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Radiation damage of natural and synthetic zircon grains is evaluated by Raman spectroscopy to understand annealing and stability of fission tracks. Analyses focus on a suite of 338 Paleozoic detrital zircon grains from metamorphosed strata in the Hellenic forearc that were variably annealed by a Miocene thermal event, as well as a suite of 97 synthetic zircon grains. The Raman wavenumber shift Of V3 [SiO4] reveals that radiation damage and damage distribution in this suite mainly depends on uranium concentration. In zircon with similar uranium concentration, the Raman wavenumber shift allows for the determination of radiation damage in different crystals, which is a function of effective accumulation time. Nine detrital zircons grains with moderate radiation damage were stepwise annealed at 1000 and 1400[degrees]C, which resulted in progressive removal of radiation damage revealed in an increase of [v.sub.3] [Si[O.sub.4]] peak positions. For a partly reset sample that was brought to temperatures of ~350[degrees]C in a geologic setting (Hellenic forearc), we use the Raman measurements and uranium determination to estimate a Zircon Damage Discrimination Factor ([Z.sub.RDD]), which is our attempt to estimate only radiation damage in single grains by accounting for affects of the uranium atom in the Raman wavenumber. This discrimination allows for a separation of zircon fission track (ZFT) ages of single ages based on grains that have a low track retention (high damage, fully reset grain), thus refining the age determination of cooling in a rock that shows variable resetting. Keywords: Geochronology, zircon fission track, radiation damage, uranium content, Raman spectroscopy DOI: 10.2138/am.2010.3264

Exposure of eukaryotic cells to UV light induces a checkpoint response that delays cell-cycle progression after cells enter S phase. It has been hypothesized that this checkpoint response provides time for repair by signaling the presence of structures generated when the replication fork encounters UV-induced DNA damage. To gain insight into the nature of the signaling structures, we used time-lapse microscopy to determine the effects of deficiencies in translesion DNA polymerases on the checkpoint response of the fission yeast Schizosaccharomyces pombe. We found that disruption of the genes encoding translesion DNA polymerases Poh[kappa] and Pol[eta] significantly prolonged the checkpoint response, indicating that the substrates of these enzymes are signals for checkpoint activation. Surprisingly, we found no evidence that the translesion polymerases Rev1 and Pol[zeta] repair structures that are recognized by the checkpoint despite their role in maintaining viability after UV irradiation. Quantitative flow cytometry revealed that cells lacking translesion polymerases replicate UV-damaged DNA at the same rate at WT cells, indicating that the enhanced checkpoint response of cells lacking Pol[kappa] and Pol[eta] is not the result of stalled replication forks. These observations support a model in which postreplication DNA gaps with unrepaired UV lesions in the template strand act both as substrates for translesion polymerases and as signals for checkpoint activation. DNA damage checkpoint | Pol[eta] | Pol[kappa] | Pol[zeta] | Rev1 doi/ 10.1073/pnas.1003449107

A variety of air pollution control strategies have been investigated to reduce mercury emissions from coal-fired sources. The most developed and deployed technologies are based on adsorption of mercury onto powdered activated carbon followed by carbon collection. Mercury oxidation over selective catalytic reduction catalysts followed by wet scrubbing is another potential technique, and tests suggest that emissions reductions of 20-80% are possible, but test results are variable and ultrahigh removal (95%+) is unusual. The objective of this study was to investigate the effectiveness of electron beam irradiation to oxidize mercury vapor, to improve mercury removal with wet scrubbers or wet electrostatic precipitators (ESPs). Metallic mercury vapor samples in air and other atmospheres were prepared at concentrations of approximately 16 [micro]g/[m.sup.3]. Samples were electron irradiated at energy levels of 2.5-10 kGy, equivalent to 3.1-12.4 kJ/[m.sup.3] stack gas. Results show that mercury oxidation rate was dependent on both the gaseous atmosphere composition and the irradiation energy level. At medium energy levels, approximately 98% of gaseous mercury vapor was readily oxidized. Electron beam irradiation demonstrated high levels of mercury oxidation at the bench scale, and the technology might help improve mercury removal in wet scrubbers or wet ESPs when employed as a primary or secondary mercury oxidation technique. DOI: 10.1061/(ASCE)EE.1943-7870.0000188 CE Database subject headings: Mercury; Coal; Combustion; Oxidation; Emissions; Air pollution. Author keywords: Mercury; Coal combustion; Electron beam radiation.

The shield or shadow effect of large particles on bacteria undergoing irradiation from ultraviolet light in effluent of treated wastewater would greatly reduce the effectiveness of ultraviolet disinfection. The objective of this work is to evaluate the newly proposed method of applying a high pressure water jet (HPWJ) as a pretreatment step in combination with ultraviolet irradiation to improve the disinfection efficiency of wastewater by breaking up the large particles (reducing the shield or shadow effects). Pretreatment experiments with two HPWJ units having different water pressure output (6.9 and 13.1 MPa) and nozzles were conducted in the study on primary clarifier overflow (PCO). The experiment results revealed that the particle size distributions (PSDs) in the test samples were apparently shifted toward the small size range and the total number of particles has been greatly increased after undergoing treatment with the HPWJ. In general it is assumed that bioparticles larger than a certain size (10 [micro]m) are difficult to disinfect by ultraviolet. After the HPWJ treatment the relevant particle size range > 12.5 [micro]m in the test samples of the PCO was reduced on average by half for tested HPWJ settings. Also, a primary comparison showed that under a similar amount of energy consumption, the HPWJ performed better than the ultrasonic method did in terms of effectively breaking up large particles. As expected, the changes of PSD notably affect the efficiency of ultraviolet disinfection as tested with the collimated beam. The E. co/i and total coliform tests showed that pretreated PCO by the HPWJ enhanced the efficiency of ultraviolet disinfection by more than 1 log unit compared to treatment by ultraviolet alone when the ultraviolet dose was in the 20-30 mJ/[cm.sup.2] range. Multiple pretreatment with the HPWJ was also tested, which showed the advantage of breaking up slightly more particles, but with less enhancement of ultraviolet disinfection compared to a single pretreatment. This could possibly be due to the reduced ultraviolet transmission in the test sample caused by the presence of a larger number of suspended particles. The E. coli test results indicated that the well known 'tailing region' of typical patterns of the ultraviolet dose-response curve was eliminated or decreased after the PCO was treated by HPWJ. The application of a HPWJ step might also be beneficial in terms of cost-effectiveness. With HPWJ pretreatment it only takes about one-third of the ultraviolet light exposure time to achieve the same disinfection results as ultraviolet treatment alone in the collimated beam test. The experimental results in this study showed some degree of variation for similar experiments. This is not unusual for this kind of study, due to many uncontrolled factors such as characteristics of tested PCO samples, random error in the microbiology tests and so on. However, these experiments clearly showed that the proposal of using the HPWJ to pre-treat wastewater could be a very attractive alternative to enhance ultraviolet disinfection efficiency. DOI: 10.1061/(ASCE)EE.1943-7870.0000076 CE Database subject headings: Disinfection; Particles; Water jets; Viruses; Wastewater management.

Cathodoluminescence (CL) spectra of tridymite and cristobalite have broad peaks around 430 and 400 nm, respectively, both of which can be assigned to the [[Al[O.sub.4]/[M.sup.+]].sup.0] defect. The CL intensities of these spectral peaks in the blue region decrease with prolonged exposure to electron irradiation, similar to the short-lived luminescence observed in quartz, although quartz shows a lower decrease in CL intensity compared to these minerals. Cristobalite has a higher CL intensity reduction rate during irradiation than does tridymite. Irradiation of these minerals at low temperatures results in a more rapid decay of CL emission, whereas that of quartz shows no apparent change in the rate of CL emission at similar temperatures. Confocal micro-Raman spectroscopy of the electron irradiated surface of these minerals reveals the amorphization caused by the interaction of the electron beam with the surface layer to a depth of several micrometers. This suggests that such structural destruction diminishes the activity of CL emission centers related to the [[Al[O.sub.4]/[M.sup.+]].sup.0] defects by migration of monovalent cations associated with exchanged Al in the tetrahedral sites. Both samples present a considerable reduction of their CL intensities at higher temperature, suggesting a temperature quenching phenomenon. The activation energy in the quenching process was evaluated by a least-squares fitting of the Arrhenius plots, assuming the Mott-Seitz model. The result implies that the energy of non-radiative transition in this process might be transferred to lattice vibrations as phonons in two different manners. This might be related to different irradiation responses of the CL with a change in sample temperature. Keywords: Tridymite, cristobalite, cathodoluminescence, electron irradiation, temperature quenching, Raman spectroscopy

Colorless natural quartz can develop many extrinsic colors after exposure to ionizing radiation and heat due to trace elements such as aluminum, iron, hydrogen, lithium, and sodium. The infrared spectrum of colorless natural quartz is correlated to the development of these colors, because the bands between 3200 and 3600 [cm.sup.-1] are related to the presence of trace elements. The colors produced by [gamma]-ray or electron beam irradiation are caused by displacements of electrons in the quartz lattice and can be bleached by ultraviolet irradiation. Colors produced by irradiation and additional heating, however, are resistant to ultraviolet rays, probably due to [Li.sup.+] diffusion. The infrared spectra of colorless natural quartz crystals can be used to identify the crystals' potential for color development by irradiation and heating. At room temperature, all natural colorless samples of alpha quartz show bands at 2499, 2600, 2677, 2771, 2935, and 3063 [cm.sup.-1]. The samples that do not develop color after irradiation also show bands at 3202 and 3304 [cm.sup.-1]. The samples that become grayish to black after irradiation show three additional bands at 338 l, 3433, and 3483 [cm.sup.-1]. This last band is related to the development of the colors greenish yellow, yellow, or brown (citrine) after irradiation and heating. The samples that become grayish olive green after irradiation and olive green after additional heating show a pair of bands at 3404 and 3510 [cm.sup.-1] in addition to the former bands noted. The samples that become violet (amethyst) or green (prasiolite) after irradiation, or sky blue after irradiation plus heating show a broad band at ~3441 [cm.sup.-1] and a band at 3585 [cm.sup.-1] . Keywords: Infrared spectrometry, quartz, color, irradiation, heating

Polymer insulating materials installed in electrical and electronic devices are widely used in spacecraft and nuclear power stations where the polymers are exposed to energetic radioactive rays. The chemical structure can be changed by radiation induced reactions that possibly gives rise to the alteration of characteristics of surface charge, which can enhance the local electrical field and cause surface discharge that damages the insulation. For the safe use of the material, it's necessary to gain a good understanding of radiation effect on surface charge accumulation. In this paper, polyethylene was employed as test sample which was previously irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy / h by using a [sup.60]Co gamma-source. The sample surface was corona charged by applying a series of dc stresses on needle electrode that was set 6 mm above the surface. An electrostatic probe was designed to measure the surface charge density immediately after the charging process. Obtained results show the dependence of surface charge distribution upon the radiation dose varying as a function of the polarity of charging particles. It is suggested that surface charge accumulation depends upon the behavior of localized surface states, which is altered by radiation-induced degradation and cross-linking reactions of the chemical structure. Index Terms--polyethylene, gamma-ray irradiation, surface charge, localized surface states, cross-linking, degradation.

The aging of silicone rubber by gamma irradiation has been investigated. Silicone Rubber flat specimens were aged by gamma irradiation with three different doses and the resistance to tracking on applying ac and dc voltages was examined. The results show that the resistance to tracking under dc voltages is less than that of their ac values. This necessitates a separate standard for determination of tracking resistance under dc voltage. Laboratory examination of material changes together with visual observations and leakage current measurements were also made. The dc stressed samples showed a higher surface degradation compared to those stressed by ac voltages. The erosion depth and contact angle affected by radiation have been studied. The aging of the surface was assessed by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive X-ray Analysis. Index Terms--Silicone rubber (SR), Gamma radiation, y radiation, dc resistance to tracking, contact angle, erosion depth, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy, Energy dispersive X-ray analysis, EDXA, Alumina tri hydrate, ATH.

Dielectric materials used in space on satellite structure may have to cope with strong levels of charging under electron irradiation in space environment. This could lead to potential hazardous discharges and electric arcs and consequent anomalies on the satellite, such as electromagnetic disturbances or, in worst case, the destruction of some on-board systems. These materials need to be tested on-ground to assess their electric behaviour and predict any risk of failure in space environment. The SIRENE facility allows the simulation of geostationnary orbit electron environment and the evaluation of charging capabilities of material samples. We demonstrate, in this paper, that polyimide and polytetrafluoroethylene samples, commonly used in space, are submitted to potentially high radiation induced conductivity or resistivity and electrical ageing under radiation dose in this environment. These physical mechanisms can either reduce the charging level, as observed for polyimide, or dramatically enhance the electric surface potential and the charging kinetics, as seen on polytetrafluoroethylene, leading to high risk of discharge. Index Terms--Space materials, Electron irradiation, Dose Effect, Radiation Induced Conductivity (RIC)

Graphene nanoribbons can exhibit either quasi-metallic or semiconducting behavior, depending on the atomic structure of their edges. Thus, it is important to control the morphology and crystallinity of these edges for practical purposes. We demonstrated an efficient edge-reconstruction process, at the atomic scale, for graphitic nanoribbons by Joule heating. During Joule heating and electron beam irradiation, carbon atoms are vaporized, and subsequently sharp edges and step-edge arrays are stabilized, mostly with either zigzag- or armchair-edge configurations. Model calculations show that the dominant annealing mechanisms involve point defect annealing and edge reconstruction.

Influences of pre-irradiation and thermal annealing on E' defect concentration are studied by measuring E' centers and optical absorptions using ESR and spectrophotometer, respectively. The results show that the E' defect concentration decreases significantly when silica glass is pre-irradiated by [gamma] rays and a subsequent thermal annealing. The effect of thermal annealing on the E' concentration has also been investigated for the temperature from 300[degrees]C to 1300[degrees]C. It is found from the ESR spectrum that the anti-irradiated property of the silica glass can be improved when the thermal annealing temperature is larger than 700[degrees]C. These results have been proved by optical absorption spectra. Index Terms---[gamma] irradiation, E' concentration, electron spin resonance, optical absorption, thermal annealing.

3D pixel sensors are a novel type of silicon detector designed for High Energy Physics and other applications. Their features include high spatial resolution and radiation tolerance. The design consists of alternating rows of n- and p-type columns in a p-type substrate. Capacitance data are presented for 3D pixel devices characterized after exposure to various fluences of 55 MeV protons. Simulations and two methods for the measurement of the inter-electrode capacitance as a function of input signal frequency are shown. Index Terms--3D, capacitance, irradiation, pixel, silicon.

Dark current spectroscopy is used to directly investigate deep-level traps induced by alpha particle irradiation in charge-coupled devices, at trap concentrations as low as ~2 x [10.sup.7] [cm.sup.-3]. The irradiated devices have long dark current histogram tails that are quantized at long imager integration times. This quantization is due to the discrete nature of the distribution of the radiation-induced traps within the device pixels. Four distinct traps, with different dark current generation rates, are found and characterized in terms of their activation energies and capture cross-sections. Two of the traps, identified as the divacancy and the E-center (phosphorus-vacancy), have the highest concentrations and generation rates and are the main constituents of the irradiation tails. The origin of these irradiation tails is explained as a superposition of peaks formed by pixels that contain from a single deep-level trap to multiple traps of the same or different types. Divacancy annealing is shown to result in the formation of four additional traps, which are tentatively attributed to vacancy-oxygen, vacancy-hydrogen, and high-order silicon-vacancy complexes. Index Terms--Annealing, CCD, irradiation, traps.

A new method for the synthesis of cyclic peptide analogues is developed. Prototypical substrates are prepared by coupling preformed peptides with the acid chloride of N-phthalimidoglycine. Irradiation of these substrates results in the generation of cyclic peptide analogues in modest to good yields.

The visible-light irradiation of the system Rivoflavin plus 3-hydroxyflavone or plus 7-hydroxyflavone, under aerobic conditions, produces a series of competitive processes that depend on the relative concentrations of the pigment and the flavones. The picture comprises photochemical mechanisms that potentially operate in nature. They mainly include the quenching of Rf singlet ([sup.1][Rf.sup.*]) and triplet ([sup.3][Rf.sup.*]) excited states (with bimolecular rate constants in the order of [10.sup.9] [M.sup.-1] [s.sup.-1]) and superoxide radical anion-mediated reactions. The participation of the oxidative species singlet molecular oxygen was not detected. The overall result shows chemical transformations in both Rf and 3-hydroxyflavone. No experimental evidence was found indicating any chemical reaction involving 7-hydroxyflavone. The fate of the pigment also depends on the amount of the dissolved flavonoid. At 50 mM concentrations of these compounds or higher, practically no photochemistry occurs, owing to the extensive quenching of [sup.1][Rf.sup.*]. When the concentration of the flavones is in the mM range or lower, [sup.3][Rf.sup.*] is photogenerated. Then, the excited triplet species can be quenched mainly by the flavones through an electron-transfer process, yielding the semireduced pigment. The latter interacts with dissolved oxygen producing [O.sub.2.sup.* -], which reacts with both the pigment and 3-hydroxyflavone. In summary, 3-hydroxyflavone and 7-hydroxyflavone participate in the generation of superoxide ion in an Rf-sensitized process, and simultaneously 3-hydroxyflavone constitutes a degradable quencher of the oxidative species. Key words: flavones, riboflavin, sensitization, singlet molecular oxygen, superoxide radical anion.

The identification of antigens associated with tumor destruction is a major goal of cancer immunology. Vaccination with irradiated tumor cells engineered to secrete granulocyte-macrophage colony stimulating factor generates potent, specific, and long-lasting antitumor immunity through improved tumor antigen presentation by dendritic cells and macrophages. A phase I clinical trial of this immunization strategy in patients with disseminated melanoma revealed the consistent induction in distant metastases of dense T and B cell infiltrates that effectuated substantial tumor necrosis and fibrosis. To delineate the target antigens of this vaccine-stimulated tumor destruction, we screened a melanoma cDNA expression library with postimmunization sera from a long-term responding patient (K030). High-titer IgG antibodies recognized melanoma inhibitor of apoptosis protein (ML-IAP), a caspase antagonist containing a single baculoviral IAP repeat and a COOH-terminal RING domain. Although K030 harbored antibodies to ML-IAP at the time of study entry, multiple courses of vaccination over 4 years increased antibody titers and elicited isotype switching. Moreover, lymphocyte infiltrates in necrotic metastases included [CD4.sup.+] and [CD8.sup.+] T cells specific for ML-IAP, as revealed by proliferation, tetramer, enzyme-linked immunospot, and cytotoxicity analysis. Whereas melanoma cells in densely infiltrated lesions showed strong ML-IAP expression by immunohistochemistry, lethal disease progression was associated with the loss of ML-IAP staining and the absence of lymphocyte infiltrates. These findings demonstrate that ML-IAP can serve as a target for immune-mediated tumor destruction, but that antigen-loss variants can accomplish immune escape.

Research has been conducted on the adenine major oxidation products, N (super)6 -formyl- and N (super)6 -acetyladenine. The formation mechanisms of these products have been investigated and the details are reported.

Tetrakis(trimethylsily)tetrahedrane is synthesized upon irradiation of tetrakis(trimethylsilyl)cyclobutadiene, which can be prepared either by thermal nitrogen elimination from trimethylsilyl[1,2,3-tris(trimethylsilyl)-2-cycloprop-1-enyl]diazomethane or by mild oxidation of cyclobutadiene dianion with 1,2-dibromoethane. Irradiation of tetrakis(trimethylsilyl)cyclobutadiene, which is synthesized by using two completely different routes at low temperature for a long time, affords tetrakis(trimethylsilyl)tetrahedrane.

A one-step preconcentration method using two columns in series was used to partition trace metals in natural waters into several operationally defined fractions. The water passed through a Chelex-100 cation exchange column to collect dissolved labile trace metals and then through an AG MP-1 macroporous resin column to collect trace metals complexed with natural organic matter. A third fraction (inert) was obtained from the difference between total dissolved trace metal concentrations, determined after IN irradiation of a separate aliquot, and the sum of the fractions retained on the two columns. This analytical scheme was successfully applied to the determination of Al, Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn in river waters collected from across the state of Texas. Trace metal partitioning between fractions was found to be stable for at least 8 days after the addition of ammonium acetate buffer (pH 5.5). In most samples collected from relatively pristine sections of Texas rivers, the sum of fractions retained on the two columns accounted for better than 80% of the total dissolved trace metal concentrations. In rivers where anthropogenic inputs were more evident (San Antonio and Trinity Rivers), the inert fraction became pronounced, in some cases accounting for up to 95% of the total dissolved concentrations. The preconcentrate is free of matrix interference and can be easily analyzed by atomic absorption spectrometer or inductively coupled plasma mass spectrometer. Using a 1-L sample allows preconcentration factors of 150 or higher for both labile and organic fractions, and therefore, trace metal concentrations and speciation in natural waters at ambient levels can be accurately and precisely determined.

Soil microorganisms are an important and labile component of soil organic matter. We investigated the feasibility of measuring soil microbial biomass using microwave irradiation as a rapid and nontoxic alternative to chloroform fumigation. The efficacy of microwave irradiation was affected by the distribution pattern and location of soil samples in the oven, the amount of soil, soil moisture content, irradiation time, and soil properties. To ensure uniform and consistent microwave application to soil samples, we modified the microwave treatment procedure (i) by using a round sample rack to improve the uniformity of microwave delivery; (ii) by adjusting the moisture of different soils to the same percentage of their weight; (iii) by using a constant sample weight and irradiation time; and (iv) by grouping soil samples according to their day contents. The results using 30 Australian soils, with a wide range in soil properties, showed that organic C released by microwave irradiation had weak or no correlation with the microbial biomass C measured by chloroform-fumigation extraction, chloroform-fumigation incubation, and substrate-induced respiration methods; while the correlations between the measurements of the three conventional methods were generally close. The increase in extractable C after microwave treatment was often accompanied by an increase in the optical density of the soil extract at 410 nm, which was indicative of the liberation of humified substances by microwave irradiation. We conclude that the organic C liberated from soil by microwave irradiation may contain an appreciable portion of nonbiomass compounds.

Amorphous alloys were studied to determine the short range order modifications induced by swift heavy ion irradiation.

Microlens formation in quantum dot glasses is observed under continuous wave laser irradiation.

The uv-pumped subpicosecond transient reflectivity was used in the measurement of the carrier and thermal dynamics in the region of 60 nm from a silicon wafer surface. The carrier diffusion was found to be confined in the subsurface. Ion implantation resulted to an increase in the carrier recombination rate. Two dimensional mappings, from which images of the surface restricted carrier diffusion and heat generation were achieved, were obtained by scanning the sample.

The utilization of neurons and protons to irradiate single crystals made of yttrium barium copper oxides and the estimation of their critical current and critical temperature is discussed. A Quantum Design superconductor quantum interference device magnenometer was used to measure magnetization hysteresis. Comparable critical currents were exhibited by the irradiated single crystals after irradiation.

The utilization of ultrasonic irradiation for the oxidation of hydrogen solution in oxic aqueous solutions over a range of applied power is discussed. Sulfide ion specific electrode were used to measure sulfide concentrations. Sonification, sample withdrawal and multiple analysis were used for the kinetic runs. It was found that rapid oxidation will result from the ultrasonic irradation of hydrogen sulfide in water.

Research has been conducted on 1,3-dipolar cycloaddition of organic azides to acetylenic amides. Results demonstrate that this cycloaddition carried out under solvent-free microwave irradiation has produced N-substituted C-carbamoyl-1,2,3-triazoles.

We have developed an irradiation technique that allows us to fabricate sets of submicron, planar magnetic nanostructures exhibiting perpendicular magnetization and very reproducible coercivity. The method is based on local 10-keV He ion irradiation of Co[Pt.sub.3] alloys with initial perpendicular magnetization. Irradiation reduces the magneto-crystalline anisotropy in the matrix area around the dots. Irradiation fluence is chosen such that narrow stripes appear, creating demagnetized areas, that surround the dots. The magnetization reversal process of these dots exhibit special features since no nucleation event is ever required. Domain walls are injected from the interdot space, which acts as a domain wall reservoir. The dot coercivity in thus a propagation field, ensuring a weak spread of coercivity. Index Terms--Domain wall reservoir, ion irradiation, magnetic force microscopy, magnetic nanostructures.

The study presented shows that partial chemical ordering can be obtained at moderate processing temperatures by using post growth ion bombardment. The changes on the magnetic hysteresis loops are compatible with the expected perpendicular magnetic anisotropy increase.

The utilization of real time reflectivity measurements at the HeNe laser wavlength in the characterization of solid-liquid transition induced in antimony at 193 nm by pulsed laser irradiation is discussed. Reflectivity transients at energy densities above the melting threshold were analyzed. It was found that the melting for energy densities below 150 mJ cm-2 proceeds inhomogenously.

Research has been conducted on imine-substituted Fischer carbene complexes. The authors have investigated the photoreaction between these complexes and alkynes at theoretical and experimental levels, and have proposed the mechanism accounting for the experimental findings.

The author reviews the publications on matrix-assisted laser desorption ionizationevents. The topics of interest include the analysis of irradiation parameters, material parameters, and the plume dynamics.

We have developed an ion irradiation technique that allows us to tune the magnetic properties of several magnetic alloys which are considered as promising candidates for ultra-high density magnetic recording such as FePd, FePt and Co[Pt.sub.3] films. Depending both on the initial microstructure of the films and temperature used during irradiation the chemical order and the resulting magnetic anisotropy can be either increased or decreased in a very controlled way. We discuss the possible mechanisms involved in ordering processes under irradiation. Index Terms--Anisotropy, chemical order, irradiation, magnetic alloys.

A compact single ion irradiation system has been developed to examine energetic particle effects on materials and devices. The system has been constructed by use of commercially available and inexpensive standard components and can be easily recomposed according to beam requirements for various irradiation experiments. The beam adjustment was automatically performed by help of a computer program based on a modified SIMPLEX method. The beam performances of the system, i.e., pulse width, the number of ions included in one pulse and beam size were examined by use of a microchannel plate, a Si-SSD, a CCD image sensor and a CR-39 track detector, respectively. A beam of a single ion, 1 nsec in pulse width and several [micro]m in diameter has been successfully produced by this system.

The scanning-beam technique for measuring the response of a detector to an irradiance is analyzed. With this method the irradiance responsivity is determined by integration of the spatial responsivity. Since in practice the integration is approximated by a summation over steps with a finite step size, errors are introduced. It is shown both theoretically and experimentally that the error vanishes when the reciprocal step size lies beyond the diffraction limit. Furthermore, comparison shows that experiment and theory are in good agreement. [C] 2000 Optical Society of America OCIS codes: 120.3940, 120.5630, 000.4430, 120.1880, 050.1940, 070.2590.

The isochronal anneal technique used to predict isothermal anneal behavior of MOS devices is analyzed as a function of experimental parameters (bias during irradiation and anneal). This methodology is applied to different oxide types (hardened and unhardened) with different thickness. Net oxide trapped charge is estimated through I-V or C-V measurements, and electron and hole contributions are determined using the TSC technique. The effects of detrapping of trapped holes and compensating electrons are discussed. The prediction of long term post irradiation response can be accurately done when anneals are performed under positive bias. This prediction is more complex for other bias conditions. The difficulty is related to competitive effects of trapped hole annealing and buildup of compensating electrons as a function of temperature. To enable a precise modeling of long term annealing, a complete model must include, among other things, compensation of holes through tunneling, and/or thermally injected electrons.