized fundamental field induces a desired increase of second harmonic (SH) wave and third harmonic (TH) wave. The manipulation of the quality factor and lifetime of the GSP makes graphene an excellent platform for tunable two-dimensional material plasmonic-photonic devices to realize the active control of the photoelectric/photothermal energy conversion process and higher harmonic generation.

Rates and Yields of Unimolecular Reactions Producing Highly Oxidized Peroxy Radicals in the OH-Induced Autoxidation of α-Pinene, β-Pinene, and Limonene.

Recent ambient atmospheric measurements have detected highly oxygenated organic molecules (HOMs) at many sites and are a consequence of autoxidation processes occurring at ambient temperatures. Monoterpenes in particular have a propensity to autoxidize although they exhibit a wide range of HOM yields, which may be due to a variety of reasons including reactions with different oxidants like OH and O3, differing hydrogen (H) atom transfer or peroxy radical cyclization rates, numbers of available reaction pathways, and/or energy loss processes for activated HO-monoterpene or O3-monoterpene adducts. In this work, the autoxidation mechanisms of (+)-α-pinene, (+)-β-pinene, and (+)-limonene following initial OH oxidation and three successive O2 additions are examined using density functional theory (DFT) to understand what accounts for the disparity. Rates of different potential autoxidation pathways initiated by OH addition or abstraction reactions are quantified using transition-state theory (TST) and master equation approaches using the lowest-energy conformers. OH abstraction reactions do not appreciably influence HOM production in the pinenes and limit autoxidation for limonene because the subsequent autoxidation reactions are slow while OH addition reactions are found to be the main route to HOMs for all three monoterpenes. Generally, faster autoxidation rates are computed in later unimolecular reactions that produce RO7 radicals after OH addition (∼10 s-1 or greater) than rates for RO5 peroxy radical production (0.2-7 s-1). Mechanistic pathways that form RO7 peroxy radicals are similar for all three monoterpenes with a particular bicyclo RO7 radical involving a five-membered peroxide ring being favored for all three monoterpenes. The molar yields of RO7 radicals are 4.6% (+10.0/-2.4), 3.8% (+9.1/-2.6), and 7.6% (+13.1/-4.9) for α-pinene, β-pinene, and limonene, respectively, at 298 K and 1 ppb of NO and only significantly decline at NO concentrations exceeding 10 ppb. The higher yield for limonene relative to the pinenes is predominantly a consequence of the initial oxidation step: OH adducts of the bicyclic pinenes have to use the excess energy after OH addition to break one of the rings and make the molecule more flexible for autoxidation although this process is inefficient, while one of the prominent OH adducts for monocyclic limonene does not have to do this and may add O2 immediately before autoxidizing further. These insights may be used to guide a better representation of these processes in atmospheric models because they affect particulate matter (PM), NOx, and ozone concentrations via enhanced production of low-volatility species, less early-generation NOx cycling, and altered organic nitrate production.

Investigations of microscopic mechanisms in exciplex-based devices with isomers of mCBP and CBP as donors via magneto-electroluminescence

The mCBP and CBP are two kinds of isomers containing carbazole groups and often used as the device hosts for fluorescence and phosphorescence emission. However, there are little studies on the microscopic mechanisms of exciplex-type devices based on mCBP or CBP. In this paper, the isomers of mCBP and CBP are used as donors and the PO-T2T is selected as an acceptor. The two kinds of exciplex-based devices are fabricated according to a mass ratio of 1∶1, which are respectively referred to as device 1 (Dev. 1) and device 2 (Dev. 2). Their magneto-electroluminescence (MEL) curves are measured at different working temperatures and various injection currents. It is found that the low field effects of the MEL curves from Dev. 1 are dominated by the <i>B</i>-mediated reverse intersystem crossing (RISC) process at room temperature, and as the operational temperature decreases, the MEL line-shapes change gradually from RISC to the intersystem crossing (ISC) process. Conversely, the low field effects of the MEL curves of Dev. 2 are governed by the <i>B</i>-mediated ISC process at room temperature, and the ISC process first weakens then strengthens with temperature decreasing. The high field effects of the MEL curves of Dev. 1 and Dev. 2 are both dominated by the <i>B</i>-mediated triplet-charge annihilation (TQA) process at room temperature, but those of Dev. 2 at 20 K present the <i>B</i>-mediated triplet-triplet annihilation (TTA) process. The completely opposite low-field line-shapes of MEL traces from Dev. 1 and Dev. 2 can be attributed to their different structures of mCBP and CBP, which lead to the higher and lower triplet state exciton energy, respectively. The higher triplet exciton energy of the mCBP donor causes the triplet exciplex energy to be confined effectively, which promotes the RISC process (EX<sub>1</sub> ← EX<sub>3</sub>) in Dev.1. Contrarily, the lower triplet exciton energy of the CBP donor causes the triplet exciplex to experience an energy loss process (EX<sub>3</sub> → T<sub>1</sub>, CBP) , resulting in the suppressed RISC process in Dev. 2. Consequently, the overlapped effects of the ISC process of polaron pairs and the RISC process of exciplex in Dev. 2 under the action of external magnetic field display the ISC-determined process at room temperature. Moreover, the temperature-dependent change in the microscopic process of Dev. 1 such as the conversion from RISC to ISC is because decreasing temperature is not conducive to the occurrence of the RISC process of exciplex states due to its endothermic property. The low-temperature TTA process occurring in Dev. 2 is due to the suppressed energy loss process of triplet exciplex via the Dexter energy transfer from the triplet exciplex to the triplet exciton of CBP donor. In addition, when the mass ratio of mCBP donor to PO-T2T acceptor varies from 1∶4 to 1∶1 to 4∶1, the RISC process of MEL curves of devices turns stronger and stronger, which is because the devices tend more to balance, favoring the RISC process. A higher external quantum efficiency is obtained in the mCBP:PO-T2T host than in the CBP:PO-T2T host when fluorescent guest material of TBRb is used as a dopant in these two exciplex-based devices, which verifies the importance of the effective confinement of triplet exciplex energy in improving the luminescence efficiency. Note that via the MEL detection technology, the current- and temperature-dependent microscopic processes and their reasonable interpretations and device performances from exciplex-based devices with the isomers of mCBP and CBP as donors have not been reported in the literature. This work provides experimental and theoretical references for fabricating the high-efficiency exciplex-based organic light-emitting devices.

Impact of neutral gas puffing on the divertor power exhaust and particle control in GAMMA 10/PDX by the LINDA‐KNMC code

AbstractThis paper numerically investigates the impact of neutral gas puffing on the divertor power exhaust and particle control in GAMMA 10/PDX applying the plasma fluid code LINDA and the kinetic neutral code KMNC. The LINDA code is applied to GAMMA 10/PDX plasmas for understanding the physics of detachment and energy loss processes. The LINDA code is coupled with a Monte–Carlo neutral code for describing the hydrogen (H and H2) neutral particles. The plasma ion temperature (Ti) is reduced towards the target plate with the increment of H2 Gas‐Puff rate. This paper also numerically investigates the impact of recombination processes on the detached formation. The ionization, charge–exchange, and recombination of H have been included as a particle and an energy sink and source parts of the fluid equations. The reaction rate coefficient of molecular activated recombination (MAR) has been recently introduced in the LINDA code. In this paper, we study numerically the effect of MAR on the detached plasma. The MAR plays a dominant role in making the detached plasma. The simulation clarified that H neutral particles injection can effectively generate the detached plasma by enhancing the plasma‐neutral collisions processes.

Supernova Constraints on Dark Flavored Sectors

Proto-neutron stars forming a few seconds after core-collapse supernovae are hot and dense environments where hyperons can be efficiently produced by weak processes. By making use of various state-of-the-art supernova simulations combined with the proper extensions of the equations of state including Λ hyperons, we calculate the cooling of the star induced by the emission of dark particles X0 through the decay Λ → nX 0. Comparing this novel energy-loss process to the neutrino cooling of SN 1987A allows us to set a stringent upper limit on the branching fraction, BR(Λ → nX 0) ≤ 8 × 10−9, that we apply to massless dark photons and axions with flavor-violating couplings to quarks. We find that the new supernova bound can be orders of magnitude stronger than other limits in dark-sector models.

Law of physics 20th century scientists overlooked. VI. Cosmic-scale conservation of energy

The explanation of energy conservation on the cosmic scale requires an understanding of two sets of processes. (1) The set of processes by which electromagnetic energy, the energy of photons in the free state or in the confined state, is gained or is diminished. (2) The set of processes by which the vacuum, i.e., aether, is generated or is lost—processes by which it emerges/expands and by which it suffers contraction and vanishment. At the heart of the explanation is a straightforward definition of energy at the fundamental level: Any process in which there is a quantitative change in the units of aether (the discretized medium that permeates all space) constitutes, in and of itself, a manifestation of energy. The workings of the long-overlooked mechanism are revealed. Cosmic-scale energy conservation is maintained by balancing the relevant processes of two distinct realms—the physical and the subphysical. The physical realm achieves balance by means of a harmony between processes of photon energy gain and energy loss. The subphysical realm achieves balance through the harmony between aether emergence and aether consumption/vanishment. Needless to say, the implications for cosmology are profound.

Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals

Despite considerable advances in synthesizing high-quality core/shell upconversion (UC) nanocrystals (NC; UCNC) and UCNC photophysics, the application of near-infrared (NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence (UCL) of UCNC of small size or thin protecting shell. To obtain deeper insights into energy transfer and surface quenching processes involving Yb3+ and Er3+ ions, we examined energy loss processes in differently sized solid core NaYF4 nanocrystals doped with either Yb3+ (YbNC; 20% Yb3+) or Er3+ (ErNC; 2% Er3+) and co-doped with Yb3+ and Er3+ (YbErNC; 20% Yb3+ and 2% Er3+) without a surface protection shell and coated with a thin and a thick NaYF4 shell in comparison to single and co-doped bulk materials. Luminescence studies at 375 nm excitation demonstrate back-energy transfer (BET) from the 4G11/2 state of Er3+ to the 2F5/2 state of Yb3+, through which the red Er3+4F9/2 state is efficiently populated. Excitation power density (P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and three-photonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+ emission. The intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC core. We provide a three-dimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC.

Simultaneously measuring carbon uptake capacity and chlorophyll a fluorescence dynamics in algae

Measurements of cellular carbon assimilation and chlorophyll a fluorescence are key tools for assessing the physiological capacity of algae and cyanobacteria. The uptake of CO2 from the immediate environment informs a researcher about photosynthetic rates. Chlorophyll a fluorescence dynamics can be used to infer efficiencies about light energy harvesting efficiencies and loss processes such as the loss of energy as heat through non-photochemical quenching. Here we report the utilization of novel instrument that continuously measures CO2 exchange from an aqueous solution to suspended cells synchronously with chlorophyll fluorescence. We apply the instrument to investigate the response of photosynthesis to increasing light in 3 different productive strains of eukaryotic microalgae. We found that the carbon assimilation rates of Scenedesmus obliquus (UTEX393) did not saturate, even in light fluxes approximating full sunlight. Monoraphidium sp. (26BAM) had a high nonphotochemical quenching capacity in excess light. Both of these strains, and a third, Scendesmus actus (LRBOY07), demonstrated remarkably linear relationships between carbon assimilation rates and relative electron transport estimates at lower light intensities. This work shows the utility of novel instrumentation to quickly assay the photosynthetic capabilities of microalgal strains.