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Solar and wind electricity generation technologies have become cost competitive and account for a growing share of global investment in new electricity generation capacity. Both India and Indonesia have ambitious targets for adoption of these technologies, and India has an impressive current rate of uptake. Substantial obstacles exist, however, including the entrenched positions of coal and other fossil fuels, regulatory barriers to market access, and weak abilities of electricity utilities to manage intermittent renewables. This paper reviews these obstacles and discusses strategies to overcome them. We focus on the use of reverse auction processes able to deliver low-price solar and wind contracts, as are being successfully employed in India, on tax and subsidy reform options, on regulatory and incentive-design strategies, on approaches to bolster grid management capacities, and on the importance of minimizing protectionist barriers. Our analysis covers both small-scale and large-scale systems.

The denominator of the capital adequacy ratio (CAR) for Islamic banks includes an adjustment factor, alpha, arising from the subsidisation of investment account holders’ returns using bank equity. The methodology established by the risk management standard-setting body for Islamic banks, the IFSB, estimates an alpha for each country using panel-data and normally distributed asset returns for its credit institutions. Consequently, the IFSB methodology precludes bank-specific alphas linked to the actual risk profile of underlying assets. There is also no discernible mapping between alpha and a bank’s own propensity to subsidise cash returns. This paper instead develops a new theoretical model for bank-specific alpha that is estimated for 43 Islamic banks in 11 countries. Our alpha values broadly correspond with those of the IFSB. However, a form of regulatory arbitrage is shown to exist which favors banks with relatively high alphas. This finding also has policy implications for bank efficiency and systemic risk.

We perform laser absorption spectroscopy with ultracold $^{4}\mathrm{He}$ atoms to measure the energy intervals between the $2^{3}P_{2}$ level and five levels in the $n=5$ manifold. The laser light perturbs the cold atomic cloud during the production of Bose-Einstein condensates and decreases the phase space density, causing a measurable decrease in the number of atoms in the final condensate. We improve on the precision of previous measurements by at least an order of magnitude, and report an observation of the spin-forbidden $2^{3}P_{2}\text{\ensuremath{-}}5^{1}D_{2}$ transition in helium. Theoretical transition energies agree with the observed values within our experimental uncertainty.

We present the detection of the highly forbidden 2^{3}S_{1}→3^{3}S_{1} atomic transition in helium, the weakest transition observed in any neutral atom. Our measurements of the transition frequency, upper state lifetime, and transition strength agree well with published theoretical values and can lead to tests of both QED contributions and different QED frameworks. To measure such a weak transition, we develop two methods using ultracold metastable (2^{3}S_{1}) helium atoms: low background direct detection of excited then decayed atoms for sensitive measurement of the transition frequency and lifetime, and a pulsed atom laser heating measurement for determining the transition strength. These methods could possibly be applied to other atoms, providing new tools in the search for ultraweak transitions and precision metrology.

Comparison of high-accuracy calculations with precision measurement of the 413-nm tune-out wavelength of the $\mathrm{He}(2{\phantom{\rule{0.16em}{0ex}}}^{3}{S}_{1})$ state provides a unique test of quantum electrodynamics (QED). We perform large-scale relativistic-configuration-interaction (RCI) calculations of the tune-out wavelength that include the mass-shift operator and fully account for leading relativistic nuclear recoil terms in the Dirac-Coulomb-Breit (DCB) Hamiltonian. We obtain the QED correction to the tune-out wavelength using perturbation theory, and the effect of finite nuclear size is also evaluated. The resulting tune-out wavelengths for the $2{\phantom{\rule{0.16em}{0ex}}}^{3}{S}_{1}({M}_{J}=0)$ and $2{\phantom{\rule{0.16em}{0ex}}}^{3}{S}_{1}({M}_{J}=\ifmmode\pm\else\textpm\fi{}1)$ states are 413.084 26(4) nm and 413.090 15(4) nm, respectively. When we incorporate the retardation correction of 0.000 560 0236 nm obtained by Drake et al. [Hyperfine Interact 240, 31 (2019)] to compare results with the only current experimental value of $413.0938({9}_{\text{stat}})({20}_{\text{syst}})$ nm for the $2{\phantom{\rule{0.16em}{0ex}}}^{3}{S}_{1}({M}_{J}=\ifmmode\pm\else\textpm\fi{}1)$ state, there is $1.4\ensuremath{\sigma}$ discrepancy between theory and experiment, which stimulates further theoretical and higher precision experimental investigations on the 413-nm tune-out wavelength. In addition, we also determine the QED correction for the static dipole polarizability of the $\mathrm{He}(2{\phantom{\rule{0.16em}{0ex}}}^{3}{S}_{1})$ state to be 22.5 ppm, which may enable a new test of QED in the future.

The problem of calculating the tune-out wavelength for an atom interacting with a plane electromagnetic wave is formulated as a zero in the Rayleigh scattering cross section, rather than a zero in the dynamic polarizability. Retardation (finite wavelength) corrections are discussed in the velocity gauge, and possible gauge transformations to a length form are investigated. For the special case of S-states, it is shown that a pure length form exists for the leading pxz retardation correction, even though one does not exist in general. The results of high-precision calculations in Hylleraas coordinates are presented for the tune-out wavelength of helium near the 23S − 33P transition at 413 nm.

Hydrogen as a fuel is clean burning, but production can cause substantial greenhouse emissions. Some buyers will prefer to pay a higher price to ensure purchase of low-embedded emissions hydrogen, but it is impossible to determine embedded emissions by examining the end product. Certification of embedded emissions will thus play a key role in the future of hydrogen as a low-emission energy carrier. The boundaries of the supply-chain elements covered in the emissions accounting of certification schemes will have substantial implications for emission-reduction incentives and international tradability. We review the boundary definitions of existing and emerging hydrogen certification schemes. Further, we provide an evidence-based assessment of the magnitude of emissions likely to occur within each boundary of the supply chain. We find varying approaches to boundary definitions in the surveyed schemes. The exclusion of feedstock or transport elements risks ignoring major fractions of supply-chain emissions. In order to balance tradability and emissions-reduction incentives, we recommend that hydrogen certification schemes be designed to follow a modular approach. This type of modular approach would place those with decision-making power over the relevant piece of the supply chain in the position of certifying the emissions within that supply-chain boundary.

This study evaluates the impact of profit-sharing investment accounts (PSIAs) on shareholders’ wealth. Using probabilistic tools, we derive an explicit formula for PSIA value. We apply this formula to calculate account values for a sample of 52 banks in 13 countries and determine an empirical rank order of value-drivers. We also assess the impact of returns’ smoothing schemes on shareholders’ wealth, namely the use of reserves and/or subsidies to adjust cash returns to investment account holders. We find that the value of PSIAs varies widely amongst banks, and that originating high-quality assets dominates returns’ smoothing in the value creation process. We also find that if subsidies are used without reserves to smooth returns, then shareholders’ wealth is destroyed in the long term for 77% of banks in our sample. This finding supports the practice of prioritising reserves over subsidies to smooth returns.

1. End-to-end electricity market design: lessons from the Australian National Electricity Market The Future Electricity Market Summit was held over three days (18–20 November, 2019) and comprised plenary sessions on the key themes, followed by breakout discussion sessions. The eight papers in this Special Issue reflect both the presentations and the discussions of these themes, and are aimed at identifying the key issues that will need to be addressed in the design of Future Electricity Markets in a decarbonised economy. The chapter abstracts contained in this overview provide a flavour for the thematic areas discussed.

The shift to widely distributed forms of energy generation and storage, requiring increased interconnectivity to geographically balance supply with distributed demand for electricity, creates a more complex electrical network – the ‘Internet of Energy’. A growing array of threats now impact the resilience of the electrical network including digitalisation, cybersecurity, technological changes of the power system, and the potential for climate change to expose the system to more extreme weather events. Whether distributed and renewable electricity systems will be more resilient through multiple pathways and redundancy, or less resilient due to greater cybersecurity risks than a conventional centralised electricity system, is the key focus of this paper.

Two-photon absorption is employed to record sub-Doppler molecular-beam spectra of oxygen (16O2), excited to the υ' = 1 level of its (X 2Πg) 5dπ 1 Σ g + Rydberg state above 95 130 cm–1 and detected by photoionisation in a time-of-flight instrument. A nonlinear-optical source generates single-longitudinal-mode pulses of coherent ultraviolet light at ∼210 nm with sufficiently narrow optical bandwidth to enable more detailed lineshape measurements of rovibronic features than had been achieved in an early investigation [Pratt et al., J. Chem. Phys. 1990; 93: 3072–84]. A spectral width of 0.59 ± 0.02 cm–1 is derived by Lorentzian and Beutler-Fano lineshape fits to the prominent PQ13(0) feature, nominally at ∼95 133.7 cm–1 in that spectrum; our estimated width is significantly narrower than the previously reported width of ∼1.0 cm–1. Likewise, the adjacent RQ11(2) feature, nominally at ∼95 143.8 cm–1, is found to be markedly broader (2.2 ± 1.5 cm–1), which is consistent with the supposed effects of J′-dependent predissociation arising from overlap between the (X 2Πg) 5dπ 1 Σ g + Rydberg manifold and other dissociative states. The dependence of the O2+ and O+ ion signals on acceleration voltages, O2-jet stagnation pressure, ultraviolet pulse energy and optical polarisation are also examined.

Islamic banks have access to only short-dated funding sources resulting in asset liability mismatches when financing assets with longer maturities. Maturity mismatches give rise to a risk that an unexpected increase in the cost of refinancing liabilities as they mature will not be offset by corresponding asset returns. Exposure to refinancing risk is exacerbated by paying returns to providers of off balance sheet funds which do not covary with the returns of corresponding assets as they would from a stricter application of sharia principles underlying these funding structures. The active hedging of refinancing risk by Islamic banks is also challenged due to a lack of suitable hedging instruments as well as differing sharia opinions concerning their permissibility. As an alternative to risk transference through hedging, this paper develops a framework to quantify a reserve to instead absorb refinancing risk which is distinguished from reserves already in use by Islamic banks, namely the investment risk and profit equalization reserves.

A tunable, narrowband laser system, developed for high-resolution ultraviolet spectroscopy of atoms and molecules and previously applied to two-photon excitation of rare-gas atoms, now offers prospects for new measurements of atmospheric molecules such as oxygen.

A two-dimensional mathematical model was developed to predict the dynamic response of a moored, floating platform mounting a tidal turbine in current and waves. The model calculates heave, pitch, and surge response to collinear waves and current. Waves may be single frequency or a random sea with a specified spectrum. The mooring consists of a fixed anchor, heavy chain (forming a catenary), a lightweight elastic line, and a mooring ball tethered to the platform. The equations of motion and mooring equations are solved using a marching solution approach implemented using MATLAB. The model was applied to a 10.7-m twin-hulled platform used to deploy a 0.86-m shrouded, in-line horizontal axis turbine. Added mass and damping coefficients were obtained empirically using a 1/9 scale physical model in tank experiments. Full-scale tests were used to specify drag coefficients for the turbine and platform. The computer model was then used to calculate full-scale mooring loads, turbine forces, and platform motion in preparation for a full-scale test of the tidal turbine in Muskeget Channel, Massachusetts, which runs north-south between Martha’s Vineyard and Nantucket Island. During the field experiments, wave, current, and platform motion were recorded. The field measurements were used to compute response amplitude operators (RAOs), essentially normalized amplitudes or frequency responses for heave, pitch, and surge. The measured RAOs were compared with those calculated using the model. The very good agreement indicates that the model can serve as a useful design tool for larger test and commercial platforms.

Ghost imaging with correlated photon pairs has been applied to remote sensing without the spatially detected photons interacting with the object: here we demonstrate for the first time ghost imaging using correlated atom pairs.

We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference.

A chirp-minimized, nanosecond-pulsed system has been developed to generate tunable coherent ultraviolet light at ∼212.5 nm by fourth-harmonic conversion of output from an amplified, injection-seeded optical parametric oscillator (OPO). Our CHAPS (coherent heterodyne-assisted pulsed spectroscopy) method is used to characterize the frequency stability and optical bandwidth of the system’s output radiation by recording sub-Doppler two-photon excitation spectra of krypton. In our new scanned-reference variant of CHAPS, the central frequency for each amplified OPO pulse is logged by the optical-heterodyne chirp-analysis software, with the frequency of the seed laser slowly tuned and monitored by a high-resolution wavemeter, unlike our previous implementation of CHAPS where the seed-laser frequency was fixed. For the amplified, up-converted pulses at ∼212.5 nm, our CHAPS measurements indicate an optical bandwidth of ∼100 MHz, consistent with the Fourier-transform limit of their duration (∼4.5 ns).

Very-long-baseline interferometry (VLBI) for high-resolution astronomical imaging requires phase-stable frequency references at widely separated radio-telescope antennas. For the first time to our knowledge, we have disseminated a suitable radio-frequency (RF) reference for VLBI over a “real-world” telecom optical-fiber link between radio telescopes that are >100 km apart, by means of an innovative phase-conjugation technique. Bidirectional optical amplification is used in parallel with live traffic, and phase perturbations in the effective optical-fiber path length are compensated. This RF-over-fiber approach obviates the need for separate hydrogen masers at each antenna, offering significant advantages for radio-astronomy facilities such as the Square Kilometer Array.

International audience; Powerful ultrafast laser pulses have a unique capability to ablate material from the surface without heat propagation into the bulk due to the nonlinear nature of the laser-surface interaction. This quality offers a new application of ultrafast lasers for restoration of objects of art and heritage artefacts. We discuss the laser-based cleaning methods used in art restoration, analyse the potential advantages and challenges of using ultrafast laser pulses, and present new encouraging results on using ultrafast lasers in the field of heritage conservation.

Ghost imaging is a counter-intuitive phenomenon-first realized in quantum optics-that enables the image of a two-dimensional object (mask) to be reconstructed using the spatio-temporal properties of a beam of particles with which it never interacts. Typically, two beams of correlated photons are used: one passes through the mask to a single-pixel (bucket) detector while the spatial profile of the other is measured by a high-resolution (multi-pixel) detector. The second beam never interacts with the mask. Neither detector can reconstruct the mask independently, but temporal cross-correlation between the two beams can be used to recover a 'ghost' image. Here we report the realization of ghost imaging using massive particles instead of photons. In our experiment, the two beams are formed by correlated pairs of ultracold, metastable helium atoms, which originate from s-wave scattering of two colliding Bose-Einstein condensates. We use higher-order Kapitza-Dirac scattering to generate a large number of correlated atom pairs, enabling the creation of a clear ghost image with submillimetre resolution. Future extensions of our technique could lead to the realization of ghost interference, and enable tests of Einstein-Podolsky-Rosen entanglement and Bell's inequalities with atoms.

Optical-fiber networks, compensated for path-length fluctuations, enable long-distance dissemination of a radio-frequency signal for precise spectroscopic calibration at remote sites in environmental, industrial and energy-monitoring applications.

Passive phase-conjugation enables precise fiber-optical transfer of radio-frequency reference signals over long distances, yielding high long-term stability for radio-astronomy and remote-sensing applications without active path-length stabilization.

Rooftop solar systems have two major benefits: a reduction of carbon emissions (a public good) and future energy bill savings for consumers. However, the availability of solar energy systems to low-income households is constrained by access to finance for the initial investment cost, an issue which could potentially be addressed with the use of income contingent loans (ICLs). By applying unconditional quantile econometric methods to HILDA income data we illustrate that for a $10,000 loan for home owners ICLs can be used with little or no cost to government to help finance the next one million solar energy devices.

The use of laser technology for cleaning heritage artefacts is gaining increasing interest both in Australia and overseas. Laser cleaning is a dry and contact-free process, which selectively removes contaminating dirt or coatings (including hazardous contaminants such as radioactivity and biological material), minimises mechanical and chemical disruption of historic surfaces and generates minimal waste. However, the disadvantage of current lasers for conservation is that their relatively long pulse duration allows heat and shock waves to travel into the substrate, potentially causing damage to historic surfaces. Different laser types are also needed to treat different materials, which limits the range of materials any one laser unit can treat. The femtosecond pulses used by ultrafast lasers however, are too short to allow heat or shock waves to travel into the substrate. They ablate very thin surface layers through a process known as non-thermal or non-equilibrium laser ablation. This allows highl...

Sources of rare gas atoms in excited metastable states have been used to expose photoresist-coated substrates to demonstrate atom lithography. These thermal atomic beams are usually created by discharge sources that also produce copious amounts of UV radiation. The UV radiation simultaneously illuminates the substrate and may play a complementary role in altering the photoresist together with the metastable atoms. In the experiments reported here, we have isolated the UV component using a magnetic hexapole lens to focus a thermal beam of metastable helium atoms around a fiducial mask that blocks the UV light. This creates an atom lithography exposure that is the result of illumination by the atoms alone. We have also modelled the performance of the magnetic hexapole lens as a potentially useful device for atom lithography.

In this, the hundredth year since Einstein first postulated the existence of photons, the successful application of wave - particle duality to matter has seen an explosion of activity in the field of atom optics and Bose - Einstein condensation (BEC). This article provides a brief introduction to atom optics, illustrated with applications taken from experiments using helium atoms in long-lived (metastable) excited states. Metastable helium atoms store the greatest amount of energy (∼20 electron volts) in any atomic or molecular system. They behave like nano-hand grenades, making it easy to detect single atoms, opening up promising applications as well as fundamental studies of the quantum statistical properties of atomic systems.

A method for optimizing the design and construction of a Zeeman slower coil is presented. Unlike traditional designs, the measured magnetic field profile very accurately matches the desired field profile, enabling significant advantages for loading a magneto-optic trap.

We have developed a novel, high flux source of metastable rare gas atoms (helium, neon and argon) that uses liquid helium cooling to reduce the initial atomic velocity. Fluxes exceeding 1014 atoms/ster/s with He and Ne were obtained. With average velocities of ∼600 m/s for He and ∼300 m/s for Ne and Ar, this source will enable simpler, more compact beam lines for loading magneto-optical traps.

The work was supported by the European Community, under the Access to Research Infrastructures initiative of the Improving Human Potential Program, Contract No. HPRI-CT-1999-00064. K.G.H.B. was supported by the Scientific Visits to Europe Program of the Australian Academy of Science.

We discuss the quantum reflection of metastable 2 3 S helium atoms in (square) hollow optical fibres of fused silica, used as atomic waveguides. Under realistic experimental conditions, retardation effects in the atom-surface potential play a dominant role; they can increase the reflection probability by an order of magnitude and lead to a significant yield of quantum reflected atoms, amounting to several percent of the incident atomic flux.

High-resolution, laser-based photoabsorption cross-section measurements in the weakly absorbing windows between the (11,0) and (16,0) Schumann–Runge bands of O2 have been performed at liquid-nitrogen temperature and the results compared with corresponding coupled-channel Schrodinger-equation (CSE) and line-by-line model calculations. While the symmetric-line- shape-based line-by-line model cross sections differ significantly from experiment, the excellent agreement found between the CSE and experimental window cross sections serves to confirm clearly for the first time the CSE-model predictions of band shape asymmetry and quantum-mechanical interference effects, especially in the (11,0)–(14,0) band region.

Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort (

We show long-distance precise synchronization of a radio-frequency signal over an optical-fiber network without actively stabilizing the optical path length, yielding long-term stability comparable to a hydrogen maser for remote sensing applications.

Injection-seeded nonlinear-optical tunable pulsed light sources are described and applied to sub-Doppler two-photon excitation spectroscopy of isotope energy shifts and hyperfine structure in high-energy Rydberg levels of atomic xenon.

We present the first measurement for helium atoms of the tune-out wavelength at which the atomic polarizability vanishes. We utilise a novel, highly sensitive technique for precisely measuring the effect of variations in the trapping potential of confined metastable ($2^{3}S_{1}$) helium atoms illuminated by a perturbing laser light field. The measured tune-out wavelength of 413.0938($9_{Stat.}$)($20_{Syst.}$) nm compares well with the value predicted by a theoretical calculation (413.02(9) nm) which is sensitive to finite nuclear mass, relativistic, and quantum electro-dynamic (QED) effects. This provides motivation for more detailed theoretical investigations to test QED., Comment: 5 pages, 4 figures

Despite their importance to the photochemistry of the terrestrial atmosphere, and many experimental studies, previous characterization of the Schumann–Runge (SR) bands of O 2, [Formula: see text] (1750–2050 Å) has been limited by poor experimental resolution. In addition, our understanding of the SR spectrum is incomplete, many rovibrational transitions in the perturbed region of the spectrum [B(v > 15)] remaining unassigned. We review new very-high-resolution measurements of the O 2 photoabsorption cross section in the SR bands. Tunable, narrow-bandwidth background vacuum-ultraviolet (VUV) radiation for the measurements (~ 7 × 105 resolving power) was generated by the two-photon-resonant difference-frequency four-wave mixing in Xe of excimer-pumped dye-laser radiation. With the aid of these cross-section measurements, rovibrational and line-shape analyses have led to new insights into the molecular structure and predissociation dynamics of O 2. The current VUV laser-spectroscopic measurements are shown to compare favourably with results from two other very-high-resolution experimental techniques, namely laser-induced fluorescence spectroscopy and VUV Fourier-transform spectroscopy, the latter performed using a synchrotron source.

We present a novel design for a single-mode, hollow optical fibre, which is suitable for use as a waveguide for atomic de Broglie waves. The design, development and characterisation of such a fibre are discussed, as well as an optimised method for coupling light into the fibre.

Magneto-optic traps which employ current windings to generate pulsed magnetic fields require rapid switch-off times for many applications. Practical difficulties in attaining rapid switch-off of the magnetic field, including the generation of induced currents, are addressed. Several methods for minimizing the switch-off time are presented which do not require complex feedback mechanisms involving direct measurement of the magnetic field.

Using narrow-bandwidth vacuum-ultraviolet radiation generated by difference-frequency four-wave mixing in Xe, the O2 photoabsorption cross section in the Schumann–Runge system B 3Σu−←X 3Σg−, near the dissociation limit of the B state, is measured with a resolution of ∼0.1 cm−1 full-width at half-maximum. The rotational structure of B−X(22,0) is assigned for the first time, and evidence is found for transitions into the F1 levels of B(v=23). Experimental values for the triplet-splitting constants λ and γ for B(v=22) are found to be inconsistent with the rising trend observed for v⩽19, due to a change in the sense of the perturbation of the B-state levels by the C′ 3Πu levels near B(v=20). A new value for the dissociation energy of the B state, D(B)=57 136.2±0.3 cm−1, determined from an analysis of the observed and missing lines near the dissociation limit, is in excellent agreement with previous values arising from the observation of rotational thresholds in the Schumann–Runge continuum. © 2001 American In...

We describe a high flux source of cold (80 K) metastable helium atoms. The source employs a direct current nozzle discharge which produces in excess of 1015 atoms/steradian/s. Liquid nitrogen cooling of the discharge source yields atomic velocities below 900 ms−1. Such a source has practical applications for experiments concerned with laser cooling and trapping of metastable helium atoms.

The realisation of an atomic waveguide will be an important component for the development of future atom optic devices such as large angle atom interferometers. Hollow optical fibres that employ repulsive (blue detuned) evanescent light fields to guide the atoms are one approach to this technology. We report here on multimode guiding of metastable helium ( 2 3 S 1 ) atoms through hollow optical fibres that support multimode light fields. In order to produce efficient single-mode atom guiding, hollow fibres supporting single light mode propagation will be required to generate uniform evanescent light fields inside fibre wall. We have recently developed such a fibre and report on the suitability of its light transmission characteristics for atom waveguiding.

Observation of laser-induced continuum structure (LICS) in sodium due to the coupling of a bound state to the continuum by a strong laser field has been reported elsewhere. Such experiments have mostly employed a single laser photon to probe the structured continuum from the ground state. Other experiments have used multiphoton (third harmonic) probe schemes, but only one of these has successfully observed LICS, in agreement with theoretical predictions. We report here a very similar experiment generating third-harmonic radiation in sodium to probe the anticipated LICS produced by coupling the 5s state to the p continuum. However, under no conditions was any continuum structure observed, in agreement with in a number of other experiments, but at variance with theoretical predictions.

Atom lithography commonly employs self-assem- bled monolayers (SAMs) of alkanethiols which act as resists to protect prepared surfaces. Metastable atomic species such as helium are used to damage the resist, enabling pattern transfer via mask lithography, followed by wet chemical etching. The damage mechanism is, however, not well understood. Here we report studies of fragmentation of dodecanethiol (DDT) molecules embedded in helium nano-droplets that have been irradiated by an electron beam. The results of the charge-transfer fragmentation process provide the first experimental data on the damage mechanisms that occur in the metastable helium/SAM interaction.

An open ocean aquaculture net pen syste1n was developed for offshore deployment south of the Isles of Shoals, New Hampshire, USA in 55 meters of water. Two cages were specified for the growout of summer flounder as part of an interdisciplinary effort at the University of New Hampshire involving engineers, biologists, economists, and commercial fishermen. This effort included the design of mooring system suitable for the offshore environment. Assembly and deployment of these cages and associated moorings occurred in the summer of 1999. An overview of the procedures and techniques used during these efforts are presented here.

Results are presented of a comparative study in which three distinct high-resolution experimental techniques (vacuum-ultraviolet laser spectroscopy, laser-induced fluorescence spectroscopy and vacuum-ultraviolet Fourier-transform spectroscopy) were used to study predissociation in the Schumann-Runge bands of O2 B 3Σu−(v′)←X 3Σg−(v″) with v′=13 and 14. Our measurements are the first to be performed at high resolution for these levels and represent a significant advance on previous knowledge, characterizing completely the fine-structure and rotation dependencies of the B 3Σu−(v=13 and 14)-state predissociation for the first time. The measured fine-structurespecific linewidths will result in significant improvements in the parameterization of models describing predissociation of the B-state and will have an impact on the development of realistic photochemical models of the terrestrial atmosphere. Good agreement was found between linewidths measured using vacuum-ultraviolet laser spectroscopy and laser-induce...

We have extended two-photon Doppler-free spectroscopy to the vacuum ultraviolet spectral region, to accurately measure the He $^{1}1S\ensuremath{-}^{1}2S$ transition at 120 nm. Our result is 4 984 872 315(48) MHz. This yields a ground state Lamb shift of 41 104(48) MHz, in fair agreement with theory and other experiments. This approach has the potential for significantly better accuracy once improvements in the laser and the wavelength metrology are implemented.

Access to solar energy systems by low-income households is constrained by availability of finance. We demonstrate that income contingent loans can be used to overcome this market failure with little or no cost to government.