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Photodissociation dynamics after excitation of the A˜ state ν′2 = 4 (umbrella) level of ammonia are investigated using ultrafast time-resolved velocity map ion imaging (TR-VMI). These studies extend upon previous TR-VMI measurements[K. L. Wells, G. Perriam, and V. G. Stavros, J. Chem. Phys.130, 074308 (Year: 2009)]10.1063/1.3072763, which reported the appearance timescales for ground state NH2(X˜)+H photoproducts, born from non-adiabatic passage through an X˜/A˜ state conical intersection (CI) at elongated H–NH2 bond distances. In particular, the present work sheds new light on the formation timescales for electronically excited NH2(A˜)+H species, generated from NH3 parent molecules that avoid the CI and dissociate adiabatically. The results reveal a step-wise dynamical picture for the production of NH2(A˜)+H products, where nascent dissociative flux can become temporarily trapped/impeded around the upper cone of the CI on the A˜ state potential energy surface (PES), while on course towards the adiabatic dissociation asymptote – this behavior contrasts the concerted mechanism previously observed for non-adiabatic dissociation into H-atoms associated with ro-vibrationally “cold” NH2(X˜) . Initially, non-planar NH3 molecules (species which have the capacity to yield adiabatic photoproducts) are found to evolve out of the vertical Franck-Condon excitation region and towards the CI region of the A˜ state PES with a time-constant of 113 ± 46 fs. Subsequently, transient population encircling the CI then progresses to finally form NH2(A˜)+H photoproducts from the CI region of the A˜ state PES with a slower time-constant of 415 ± 25 fs. Non-adiabatic dissociation into ro-vibrationally “hot” NH2(X˜) radicals together with H-atoms is also evidenced to occur via a qualitatively similar process.

INTRODUCTION: Adolescents are known to have high risk factors for sleep disorders, yet the youth rates of sleep disturbances are unknown. AIM: This study aimed to determine the prevalence of sleep disorders among New Zealand high school students. METHODS: The Auckland Sleep Questionnaire (ASQ) was administered to high school students at six schools in the North Island. Schools were chosen to reflect a range of ethnicities and school deciles, which identify the socioeconomic status of households in the school catchment area. RESULTS: A total of 1388 students completed the ASQ. The median age was 17 years (range 14–23) and females represented 43.5% (n=604) of the total group. A total of 37.2% of the students surveyed reported having significant sleep symptoms lasting longer than one month. Depression and anxiety were present in 51.7% and 44.8% of students reporting a sleep problem, respectively. A moderate correlation was observed between sleep problems and depression (r=0.34, p

This chapter begins with a magician's epilogue: Now my charms are all o'erthrown, And what strength I have's mine own, Which is most faint. The words are Keith Thomas' at the beginning of the last chapter of Religion and the Decline of Magic . The appropriation involved in the text's conceit of Keith Thomas as Prospero is wittily apt: at the end of their magical works, both Thomas and Prospero contemplate the decline of magic (the title of Thomas' last chapter), both ask for release from their labours, perhaps both anticipate the cooperation and applause of their audiences with ‘the help of your good hands’. There are further consequences to this historian of magic speaking the words of a Renaissance magician from a play. For Thomas' appropriation causes his text to play at this moment between Renaissance history and Renaissance fictions, so that we glimpse not only Keith Thomas as Prospero, but also Prospero as Keith Thomas. As a result of Thomas' appropriation, we can catch sight in The Tempest , particularly in Prospero's famous renunciation of magic, as well as in this epilogue, of Prospero contemplating the prospect of magic's decline in the seventeenth century, and perhaps even the decline in that century of princely theurgy as it was exercised in what Orgel has called the ‘illusion of power’ of the Jacobean and Caroline court masque. To extend this play between history and fiction in Thomas' epigraph a little further: it is extraordinarily difficult to get at any ‘history’ of events in The Tempest in a version not mediated to us by Prospero's authority, retelling or memory.

1. Introduction: Keith Thomas and the problem of witchcraft: explanations and representations of witchcraft since Religion and the Decline of Magic Jonathan Barry Part I. The Crime and its History: 2. 'Many reasons why': Witchcraft and the problem of multiple explanation Robin Briggs 3. 'Witchcraft Studies' in Austria, Germany and Switzerland Wolfgang Behringer 4. State-building and witch-hunting in early modern Europe Brian Levack Part II. Witchcraft and Religion: 5. The Devil in the Old World and the New Fernando Cervantes 6. 'Saints or sorcerers': Quakerism, demonology and the decline of witchcraft in seventeenth-century England Peter Elmer Part III. The Making of a Witch: 7. The descendants of Circe: witches and Renaissance fictions Gareth Roberts 8. Witchcraft and fantasy in early modern Germany Lyndal Roper 9. The Devil in East Anglia: the Matthew Hopkins trials reconsidered Jim Sharpe Part IV. Witchcraft and the Social Environment: 10. Witchcraft in early modern Kent: stereotypes and the background to accusations Malcolm Gaskill 11. Patriarchal reconstuction and witch-hunting Marianne Hester Part V. Decline: 12. Witchcraft repealed Ian Bostridge 13. On the continuation of witchcraft Willem de Blecourt.

THE presenilin 1 gene has recently been identified as the locus on chromosome 14 which is responsible for a large proportion of early onset, autosomal dominantly inherited Alzheimer's disease (AD). We have elucidated the intron/exon structure of the gene and designed intronic primers to enable direct sequencing of the entire coding region (10 exons) of the presenilin gene in a large number of families. This strategy has enabled us to find a further two novel mutations in the gene. We discuss the distribution of mutations and the proportions of autosomal dominant AD with a mean age of onset below 60 years caused by mutations in this gene.

Time‐dependent wavepacket calculations have been carried out to elucidate the quantum dynamical evolution of coherent molecular states undergoing case Ic predissociation. Asymptotic product states are formed by repeated curve crossing between diabatic states and adiabatic barrier tunnelling, the relative contributions of which are delineated at different excitation energies and for different pulse widths. The roles of vibrational motion and interference between diabatically and adiabatically trapped wavepackets on the coherent state evolution are likewise determined.

The recent growth of Experimental Semiotics (ES) offers us a new option to investigate human communication. We briefly introduce ES, presenting results from three themes of research which emerged within it. Then we illustrate the contribution ES can make to the investigation of human communication systems, particularly in comparison with the other existing options. This comparison highlights how ES can provide an engine of discovery for understanding human communication. In fact, in complementing the other options, ES offers us unique opportunities to test assumptions about communicative behavior, both through the experimenters' planned manipulations and through the unexpected behaviors humans exhibit in experimental settings. We provide three examples of such opportunities, one from each of the three research themes we present.

The recent growth of Experimental Semiotics (ES) offers us a new option to investigate human communication. We briefly introduce ES, presenting results from three themes of research which emerged within it. Then we illustrate the contribution ES can make to the investigation of human communication systems, particularly in comparison with the other existing options. This comparison highlights how ES can provide an engine of discovery for understanding human communication. In fact, in complementing the other options, ES offers us unique opportunities to test assumptions about communicative behavior, both through the experimenters' planned manipulations and through the unexpected behaviors humans exhibit in experimental settings. We provide three examples of such opportunities, one from each of the three research themes we present.

Here we integrate spatial information on annual burnt area, fire frequency, fire seasonality, fire radiative power and fire size distributions to produce an integrated picture of fire regimes in southern Africa. The regional patterns are related to gradients of environmental and human controls of fire, and compared with findings from other grass-fuelled fire systems on the globe. The fire regime differs across a gradient of human land use intensity, and can be explained by the differential effect of humans on ignition frequencies and fire spread. Contrary to findings in the savannas of Australia, there is no obvious increase in fire size or fire intensity from the early to the late fire season in southern Africa, presumably because patterns of fire ignition are very different. Similarly, the importance of very large fires in driving the total annual area burnt is not obvious in southern Africa. These results point to the substantial effect that human activities can have on fire in a system with high rural population densities and active fire management. Not all aspects of a fire regime are equally impacted by people: fire-return time and fire radiative power show less response to human activities than fire size and annual burned area.

Orange luminescence attributable to a core of silicon atoms in alkyl-capped crystalline quantum dots excited at λa=355 and 405 nm is investigated as a function of applied intensity and time. The intensity of luminescence displays a linear power dependence on the intensity of the applied field, from which an exponent n=0.94±0.02 commensurate with single-photon absorption is derived. The dependence of luminescence on time is observed to be strongly nonexponential and is optimally accounted for by a probability density function which describes a continuous distribution of two decay times: the behavior is characteristic of a pair of elementary steps connected with light emission within a distribution of local environments, or a single rate process supported by two environments. Nonlinear least-squares fits to the time dependent luminescence formulated on this basis with a Gaussian, Lorentzian, or log-normal distribution of rates return most probable lifetimes T¯1=21±1 μs and T¯2=3.7±0.8 μs. The widths of the ...

A method to reconstruct full three-dimensional photofragment distributions from their two-dimensional (2D) projection onto a detection plane is presented, for processes in which the expanding Newton sphere has cylindrical symmetry around an axis parallel to the projection plane. The method is based on: (1) onion-peeling in polar coordinates [ Zhao et al., Rev. Sci. Instrum. 73, 3044 (2002) ] in which the contribution to the 2D projection from events outside the plane bisecting the Newton sphere are subtracted in polar coordinates at incrementally decreasing radii; and (2) ideas borrowed from the basis set expansion (pBASEX) method in polar coordinates [ Garcia et al., Rev. Sci. Instrum. 75, 4989 (2004) ], which we use to generate 2D projections at each incremental radius for the subtraction. Our method is as good as the pBASEX method in terms of accuracy, is devoid of centerline noise common to reconstruction methods employing Cartesian coordinates; and it is computationally cheap allowing images to be reconstructed as they are being acquired in a typical imaging experiment.

My name is Gareth, I am 51 years old, married and have two teenage sons. I work as a postman in a very beautiful rural area on the foothills of Cader Idris in North Wales.

The ac-Stark shift of the A 2Σ+n′=2←X 2∏rn″=0 two-photon Bohr resonance of nitric oxide at 409.8 nm is utilized to autocorrelate intense, ultrashort optical pulses at 400 nm. When they are temporally and spatially overlapped, two identical pulses shift the absorption into transient resonance with the applied two-photon energy. Interferometric autocorrelation traces are obtained by detection of A 2Σ+n′=2→X 2∏rn″=2 fluorescence as a function of the time delay between the two pulses: The method is background free and highly nonlinear. Experimental measurements are simulated through solutions to the time-dependent Schrodinger equation for one-dimensional motion of an electron in an electric field, which procedure yields a measure of the incident pulse width.

The collisional quenching of Sr(5 3PJ) 1.807 eV above the Sr(5 1S0) ground state, by the molecules hydrogen and deuterium, has been investigated over the temperature range 725–1100 K. Sr(5 3P1) was generated by repetitive pulsed dye-laser excitation of strontium vapour at λ= 689.3 nm [Sr(5 3P1)â†� Sr(5 1S0)] in the presence of an excess of helium buffer gas, and in a slow-flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within the Sr(5 3PJ) spin-orbit manifold, Sr(5 3P1) was monitored photoelectrically as a function of time at the resonance wavelength using ‘pre-trigger photomultiplier gating’ and boxcar integration with microcomputer interfacing for data analysis. Absolute second-order rate constants for the quenching of Sr(5 3PJ) by hydrogen and deuterium, each at sixteen temperatures within the overall range employed, yield the following Arrhenius forms (1σ errors): kH2= [graphic omitted] × 10–9 exp (–49.4 ± 1.3 kJ mol–1)/RT cm3 molecule–1 s–1 and kD2= [graphic omitted] × 10–10 exp (–50.6 ± 1.1 kJ mol–1)/RT cm3 molecule–1 s–1. The activation energies are approximately one-half the reaction endoergicities to yield SrH and SrD in their electronic and vibrational ground states and demonstrate the temperature dependence of physical energy transfer. This is in marked contrast to Mg(3 3PJ)+ H2, D2 where both chemical reaction and physical quenching have been considered to make contributions to overall removal on the assumed basis of a temperature-independent physical quenching rate. It is also in contrast to our recent results for quenching of Ca(4 3PJ) by hydrogen and deuterium, where chemical reaction was the dominant mode of removal. The temperature dependence of the diffusion coefficient, D[Sr(5 3PJ)-He], of the form αTn has yielded n= 1.54 ± 0.05, in accord with the simple expectation on the basis of the kinetic theory of perfect gases. A redetermination of the mean radiative lifetime of Sr(5 3P1) yields τe= 19.1 ± 0.4 µs, in good agreement with previous measurements using dye-laser excitation and with theoretical predictions. Finally, a reanalysis of the previous rate data for the diffusion of Ca(4 3PJ) in helium indicates that the quenching of Ca(4 3PJ) by ground-state calcium atoms, Ca(4 1S0), is characterised by a rate constant whose upper bound is 4 × 10–14 cm3 atom–1 s–1.

The collisional removal of Ca[4s3d(1D2)] by hydrogen and deuterium has been studied in the time-resolved mode in the temperature range 750–1100 K. Ca(4 1D2) was generated by pulsed dye-laser excitation of calcium vapour at λ= 457.5 nm {Ca[4s3d(1D2)]â†� Ca[4s2(1S0)]} and monitored by time-resolved forbidden atomic emission at the resonance wavelength using boxcar integration with computer interfacing. A limited number of observations was also made in emission at λ= 657.3 nm [Ca(4 3P1)→ Ca(4 1S0)+hν] arising from the removal of Ca(4 1D2) by energy pooling and emission of radiation to the states Ca(4 3P2,1). Absolute second-order rate constants for the collisional removal of Ca(4 1D2) by hydrogen and deuterium were determined for nine separate temperatures across the overall range, yielding the following Arrhenius forms: kH2=(5.5 ±1.00.9)× 10–10 exp(–14.4 ± 1.3 kJ mol–1)//RT cm3 molecule–1 s–1 and kD2=(3.9 ± 0.4)× 10–10 exp(–22.2 ± 0.8 kJ mol–1)//RT cm3 molecule–1 s–1.These data are compared with analogous results for Ca(4 3PJ)+ H2, D2. The activation energies for the collisional removal of both optically metastable states with both isotopic reactants are consistent with chemical removal to yield the diatomic hydrides CaH(D)(X2Σ+, ν″= 0). The Arrhenius pre-exponential factors (A) also support chemical removal in all cases, as seen from symmetry arguments based upon the weak spin–orbit coupling approximation. A factors for Ca(43PJ)+ H2, D2 of the order of the collision number are in accord with direct correlation between Ca(43PJ)+ H2, D2 and CaH(D)(X2Σ+)+ H(D); A factors for Ca(4 1D2)+ H2, D2 significantly lower than those are in support of the absence of such adiabatic correlations.

The kinetic study of Mg(3 1P1) and Mg(4 3S1), 4.346 and 5.108 eV above the 3 1S0 ground state, has been investigated as a function of temperature and pressure of the gases He and Kr following pulsed dye-laser excitation of magnesium vapour at λ= 457.1 nm [Mg(3 3P1)â†� Mg(3 1S0)]. Mg(3 3PJ), Mg(3 1P1), and Mg(4 3S1) were monitored in the time-domain by measurements of the atomic emission at λ= 457.1 nm, λ= 285.3 nm [Mg(3 1P1)→ Mg(3 1S0)+hν], and λ(average)= 517.6 nm [Mg(4 3S1)→ Mg(3 3PJ)+hν]. Kinetic measurements on the decay of Mg(3 3PJ) in He and Kr in the range 600–1100 K yielded the temperature dependence of the diffusion coefficients, when expressed in the form D[Mg(3 3PJ)–He] and D[Mg(3 3PJ)–Kr]∝Tn, of n= 1.64 ± 0.09 and 1.65 ± 0.09, respectively. The collisional quenching of Mg(3 3PJ) by Kr has also been investigated in this temperature range, yielding the following alternative forms for the temperature-dependent rate constant: kKr=(2.9 ± 0.7)× 10–15 exp (–3.1 ± 0.5 kJ mol–1/RT) cm3 atom–1 s–1 or kKr=(6.0 ± 0.5)× 10–17T1/2+(1.1 ± 0.8)× 10–16 cm3 atom–1 s–1, the temperature-independent term lying within the error of the measurements. The mean radiative lifetime (τe) of Mg(3 3P1) has been redetermined from all the decay measurements in the range 600–1100 K, yielding the improved result τe= 2.3 ± 0.3 ms. An approximate estimate of kMg= 2 × 10–15 cm3 atom–1 s–1 is reported for the collisional removal of Mg(3 3PJ) by Mg(3 1S0). Energy pooling to yield Mg(3 1P1) has been studied in the range 800–1100 K, the first-order decay profiles for Mg(3 1P1) and Mg(3 3P1) being consistent with Mg(3 3PJ)+ Mg(3 3PJ) annihilation at all temperatures and pressures. Estimates of the ratio of the initial yields of [Mg(3 1P1)]t= 0/[Mg(3 3P1)]t= 0 determined at different temperatures are found to be sensibly consistent with thermodynamic data for the vapour pressure of atomic Mg. Energy pooling to yield Mg(4 3S1) has been investigated from detailed measurements of the decay profiles for this atomic state using the first-order kinetic approximation at ‘long decay times’ in the range 750–1100 K. This has been interpreted quantitatively in terms of a mechanism involving the low-lying states Mg2(3Πg, 3Σ+u), 2.05 and 2.19 eV above the Mg2(X1Σ+g) ground state, and produced from the three-body recombination of Mg(3 3PJ)+ Mg(3 1S0)+ He, Kr which undergoes subsequent reaction with Mg(3 3PJ) to yield Mg(4 3S1), in accord with the earlier proposal of Breckenridge and coworkers. The mechanism is established from the dependence of the decay profiles at λ(average)= 517.6 nm on the pressure of helium and krypton at all temperatures, and by comparison with those at λ= 457.1 nm. This indicates that Mg2(3Πg, 3Σ+u) can only be placed in stationary state in this type of system when T > 1000 K. The temperature dependence of the initial yields of [Mg(4 3S1)]max/[Mg(3 3P1)]t= 0 is also found to be in sensible accord with expectation based on vapour pressure data for Mg(3 1S0).

Charged with the responsibility for conserving “natural beauty”, National Parks are, theoretically, ideally placed to promote integrated conservation policies. The experience of the Parks in this regard is reviewed, and the question posed as to whether the increasing interest paid to them in the 1980's may have served to deflect attention away from losses in the amenity of our wider countryside.

We present a kinetic study of the collisional behaviour of Mg(33PJ) with CO2 and electronic energy transfer between Mg(33PJ) and MgO over the temperature range 600–1100 K. Mg(33P1) was generated by the pulsed dye-laser excitation of magnesium vapour in a slow-flow system at λ = 457.1 nm (Mg(33P1) Mg(31S0)) and monitored by time-resolved atomic emission at the resonance wavelength using pre-trigger photomultiplier gating with Boxcar integration and computer interfacing. Absolute second-order rate constants were measured for the removal of Mg(33PJ) by CO2, yielding the Arrhenius form: k1 = (2.4 ±0.50.7)·10−10 exp (−(47.6±5.8 kJ mol−1)/RT) cm3 molecule−1s−1. Chemiluminescence was monitored in the time-domain for MgO, B1Σ+ - A1∏ and B1Σ+ - X1Σ+) for a number of vibrational levels. The molecular emission profiles were shown to be quantitatively consistent with electronic energy transfer from Mg(33PJ) to MgO, (X1Σ+ - A1∏ yielding B1Σ+) yielding MgO(B1Σ+) by correlation of the atomic and molecular emission profiles. These measurements thus demonstrate the use of the B—A and B—X band systems of MgO in the time-domain as spectroscopic markers for the kinetic behaviour of Mg(33P1), an aspect of the observations considered in detail. Vibrational temperatures were also measured for MgO(B1Σ+) using emission from vibrational levels ν′ = 0 to 4, demonstrating significant vibrational excitation on electronic energy exchange between Mg(33P1) and MgO(X1Σ+).

A study is presented of the kinetic behaviour of the optically metastable states Sr(5s5p(3PJ)) and Sr(5s4d(1D2)), each separately generated by pulsed dye-laser excitation at λ = 689.3 nm (Sr(5s5p(3P1))←Sr(5s2(1S0))) and λ = 496.1 nm (Sr(5s4d(1D2))←Sr(5s2(1S0))) in the presence of helium buffer gas. Radiative and diffusional loss of both metastable states in helium, including the effect of radiation trapping for Sr(5s5p(3PJ)), have been investigated as a function of temperature and pressure by time-resolved emission measurements. We report the following radiative lifetimes: τe(Sr(3P1)) = (19.6−0.5+0.6) μs for fluorescence via the spin-forbidden transition to the ground state; and τ(Sr(1D2)) = (412−9+10) μs for radiative loss to all lower-lying states. Both values are compared with the results of previous experimental work and theoretical calculations as appropriate. When expressed in the form D12 ∝ Tn, the measured temperature dependence of the diffusion coefficients D12(Sr(3PJ)-He) and D12(Sr(1D2-He) yielded n = 1.59±0.51 and n = 1.83±0.89, respectively. Rate constants for self-quenching of Sr(3PJ) and Sr(1D2) atoms by ground-state Sr(1S0) vapour are estimated to be kSr = (2.9−6.4)×10−14 cm3 atom−1 s−1 and k′Sr = (3.4±0.9)×10−14 cm3 atom−1 s−1 respectively. Whilst an upper limit of kHe⩽(2.6±0.6)×10−15 cm3 atom−1 s−1 is determined for collisional quenching of Sr(3PJ) atoms by He, no such effect could be observed for Sr(1D2) atoms. Energy pooling processes involving Sr(5s5p(3PJ)) atoms to yield the higher-lying 5s5p(1P1), 5s4d(1D2) and 5s6s(3S1) states are also investigated in the time domain, where the mechanisms for pooling formation are established from a quantitative comparison of the time dependence of atomic emission from the energy store and pooled states. For Sr(5s4d(1D2)), fluorescence from some 22 energy-pooled atomic states is reported, mostly arising from bimolecular collisions between two Sr(1D2) atoms with subsequent emission of radiation. Approximate relative yields into all these pooled states, estimated from extrapolation of their time-dependent decay profiles coupled with appropriate corrections for Einstein coefficients and experimental sensitivity, indicate that energy pooling collisions constitute a small “bleed-off” from the store states which does not affect their time profiles. Finally, quantum yields for emission from Sr(5s5p(3PJ)) and Sr(5s4d(1D2)) atoms and branching ratios into the 3PJ levels following laser excitation of the 1D2 state are reported. These are shown to be quantitatively consistent with a mechanism based on removal of both excited states by radiative decay and diffusion, as seen by reference to previous calculated Einstein coefficients for the relevant radiative transitions. Using experimental data reported in an earlier publication, quantum yields for emission from Ca(4s4p(3PJ)) and Ca(4s3d(1D2)) atoms and the branching ratio for production of Ca(4s4p(3PJ)) following laser excitation of Ca(4s3d(1D2)) are also determined, from which a mechanism analogous to that for atomic strontium is established.

We present a kinetic study of the collisional behaviour of Ca(4 3PJ), 1.888 eV above the 4 1S0 ground state, with hydrogen and deuterium over the temperature range 850–1075 K. Ca(4 3P1) was optically excited by repetitive pulsed dye-laser excitation at λ= 657.3 nm of calcium vapour in equilibrium with the solid at elevated temperatures in a slow-flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within the 4 3PJ spin–orbit manifold, the time-resolved emission at λ= 657.3 nm [Ca(4 3P1)→ Ca(4 1S0)+hν] was monitored photoelectrically using a boxcar integrator interfaced to a microcomputer for kinetic analysis of the atomic emission data in digital form. Absolute second-order rate constants for collisional quenching of Ca(4 3PJ) were determined at ten different temperatures in the range 850–1075 K yielding the following Arrhenius forms: k[Ca(4 3PJ)+H2]/cm3 molecule–1 s–1=[graphic omitted] × 10–9 exp[(–88.3±4.2 kJ mol–1)/RT], k[Ca(4 3PJ)+D2]/cm3 molecule–1 s–1=[graphic omitted] × 10–9 exp [(–92.9±5.0 kJ mol–1)/RT] and constituting the first temperature-dependent investigation for these processes. In both cases the rate data were also fitted to a three-parameter equation of the form kQ=B+A exp (–E/RT). The term B, which may be attributed to physical quenching, was found to be negligible in magnitude compared with the temperature-dependent term. The experimental activation energies were found to be in accord with reaction endothermicities to yield CaH and CaD (X2Σ+, ν″= 0) and the pre-exponential factors with calculated collision numbers. The results are compared with analogous rate data reported by other workers on the temperature-dependence of the quenching of Mg(33PJ) by hydrogen and deuterium. Finally, an investigation of the temperature-dependence of the diffusion of Ca(4 3PJ) in helium is presented in which the diffusion coefficient D[Ca(43PJ)+ He] is found to satisfy a temperature dependence of T1.8±0.04.

We present a kinetic study of the collisional quenching of Sr[5s4d(1D2)], 2.498 eV above the 5s2(1S0) electronic ground state, by H2 and D2 across the temperature range T= 850–1100 K. Sr(1D2) was generated by the repetitive pulsed dye-laser excitation of strontium vapour at λ= 496.1 nm {Sr[5s4d(1D2)]â†� Sr[5s2(1S0)]} in the presence of excess helium buffer gas and H2 or D2 in a slow flow system, kinetically equivalent to a static system. Its exponential decay was monitored in emission at the resonance wavelength using Boxcar integration coupled with computerized analysis. Sr(1D2) was also monitored using the more intense bi-exponential atomic emission profiles for Sr[5s5p(3PJ)](1.807 eV), resulting from emission and collisional quenching of Sr(1D2), at λ= 689.3 nm {Sr[5s5p(3P1)]→Sr[5s2(1S0)]+hν}. The resulting rate data, which involve considerable experimental scatter that is considered in some detail, can be expressed in the form: kH2= 7 × 10–10 exp (–13 kJ mol–1/RT) cm3 molecule–1s–1 and kD2= 3 × 10–10 exp (–17 kJ mol–1/RT) cm3 molecule–1s–1 the data clearly indicating low energy barriers and fully in accord with energy transfer on collision, as also found hitherto for Sr(3PJ)+ H2 and D2. This is in marked contrast to previous measurements on Ca[4s4p(3PJ)] and Ca[4s3d(1D2)] by H2 and D2 where collisional removal was totally dominated by chemical reaction. Finally, branching ratios for collisional removal of Sr(1D2) into the lower-lying Sr[5s4d(3DJ)](2.260 eV) and Sr[5s5p(3PJ)] states, for which the individual contributions could not be separated, are estimated and found to lie in the range ca. 0.3–0.9 . consideration of the observed low activation energies, reaction ergicities and branching ratio estimates suggest that the collisional quenching of Sr(1D2) by H2 and D2 is dominated by (E–E, V) transfer resulting in the production of Sr(3DJ) and Sr(3PJ).

We present a kinetic study of chemiluminescence from SrO(A1Σ+ - X1Σ+) and SrO(A'1 Π - X1Σ+) following pulsed dye-laser generation of Sr(5s5p(3PJ)), 1.807 eV above the 5s2(1S0) ground state, in the presence of CO2. This required complementary investigation of the time-dependence of both the atomic emission profiles at the resonance wavelength of λ = 689.3 nm (Sr(5s5p(3P1)) Σ Sr(5s2(1S0)) + hv) and at wavelengths of various vibronic transitions within the A—X and A'— X band systems of SrO, together with the determination of the quantitative relationship between these using the appropriate time-dependent equations for atomic and molecular emission. Decay profiles for Sr(53PJ) in the presence of CO2 across the temperature range T = 675—1100 K showed clear exponential decay behaviour, yielding the absolute second order rate constant for total collisional removal of the excited atoms of k1 = (4.7 ± 2.8) Σ 10−10 exp(- 33.3 ± 9.9 kJ mol−1 /RT) cm3 molecule −1 s−1. At elevated temperatures, the Arrhenius plot for the removal of Sr(53PJ) displayed upward curvature which is shown to be sensibly consistent with the removal of this atomic state by product SrO(X1Σ+). Chemiluminescence from transitions involving Δv sequences within SrO(A1Σ+ - X1Σ+) and within the v = 0 progression of SrO(A'1Π - X1Σ+) was monitored and analysed across the temperature range 900–1100 K. These molecular chemiluminescence profiles exhibited clear bi-exponential behaviour which, when compared with the single exponential profiles for Sr(53PJ), were quantitatively shown to be consistent with the E—(E, V) transfer processes: Sr(53PJ) + SrO(X1Σ+) SrO(A1Σ+, A'1Π, v' = n) + Sr(51S0). Vibrational excitation by this mechanism was observed up to the maximum energetically allowed by the relevant E - (E, V) process. A - X and A'- X chemiluminescence was shown to provide kinetic spectroscopic markers in the time-domain for Sr(53PJ). Estimated vibrational temperatures within SrO(A'1II) indicated some measure of vibrational excitation accompanying energy transfer. The temperature variation of the SrO(A - X) and SrO(A'-X) emission intensity was demonstrated to be consistent with thermodynamic data for atomic strontium.

We present a detailed investigation of the collisional behaviour of the optically metastable calcium atoms, Ca(4s4p( 3 P J )) (1.888 eV) and Ca(4s3d( 1 D 2 )) (2.709 eV), with N 2 O. These metastable states were generated directly by pulsed dye-laser excitation at λ = 657.3 and 457.5 nm respectively, and monitored photoelectrically in the time-resolved mode by boxcar integration using the forbidden atomic emission at these resonance wavelengths. The removal of the two atomic states by N 2 O has been characterised across the temperature range 725–1100 K, yielding the Arrhenius forms: k (Ca(4 3 P J ) + N 2 O) = (3.5 +8.5 −2.5 ) × 10 −10 exp(−36.1 ± 11.6 kJ mol −1 / RT ) cm 3 molecule −1 s −1 ; k (Ca(4 1 D 2 ) + N 2 O) = (3.8 +2.9 −1.7 ) × 10 −10 exp(−17.5 ± 3.7 kJ mol −1 / RT ) cm 3 molecule −1 s −1 . At elevated temperatures, the atomic decay profiles included the effects of components due to the collisional removal of Ca(4 3 P J ) and Ca(4 1 D 2 ) by O 2 resulting from the thermal decomposition of N 2 O, which were quantified. The main objective of the present paper concerns the accompanying time-resolved study of molecular chemiluminescence from CaO, involving the monitoring of some forty transitions in different electronic and vibronic states, and characterising the time-resolved molecular emission profiles and relating them quantitatively to parameters describing the atomic emission profiles. The following groups of chemiluminescence transitions were monitored: the CaO “orange arc band” system (nine transitions); the CaO “green arc band” system (two transitions); the CaO(A′ 1 ΠX 1 Σ + , ν′ = 8–15) band system (twenty-one transitions); the CaO(A 1 Σ + X 1 Σ + , Δν = −2 to −9 (eight transitions). The combination of the time dependences of the molecular and atomic emission profiles enabled the production of the emitting molecular states to be ascribed either specifically to direct formation from chemical reaction between Ca(4 3 P J ) and Ca(4 1 D 2 ) with N 2 O or to EE transfer between these two atomic states and CaO(X 1 Σ + ). The different routes to specific product states of CaO are presented in detail and are found to be in accord with the energetic accessibility of these states and with a correlation diagram connecting the states of Ca + N 2 O and CaO + N 2 constructed on the basis of C s symmetry on collision and using the weak spin-orbit coupling approximation. For the case of EE transfer, measurement of the vibrational temperature across ν′ = 8–15 in CaO(A′ 1 Π) indicates some degree of vibrational excitation accompanying these processes. Intensity measurements corrected for photomultiplier gain, frequency and Franck-Condon factor yielded estimates of relative populations in the emitting electronic states resulting from these two general routes. Product states arising from direct reaction were found to be in accord with symmetry arguments. Finally, the variation of such corrected molecular emission intensity measurements with temperature yielded results in broad agreement with thermodynamic data.

The collisional quenching of Ca(4 3PJ) and Sr(5 3PJ) has been studied for an equilibrium system coupled by the process Ca(4 3PJ)+ Sr(5 1S0)⇌ Ca(4 1S0)+ Sr(5 3PJ) and established following pulsed dye-laser excitation of Ca(4 1S0) to Ca(4 3P1) at λ= 657.3 nm in mixtures of calcium and strontium vapour in the presence of an excess of helium buffer gas and added quenching gases. Ca(4 3P1), Sr(5 3P1) and Sr(6 3S1) were monitored by time-resolved emission at λ= 657.3, 689.3 [Sr(5 3P1)→ Sr(5 1S0)+hν) and 679.1 nm [Sr(6 3S1)→ Sr(5 3P0)+hν], respectively, using boxcar integration. The measured first-order decay coefficients for Ca(4 3PJ) and Sr(5 3PJ) under equilibrium-coupled conditions were found to be in quantitative agreement with previously measured values of absolute second-order rate constants for the quenching gases Kr, Xe, H2, D2, N2, CO, NO, N2O, CO2, NH3, CH4, CF4, C2H2, C2H4 and C6H6, obtained using the present system, employing signal averaging, on decays of Ca(4 3PJ) and Sr(5 3PJ) individually. Finally, energy pooling according to the processes Ca(4 3PJ)+ Sr(5 3PJ)→ Sr(6 3S1)+ Ca(4 1S0), Sr(5 3PJ)Sr(5 3PJ)→ Sr(6 3S1)+ Sr(5 1S0) was investigated quantitatively from measurements at λ= 679.1 nm in the time domain and in the presence of the quenching gases.

Molecular chemiluminescence from SrO is studied in the time domain following pulsed dye-laser generation of Sr(5 3 P J ) in the presence of N 2 O at elevated temperatures (675–1100 K). Time-resolved atomic fluorescence at λ=689.3 nm and SrO chemiluminescence were optically isolated with a small monochromator and recorded photoelectrically using boxcar integration. The atomic decay profiles were employed to characterize the Arrhenius parameters for overall quenching between Sr(5 3 P J ) + N 2 O described by the overall rate constant k = (4.2 ± 1.9) × 10 −10 exp (−25.8 ± 5.7 kJ mol −1 / RT ) cm 3 molecule −1 s −1 . Time profiles for SrO chemiluminescence were characterized under conditions identical in each case to those employed to record the atomic profiles. Quantitative comparison of the time dependences of the atomic and molecular emission profiles showed that the SrO “orange” and “red” arc band emitting states result from direct reaction between Sr (5 3 P J ) + N 2 O giving rise to simple exponenti decay of chemiluminescence. By contrast SrO(A′ 1 Π) and SrO(A 1 Σ + ) result from energy transfer between Sr(5 3 P J ) and SrO (X 1 Σ + and display a bi-exponential time dependence. Estimates of vibrational temperatures within SrO (A′ 1 Π) show some measure of vibrational excitation above the Boltzmann temperature for ambient conditions, and the temperature variation of the SrO chemiluminescence intensity overall is shown to be consistent with thermodynamic data for atomic strontium.

The non-empirical SCF-LCAO-π-electron method previously developed for closed-shell molecules is extended to treat open-shell hydrocarbon systems. It is shown that the use of the Roothaan formalism, with configuration interaction involving all singly excited states, leads to a satisfactory description of the doublet state excitation energies and of the spin density distributions. Comparison of the total π-electronic energies with values relating to the corresponding closed-shell systems yields ionisation potentials in good agreement with experimental data.

In recent years, there has been considerable interest in media which exhibit significant non-linear physical properties. The non-linear optical response of many materials has attracted a great deal of attention from the telecommunications industry owing to their possible use for signal processing applications. Also, applications such as thermal imaging depend ultimately upon the proficient operation of the active material within the device structure. Traditionally, inorganic materials such as lithium niobate and strontium barium niobate have been used for non-linear optics and infra-red detection. However, the last decade or so has exposed the potentially high efficiency offered by organic materials which, coupled to the ability to engineer their physical properties by subtle modifications at the molecular level, suggests an exciting and productive future. In order to maintain compatibility with existing integrated optics and display technologies, it is often useful to process the active compound in thin film form. The stringent symmetry requirements imposed upon the molecules and their organisation in the macroscopic structure necessitates the existence of non-centrosymmetric molecular structures for second-order non-linear applications such as those mentioned above. The Langmuirandndash;Blodgett deposition technique enables such assemblies to be constructed by the sequential transfer of organic monomolecular layers from a liquid-air interface onto a solid substrate. The precise control of film thickness and molecular architecture afforded by the technique allow polar multilayer structures to be produced which possess the properties required for highly efficient second-order non-linear physical operation. This thesis describes the development of a series of novel organo-metallic complexes which possess the necessary molecular properties for LB deposition in addition to those required for the observation of a large non-linear response. The complexes offer substantially improved thermal stability over other LB materials, and are thus appealing to the industrial device engineer. Their physical properties have been systematically studied and related to their detailed molecular structure. In particular, optical second-harmonic generation studies have shown that they possess high molecular coefficients and have provided a launching stage for further development. Their high pyroelectric response has attracted much enthusiasm from both industry and academia because of their potential commercial exploitation in thermal imaging devices.

An analysis of one year of METEOSAT Spinning Enhanced Visible and Infrared Imager (SEVIRI) active fire data is presented. Fire Radiative Power (FRP) observations, acquired at a 15-minute time interval and 3 km spatial resolution, are used to estimate the total amount of African biomass combustion. African biomass combustion between February 2004 and January 2005 is estimated to be at least 855 million tonnes. FRP-derived biomass combustion estimates at a 1-degree spatial scale are found to be less than 2 kg/m2. In savanna grasslands the FRP-derived median fuel consumption estimate of 300 g/m2 is in good agreement with literature values. Analysis of fire pixel temporal persistence indicates that the majority of African fires are detected only once in consecutive 15 minute images. Fire pixel duration is longest during the peak biomass burning season with a greater proportion of pixels detected only once during the wet season. An investigation of the variability of the diurnal fire cycle is carried out with respect to land cover type, and whilst differences are noted between land covers, the diurnal characteristics for a given land cover type are similar in both African hemispheres.

The MODIS BRDF and albedo science data product (MOD43B) has been providing provisional quality products to the science community since October 2000. The operational algorithm relies on multi-date MODIS observations and a semi-empirical kernel-based bidirectional reflectance distribution function (BRDF) model to provide global one kilometer measures of BRDF, albedo (spectral and broadband) and nadir BRDF-adjusted reflectance (NBAR).

Earth observation data can provide valuable assessments for monitoring the spatial extent of (un)sustainable urban growth of the world’s cities to better inform planning policy in reducing associated economic, social and environmental costs. Western Australia has witnessed rapid economic expansion since the turn of the century founded upon extensive natural resource extraction. Thus, Perth, the state capital of Western Australia, has encountered significant population and urban growth in response to the booming state economy. However, the recent economic slowdown resulted in the largest decrease in natural resource values that Western Australia has ever experienced. Here, we present multi-temporal urban expansion statistics from 1990 to 2015 for Perth, derived from Landsat imagery. Current urban estimates used for future development plans and progress monitoring of infill and density targets are based upon aggregated census data and metrics unrepresentative of actual land cover change, underestimating overall urban area. Earth observation provides a temporally consistent methodology, identifying areal urban area at higher spatial and temporal resolution than current estimates. Our results indicate that the spatial extent of the Perth Metropolitan Region has increased 45% between 1990 and 2015, over 320 km2. We highlight the applicability of earth observation data in accurately quantifying urban area for sustainable targeted planning practices.

Annual sequences of the first reprocessed albedo, bidirectional reflectance distribution function (BRDF), and nadir BRDF-adjusted surface reflectance (NBAR) products are being evaluated. BRDF model parameters (or weights) are used to compute black sky albedo at local solar noon and white sky albedo and to compute surface reflectance at a common nadir geometry. In addition to these standard resolution albedo, BRDF, and NBAR products, which are provided in the integerized sinusoidal grid projection, the BRDF parameters, black sky albedos (at local solar noon), and white sky albedos are now also being operationally produced in a global geographic projection known as the Climate Modeling Grid (CMG). These are currently available at a 0.25 degree spatial resolution, although there is community interest in a 0.05 degree resolution. In addition to the operational CMGs, coarser 0.5 degree and 1 degree resolution versions of the reprocessed albedo data have also been produced for the ISLSCP-II initiative. The global distribution of these albedos (as they vary throughout the year) are presented, as well as discussions of the most recent evaluations of the quality of the standard products.