Science.gov

Sample records for 280-320 nm radiation

  1. Immunosuppressive effects of ultraviolet (280-320 nm) radiation and psoralen plus ultraviolet (320-400 nm) radiation in mice.

    PubMed

    Kripke, M L

    1982-07-01

    Contact hypersensitivity (CHS), a cell-mediated immunologic reaction, can be induced in mice by application of a contact-sensitizing chemical to the shaved skin. Exposing the animals to UV radiation from FS40 sunlamps inhibits this immune response. This inhibition is systemic, since the sensitizer need not be applied to the irradiated site of the animal. The mechanism whereby UV radiation prevents CHS appears to involve the production of suppressor T-lymphocytes. Recent evidence suggests that UV exposure of mice alters the way in which certain antigens are processed, and this altered processing or presentation of antigen results in the activation of the suppressor cell pathway, rather than leading to immunization. Treatment of mice with a photosensitizer, psoralen, plus UV (320-400 nm) radiation also suppresses CHS systemically, but whether the cellular mechanisms are the same as those underlying the suppression from the shorter UV wavelengths remains to be determined. The possible role of these immunosuppressive events in photocarcinogenesis is discussed. PMID:6212709

  2. Pyridoxine supplementation protects mice from suppression of contact hypersensitivity induced by 2-acetyl-4-tetrahydroxybutylimidazole (THI), ultraviolet B radiation (280-320 nm), or cis-urocanic acid.

    PubMed

    Reeve, V E; Bosnic, M; Boehm-Wilcox, C; Cope, R B

    1995-03-01

    Evidence exists implicating the epidermal ultraviolet B (UVB) photoproduct cis-urocanic acid as an immunogenic mediator of the systemic suppression of T cell-mediated immunity by UVB exposure. Cis-urocanic acid appears to act via histamine receptor pathways, and histamine receptor antagonists and other imidazole ring compounds may modify its immune suppressing action. A component of the food coloring substance ammonia caramel, 2-acetyl-4-tetrahydroxybutylimidazole (THI), which is known to cause lymphopenia in rats, appears to suppress immunity by a similar pathway when the contact hypersensitivity reaction has been the immune function assay in mice. The induction of lymphopenia in rats by THI is inhibited by the vitamin pyridoxine. This study demonstrates that the suppression of contact hypersensitivity in mice by UVB radiation, cis-urocanic acid, or THI is strongly inhibited by supplemental pyridoxine, fed at 30 mg/kg diet, in comparison with the normal diet, which supplies 7 mg pyridoxine/kg diet. These results suggest that pyridoxine competes with cis-urocanic acid and THI for the same binding site or receptor, which we postulate to be a histamine-like T lymphocyte receptor, and that a role may exist for the control of photoimmunosuppression by this vitamin. PMID:7872221

  3. 15 CFR 280.320 - Maintenance of the certificate of recordal.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS FASTENER QUALITY Recordal of Insignia Post-Recordal Maintenance § 280.320 Maintenance...

  4. 15 CFR 280.320 - Maintenance of the certificate of recordal.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS FASTENER QUALITY Recordal of Insignia Post-Recordal Maintenance § 280.320 Maintenance...

  5. 15 CFR 280.320 - Maintenance of the certificate of recordal.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS FASTENER QUALITY Recordal of Insignia Post-Recordal Maintenance § 280.320 Maintenance...

  6. 15 CFR 280.320 - Maintenance of the certificate of recordal.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS FASTENER QUALITY Recordal of Insignia Post-Recordal Maintenance § 280.320 Maintenance...

  7. 15 CFR 280.320 - Maintenance of the certificate of recordal.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE ACCREDITATION AND ASSESSMENT PROGRAMS FASTENER QUALITY Recordal of Insignia Post-Recordal Maintenance § 280.320 Maintenance...

  8. Solar ultraviolet radiation exclusion increases soybean internode lengths and plant height

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean [Glycine max (L.) Merr.] cultivars Williams-82 and Maverick were grown in a polycarbonate greenhouse, a glass greenhouse, and outdoors (during daytime) to investigate the effect of (i) exclusion of both solar UV-B radiation (280-320 nm) and UV-A radiation (320-400 nm), (ii) exclusion of sola...

  9. EFFECTS OF ULTRAVIOLET-B RADIATION ON PLANT COMPETITION IN TERRESTRIAL ECOSYSTEMS

    EPA Science Inventory

    Evidence regarding the interaction of ultraviolet-B (UV-B, 280-320 nm) radiation and plant competition in terrestrial ecosystems is examined. The competitive interactions of some species pairs were affected even by ambient solar UV-B radiation (as exists without ozone depletion),...

  10. INTRASPECIFIC VARIATION IN SENSITIVITY TO UV-B RADIATION IN RICE

    EPA Science Inventory

    Twenty-two cultivars of rice (Oryza sativa L.) from diverse origins were grown under greenhouse conditions and exposed to ultraviolet-B radiation (UV-B; 280-320 nm) simulating a 5% reduction in stratospheric ozone in spring for the Philippines (14 degrees N lat.) to evaluate grow...

  11. EFFECTS OF ENHANCED ULTRAVIOLET-B RADIATION ON YIELD, AND DISEASE INCIDENCE AND SEVERITY FOR WHEAT UNDER FIELD CONDITIONS

    EPA Science Inventory

    The influence of enhanced UV-B radiation (280-320 nm) on wheat (Triticum aestivum cv. 'Florida 301') yield, and disease incidence and severity was investigated for two growing seasons under field conditions. Three levels of UV-B enhancement, simulating 8,12 and 16% stratospheric ...

  12. RESPONSE OF OXIDATIVE STRESS DEFENSE SYSTEMS IN RICE (ORYZA SATIVA) LEAVES WITH SUPPLEMENTAL UV-B RADIATION

    EPA Science Inventory

    The impact of elevated ultraviolet-B radiation (UV-B, 280-320 nm) on membrane systems and lipid peroxidation, and possible involvement of active oxygen radicals was investigated in leaves of two UV-B susceptible rice cultivars (Oryza sativa L. cvs IR74 and Dular). Rice seedlings ...

  13. EFFECTS OF ULTRAVIOLET-B RADIATION ON PLANTS DURING MILD WATER STRESS. EFFECTS ON PHOTOSYNTHETIC RECOVERY AND GROWTH IN SOYBEAN

    EPA Science Inventory

    Soybean was grown from seed in a greenhouse under ultraviolet-B (UV-B, 280-320 nm) radiation supplied by filtered FS-40 sunlamps. On a weighted, total daily dose basis these plants received either 0 (control) or 2875 effective J m-2 day-1 UV-BBE. When weighted with the generalize...

  14. Icecolors `93: Epilithic productivity by microalgae exhibits a potentially high sensitivity to natural levels of ultraviolet-B radiation

    SciTech Connect

    Evans, T.; Roll, S.; Golden, B.

    1994-12-31

    Increased ultraviolet-B [UV-B, 280-320 nanometers (nm)] radiation associated with the depletion of stratospheric ozone (O{sub 3}) over Antarctica during the austral spring has a negative impact on phytoplankton and sea-ice algae productivity. The Icecolors 1993 expedition documented the potential impact of ultraviolet radiation (UVR) on littoral microalgae (lithophytes), which are almost always highly exposed to deleterious light effects. 7 refs., 2 figs., 1 tab.

  15. Radiation Status of Sub-65 nm Electronics

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.

    2011-01-01

    Ultra-scaled complementary metal oxide semiconductor (CMOS) includes commercial foundry capabilities at and below the 65 nm technology node Radiation evaluations take place using standard products and test characterization vehicles (memories, logic/latch chains, etc.) NEPP focus is two-fold: (1) Conduct early radiation evaluations to ascertain viability for future NASA missions (i.e. leverage commercial technology development). (2) Uncover gaps in current testing methodologies and mechanism comprehension -- early risk mitigation.

  16. Radiation Tolerance of 65nm CMOS Transistors

    DOE PAGESBeta

    Krohn, M.; Bentele, B.; Christian, D. C.; Cumalat, J. P.; Deptuch, G.; Fahim, F.; Hoff, J.; Shenai, A.; Wagner, S. R.

    2015-12-11

    We report on the effects of ionizing radiation on 65 nm CMOS transistors held at approximately -20°C during irradiation. The pattern of damage observed after a total dose of 1 Grad is similar to damage reported in room temperature exposures, but we observe less damage than was observed at room temperature.

  17. Radiation Failures in Intel 14nm Microprocessors

    NASA Technical Reports Server (NTRS)

    Bossev, Dobrin P.; Duncan, Adam R.; Gadlage, Matthew J.; Roach, Austin H.; Kay, Matthew J.; Szabo, Carl; Berger, Tammy J.; York, Darin A.; Williams, Aaron; LaBel, K.; Ingalls, James D.

    2016-01-01

    In this study the 14 nm Intel Broadwell 5th generation core series 5005U-i3 and 5200U-i5 was mounted on Dell Inspiron laptops, MSI Cubi and Gigabyte Brix barebones and tested with Windows 8 and CentOS7 at idle. Heavy-ion-induced hard- and catastrophic failures do not appear to be related to the Intel 14nm Tri-Gate FinFET process. They originate from a small (9 m 140 m) area on the 32nm planar PCH die (not the CPU) as initially speculated. The hard failures seem to be due to a SEE but the exact physical mechanism has yet to be identified. Some possibilities include latch-ups, charge ion trapping or implantation, ion channels, or a combination of those (in biased conditions). The mechanism of the catastrophic failures seems related to the presence of electric power (1.05V core voltage). The 1064 nm laser mimics ionization radiation and induces soft- and hard failures as a direct result of electron-hole pair production, not heat. The 14nm FinFET processes continue to look promising for space radiation environments.

  18. Effects of solar ultraviolet photons on mammalian cell DNA. [UVA (320-400 nm):a2

    SciTech Connect

    Peak, M.J.; Peak, J.G.

    1991-01-01

    This document presents information on the possible mechanisms of carcinogenesis caused by UVA (ultraviolet radiation in the 320--400 nm region). Most studies showing the carcinogenic effects of ultraviolet light have concentrated on UVB (280--320 nm). UVA had been considered harmless even though it penetrates biological tissues better than UVB. Recently, it has become apparent that UVA is also capable of causing damage to cellular DNA. This was unexpected because the DNA UV absorption spectrum indicates a negligible probability that photons of wavelengths longer than 320 nm will be directly absorbed. The most common defects induced in DNA by UVB are pyrimidine photoproducts, such as thymidine dimers. UVA photons produce defects resembling those caused by ionizing radiations: single- and double-strand breaks, and DNA-protein crosslinks. This paper also discusses the role of DNA repair mechanisms in UVA-induced defects and the molecular mechanisms of UVA damage induction. 38 refs. (MHB)

  19. Partial inhibition of in vitro pollen germination by simulated solar ultraviolet-B radiation

    SciTech Connect

    Flint, S.D.; Caldwell, M.M.

    1984-01-01

    Pollen from four temperate-latitude taxa were treated with UV radiation in a portion of the UV-B (280-320 nm) waveband during in vitro germination. Inhibition of germination was noted in this pollen compared to samples treated identically except for the exclusion of the UV-B portion of the spectrum. Levels similar to maximum solar UV-B found in temperate-latitude areas failed to inhibit pollen germination significantly, while levels similar to maximum solar UV-B found in equatorial alpine locations caused partial inhibition of germination in three of the four taxa examined.

  20. Inactivation of conidia of Paecilomyces fumosoroseus by near-ultraviolet (UVB and UVA) and visible radiation.

    PubMed

    Fargues, J; Rougier, M; Goujet, R; Smits, N; Coustere, C; Itier, B

    1997-01-01

    The detrimental effects of solar radiation, especially the ultraviolet waveband, on quiescent conidia of Paecilomyces fumosoroseus were investigated. Conidia were irradiated by a high-intensity source, which emitted a continuous spectrum from 270 to 1100 nm and which was equipped with long-pass filters to block short wavelengths below 280, 295, 320, or 400 nm. After irradiation, conidia were tested for germinability, survival, and infectivity toward Spodoptera frugiperda larvae. It was demonstrated that the detrimental effects of light depended on irradiance in the shortest wavelengths. The UVB (280-320 and 295-320 nm) appeared to be the most detrimental part of natural radiation, although UVA (320-400 nm) was also harmful. Visible and near infrared radiations were less harmful than UV. Our results demonstrate that the irradiance of the UVB waveband should be considered as the pertinent factor for the detrimental effects of sunlight on the persistence of conidia of entomopathogenic fungi in insolated environments. PMID:9028931

  1. Morphological responses of crop and weed species of different growth forms to ultraviolet-B radiation

    SciTech Connect

    Barnes, P.W.; Flint, S.D.; Caldwell, M.M. )

    1990-10-01

    Recent evidence of a general, global decline of stratospheric ozone has heightened concern about possible ecological consequences of increases in solar ultraviolet-B (UV-B, 280-320 nm) radiation resulting from ozone depletion. The influence of UV-B radiation (280-320 nanometers) on the morphology of 12 common dicot and monocot crop or weed species was examined to determine whether any common responses could be found that might, in turn, be useful in predicting possible changes in competitive balance under solar UV-B enhancement. Under glasshouse conditions, UV-B exposure (simulating a 20% reduction in stratospheric ozone at Logan, Utah) was found to reduce leaf blade and internode lengths and increase leaf and axillary shoot production in several species. Overall, the directions of these trends were similar in the majority of species that exhibited a significant response. These morphological changes occurred without any significant reduction in total shoot dry matter production. There was no clear distinction in the response of crops and weeds, though monocots were found to be generally more responsive than dicots. Previous work in dense canopies has shown that the photomorphogenetic effects of UV-B alter leaf placement and thereby influence competition for light. Our results suggest that, under these conditions, changes in competitive balance resulting from increased UV-B might be expected more frequently when monocots are involved in mixtures, rather than mixtures of only dicots.

  2. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  3. Stratospheric ozone depletion between 1979 and 1992: implications for biologically active ultraviolet-B radiation and non-melanoma skin cancer incidence.

    PubMed

    Madronich, S; de Gruijl, F R

    1994-05-01

    The depletion of stratospheric ozone (O3) has predictable implications for increases in biologically damaging solar ultraviolet-B radiation (UVB, 280-320 nm) reaching the earth's surface. A radiative transfer analysis of satellite-based O3 measurements between January 1979 and December 1992 shows that surface UVB levels increased substantially at all latitudes except the tropics, if other factors such as cloud cover and local pollutant levels have remained constant over this period. Exposure to UVB radiation is known to induce basal cell and squamous cell skin cancers, and dose-response relationships derived from epidemiological data can be combined with the UVB enhancements to estimate the seasonal and latitudinal distribution of future expected increases in the incidence of these cancers. PMID:8041809

  4. Gracilaria bursa-pastoris (Gmelin) Silva extract attenuates ultraviolet B radiation-induced oxidative stress in human keratinocytes.

    PubMed

    Piao, M J; Kim, K C; Zheng, J; Yao, C W; Cha, J W; Kang, H K; Yoo, E S; Koh, Y S; Ko, M H; Lee, N H; Hyun, Jin Won

    2014-01-01

    The purpose of this study was to assess the protective effects of an ethanol extract derived from the red alga Gracilaria bursa-pastoris (Gmelin) Silva (GBE) on ultraviolet B (UVB)-irradiated human HaCaT keratinocytes. GBE exhibited scavenging activity against intracellular reactive oxygen species that were induced by either hydrogen peroxide or UVB radiation. In addition, both the superoxide anion and the hydroxyl radical were scavenged by GBE in cell-free systems. GBE absorbed light in the UVB range (280-320 nm) of the electromagnetic spectrum and lessened the extent of UVB-induced oxidative damage to cellular lipids, proteins, and DNA. Finally, GBE-treated keratinocytes showed a reduction in UVB-induced apoptosis, as exemplified by fewer apoptotic bodies. These results suggest that GBE exerts cytoprotective actions against UVB-stimulated oxidative stress by scavenging ROS and absorbing UVB rays, thereby attenuating injury to cellular constituents and preventing cell death. PMID:24579808

  5. Infrared Luminescence at 1010 nm and 1500 nm in LiNbO3:Er3+ Excitted by Short Pulse Radiation at 980 nm

    NASA Astrophysics Data System (ADS)

    Kokanyan, E. P.; Demirkhanyan, G. G.; Steveler, E.; Rinnert, H.; Aillerie, M.

    Luminescence of LiNbO3:Er3+ crystal at a wavelength of 1010 nm and 1500 nm under pulsed excitation of different power at a wavelength of 980 nm are experimentally and theoretically studied. It is revealed, that the main part of the absorbed energy gives rise to the luminescence at 1500 nm. Considered concentrations of Er3+ impurity ions allow to exclude cooperative processes in the impurity subsystem. The experimental results are interpreted in the framework of a three electronic levels system, assuming that the population of the higher lasing level 4I13/2 in the crystal under study is caused by relaxation processes from the excited level. It is shown that for obtaining of a laser radiation at about 1500 nm one can effectively use a pulse-pumping at 980 nm with a power density in a range of 50 ÷ 60 MW/cm2.

  6. Effects of long-term, elevated ultraviolet-B radiation on phytochemicals in the bark of silver birch (Betula pendula).

    PubMed

    Tegelberg, Riitta; Aphalo, Pedro J; Julkunen-Tiitto, Riitta

    2002-12-01

    Long-term outdoor experiments were conducted to investigate the effects of elevated ultraviolet-B (UV-B, 280-320 nm) radiation on secondary metabolites (phenolics and terpenoids) and the main soluble sugars (sucrose, raffinose and glucose) in the bark of silver birch (Betula pendula Roth) saplings. Saplings were exposed to a constant 50% increase in erythemal UV irradiance (UV-B(CIE); based on the CIE (International Commission on Illumination) erythemal action spectrum) and a small increase in UV-A radiation (320-400 nm) for three growing seasons in an irradiation field in central Finland. Two control groups were used: saplings exposed to ambient radiation and saplings exposed to slightly increased UV-A radiation. Concentrations of sucrose, raffinose and glucose in bark were higher in UV-treated saplings than in saplings grown in ambient radiation, indicating that stem carbohydrate metabolism was changed by long-term elevated UV radiation. Saplings in the elevated UV-A + UV-B radiation treatment and the UV-A radiation control treatment had significantly increased concentrations of certain UV-absorbing phenolics, such as salidroside, 3,4'-dihydroxypropiophenone-3-glucoside, (+)-catechin and (-)-epicatechin compared with saplings in ambient radiation. In contrast, the radiation treatments had no effect on the non-UV-B-absorbing terpenoids, papyriferic acid and deacetylpapyriferic acid. We conclude that plant parts, in addition to leaves, accumulate specific phenolic UV-filters in response to UV radiation exposure. PMID:12464579

  7. Porcine dermal lesions produced by 1540-nm laser radiation pulses

    NASA Astrophysics Data System (ADS)

    Roach, William P.; Johnson, Thomas E.

    2001-07-01

    Completion of recent studies within our group indicates a breed-based difference in dermal response to 1540 nm 0.8 millisecond laser pulses. Laser exposure to Yucatan Mini- Pigs (highly pigmented skin) and Yorkshire pigs (lightly pigmented skin) demonstrate statistical differences between the ED50's of the two breeds. Laser delivery is accomplished using an Er:Glass system producing 1540 nm of light at millisecond exposure times and in the range of 5 to 95 J/cm2. Dermal lesion development was evaluated for acute, 1 hour, and 24-hour post exposure presentation. Our data contradicts the theory that water absorption is the sole mechanism of dermal tissue damage observed from 1540 nm laser exposures, as skin chromophores appear to play a role in lesion development.

  8. Brain lesion induced by 1319nm laser radiation

    NASA Astrophysics Data System (ADS)

    Yang, Zaifu; Chen, Hongxia; Wang, Jiarui; Chen, Peng; Ma, Ping; Qian, Huanwen

    2010-11-01

    The laser-tissue interaction has not been well defined at the 1319 nm wavelength for brain exposure. The goal of this research effort was to identify the behavioral and histological changes of brain lesion induced by 1319 nm laser. The experiment was performed on China Kunming mice. Unilateral brain lesions were created with a continuous-wave Nd:YAG laser (1319nm). The brain lesions were identified through behavioral observation and histological haematoxylin and eosin (H&E) staining method. The behavior change was observed for a radiant exposure range of 97~773 J/cm2. The histology of the recovery process was identified for radiant exposure of 580 J/cm2. Subjects were sacrificed 1 hour, 1 week, 2 weeks, 3 months, 7 months and 13 months after laser irradiation. Results showed that after laser exposure, behavioral deficits, including kyphosis, tail entasia, or whole body paralysis could be noted right after the animals recovered from anesthesia while gradually disappeared within several days and never recurred again. Histologically, the laser lesion showed a typical architecture dependent on the interval following laser treatment. The central zone of coagulation necrosis is not apparent right after exposure but becomes obvious within several days. The nerotic tissue though may persist for a long time, will finally be completely resorbed. No carbonization granules formed under our exposure condition.

  9. Sum frequency generation of UV laser radiation at 266  nm in LBO crystal.

    PubMed

    Nikitin, D G; Byalkovskiy, O A; Vershinin, O I; Puyu, P V; Tyrtyshnyy, V A

    2016-04-01

    We report experimental results of generation at 266 nm in LBO crystal by frequency mixing of the fundamental (1064 nm) and third harmonic (355 nm) of ytterbium pulsed fiber laser radiation. Deep ultraviolet (DUV) output power of 3.3 W at 266 nm was achieved with 14% IR-to-DUV conversion efficiency. UV-induced bulk degradation of LBO crystals was observed and visualized by the dark field method. PMID:27192312

  10. Ultraviolet radiation (UVR) (290-400 nm) radiometry of solar simulation for experimental radiation in drug and chemical photosensitization

    NASA Astrophysics Data System (ADS)

    Young, A. R.; Magnus, I. A.; Gibbs, N. K.

    1982-02-01

    The ultraviolet radiation (UVR) radiometry of solar simulated radiation in a long-term photocarcinogenesis project is described. The methods used were (a) a phototherapy radiometer, (b) an electronic integrating dosimeter, (c) indirect spectroradiometry,and (d) polysulphone and naladixic film badge dosimeters for UV-B (280-315 nm) and UV-A (315-400 nm) radiation, respectively. The merits of the various methods are discussed. The importance of reliable and practical UVR radiometry is emphasised.

  11. Removal of copper oxide from copper surfaces using Q-switched Nd:YAG radiation at 1064 nm, 532 nm, and 266 nm

    NASA Astrophysics Data System (ADS)

    Kearns, Aileen; Fischer, C.; Watkins, Kenneth G.; Glasmacher, Mathias; Steen, William M.; Kheyrandish, H.; Brown, A.

    1997-08-01

    During electronic device fabrication it is necessary to remove the oxides from copper surfaces prior to soldering in order to improve the surface wetability and achieve a good quality solder joint. The usual method of achieving this is by using acids in a flux. The work reported here explores the possibility of removing these oxides by laser cleaning using the harmonics of a Q-switched Nd:YAG laser, a technique which could be incorporated into a industrial laser soldering process. The effect of Q-switched Nd:YAG radiation (5 - 10 ns pulses), at 1064 nm, 532 nm and 266 nm, on the oxidized surface of a copper alloy foil is studied with increasing fluence. In order to successfully compare the effect of increasing fluence at the three wavelengths each area treated was only subjected to one laser pulse. The laser treated surfaces were characterized using optical microscopy, SEM, and surface analysis performed by static secondary ion mass spectrometry (SSIMS). SSIMS and SNMS (secondary neutral mass spectrometry) with mechanical depth profilometry were used to characterize the oxide layer. The reflectivity of the oxidized plates for the three wavelengths was ascertained using a reflectivity spectrometer. Successful cleaning was achieved at all wavelengths, above certain threshold values which defined the lower end of the process operating window for single pulse operation. The threshold for the cleaning process decreased with laser wavelength. Surface melting was evident at the lowest fluences examined for all the wavelengths (< .5 J/cm2). This value is well below the lower end of the process windows of all wavelengths. Microscopic `explosive' features were found at the onset of copper oxide removal possibly resulting from ionization or a plasma induced shock waves. There was some possible evidence of mechanical effects at 1064 nm and 532 nm. Large amounts of sputtered debris was found around the 266 nm craters. A SSIMS analysis was performed on the 532 nm spots. The

  12. Association of amphibians with attenuation of ultraviolet-b radiation in montane ponds

    USGS Publications Warehouse

    Adams, M.J.; Schindler, D.E.; Bury, B.R.

    2001-01-01

    Ambient ultraviolet-b (UV-B) radiation (280-320 nm) has increased at north-temperate latitudes in the last two decades. UV-B can be detrimental to amphibians, and amphibians have shown declines in some areas during this same period. We documented the distribution of amphibians and salmonids in 42 remote, subalpine and alpine ponds in Olympic National Park, Washington, United States. We inferred relative exposure of amphibian habitats to UV-B by estimating the transmission of 305- and 320-nm radiation in pond water. We found breeding Ambystoma gracile, A. macrodactylum and Rana cascadae at 33%, 31%, and 45% of the study sites, respectively. Most R. cascadae bred in fishless shallow ponds with relatively low transmission of UV-B. The relationship with UV-B exposure remained marginally significant even after the presence of fish was included in the model. At 50 cm water depth, there was a 55% reduction in incident 305-nm radiation at sites where breeding populations of R. cascadae were detected compared to other sites. We did not detect associations between UV-B transmission and A. gracile or A. macrodactylum. Our field surveys do not provide evidence for decline of R. cascadae in Olympic National Park as has been documented in Northern California, but are consistent with the hypothesis that the spatial distribution of R. cascadae breeding sites is influenced by exposure to UV-B. Substrate or pond depth could also be related to the distribution of R. cascadae in Olympic National Park.

  13. Inhibition of denitrification by ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Mancinelli, R. L.; White, M. R.

    It has been shown that UV-A (λ = 320- 400 nm) and UV-B (λ = 280 - 320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC # 17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps. fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation.

  14. Inhibition of denitrification by ultraviolet radiation.

    PubMed

    Mancinelli, R L; White, M R

    2000-01-01

    It has been shown that UV-A (lambda=320-400 nm) and UV-B (lambda=280-320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC #17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation. PMID:12038490

  15. IMPACT OF SOLAR ULTRAVIOLET-B RADIATION (290-320 NM) UPON MARINE MICROALGAE

    EPA Science Inventory

    For years scientists and laymen alike have casually noted the impact of solar ultraviolet radiation upon the nonhuman component of the biosphere. Stratospheric ozone functions effectively as an ultraviolet screen by filtering out solar radiation in the 220-320 nm waveband as it p...

  16. Gamma-ray radiation response at 1550 nm of fluorine-doped radiation hard single-mode optical fiber.

    PubMed

    Kim, Youngwoong; Ju, Seongmin; Jeong, Seongmook; Lee, Seung Ho; Han, Won-Taek

    2016-02-22

    We have investigated gamma-ray radiation response at 1550 nm of fluorine-doped radiation hard single-mode optical fiber. Radiation-induced attenuation (RIA) of the optical fiber was measured under intermittent gamma-ray irradiations with dose rate of ~10 kGy/h. No radiation hardening effect on the RIA by the gamma-ray pre-dose was found when the exposed fiber was bleached for long periods of time (27~47 days) at room-temperature. Photo-bleaching scheme upon 980 nm LD pumping has proven to be an effective deterrent to the RIA, particularly by suppressing the incipient RIA due to room-temperature unstable self-trapped hole defects (STHs). Large temperature dependence of the RIA of the optical fiber together with the photo-bleaching effect are worthy of note for reinforcing its radiation hard characteristics. PMID:26907044

  17. Nonthermal radiative transfer of oxygen 98.9 nm ultraviolet emission: Solving an old mystery

    NASA Astrophysics Data System (ADS)

    Hubert, B.; Gérard, J.-C.; Shematovich, V. I.; Bisikalo, D. V.; Chakrabarti, S.; Gladstone, G. R.

    2015-12-01

    Sounding rocket measurements conducted in 1988 under high solar activity conditions revealed that the intensity of thermospheric OI emissions at 98.9 nm presents an anomalous vertical profile, showing exospheric intensities much higher than expected from radiative transfer model results, which included the known sources of excited oxygen. All attempts based on modeling of the photochemical processes and radiative transfer were unable to account for the higher than predicted brightnesses. More recently, the SOHO-Solar Ultraviolet Measurements of Emitted Radiation instrument measured the UV solar flux at high-spectral resolution, revealing the importance of a significant additional source of oxygen emission at 98.9 nm that had not been accounted for before. In this study, we simulate the radiative transfer of the OI-98.9 nm multiplet, including the photochemical sources of excited oxygen, the resonant scattering of solar photons, and the effects of nonthermal atoms, i.e., a population of fast-moving oxygen atoms in excess of the Maxwellian distribution. Including resonance scattering of the 98.9 nm solar multiplet, we find good agreement with the previous sounding rocket observation. The inclusion of a nonthermal oxygen population with a consistent increase of the total density produces a larger intensity at high altitude that apparently better accounts for the observation, but such a correction cannot be demonstrated given the uncertainties of the observations. A good agreement between model and sounding rocket observation is also found with the triplet at 130.4 nm. We further investigate the radiative transfer of the OI-98.9 nm multiplet and the oxygen emissions at 130.4 and 135.6 nm using observations from the STP78-1 satellite. We find a less satisfying agreement between the model and the STP78-1 data that can be accounted for by scaling the modeled intensity within a range acceptable given the uncertainties on the STP78-1 absolute calibration.

  18. Response of five tropical plant species to natural solar ultraviolet-B radiation

    SciTech Connect

    Searles, P.S.; Caldwell, M.M. ); Winter, K. )

    1994-06-01

    The tropical latitudes currently receive high solar ultraviolet-B radiation (UV-B, 280-320 nm) even without ozone depletion. Thus, the influence of natural, present-day UV-B irradiance was examined for three native rainforest tree species and two economically important species on Barro Colorado Island, Panama (9[degrees] N). Solar UV-B radiation conditions were obtained using a UV-B excluding plastic film or a near-ambient UV-B transmitting film over potted plants in a small clearing. Significant differences were often exhibited as increased foliar UV-B absorbing compounds, increased leaf mass pre area, and reduced leaf blade length for plants receiving solar UV-B radiation. Plant height was typically reduced under solar UV-B, but some variation among species in response was seen. Biomass and photosystem II function were generally unaffected. The results provide evidence that tropical vegetation responds to the present level of Solar UV-B radiation. This suggests even a small increase in UV-B radiation with ozone depletion may have biological implications.

  19. Effects of solar ultraviolet radiation on antarctic phytoplankton during springtime ozone depletion

    SciTech Connect

    Villafane, V.E.; Helbling, E.W.; Holm-Hansen, O.

    1994-12-31

    In recent years, much attention has been given to the formation of the seasonal ozone {open_quotes}hole{close_quotes} over Antarctica, with the concomitant increase in ultraviolet-B [UV-B, 280-320-nanometer (nm)] radiation levels. The enhanced UV-B radiation can be very damaging to biological systems and has been shown to cause a significant decrease in rates of primary production. This paper describes the impact of {open_quotes}normal{close_quotes} ultraviolet radiation (UVR), as well as enhanced UV-B radiation, on natural assemblages of phytoplankton as well as on just the nanoplankton fraction cells less than 20 micrometers ({mu}m). The studies also included estimation of the impact of UVR as influenced by the taxonomic composition of the phytoplankton and the mitigating effect of cellular UV-absorbing compounds. All studies were carried out at Palmer Station (64.7{degrees}S 64.1{degrees}W) on Anvers Island from early October to the end of December 1993. This period provided excellent opportunities to document the impact of enhanced UV-B radiation on phytoplankton because the ozone hole was very well developed over Palmer Station in the month of October; column ozone concentrations ranged from 140 to 220 Dobson units (DU). 10 refs, 3 figs.

  20. Hypersensitivity of skin fibroblasts from basal cell nevus syndrome patients to killing by ultraviolet B but not by ultraviolet C radiation

    SciTech Connect

    Applegate, L.A.; Goldberg, L.H.; Ley, R.D.; Ananthaswamy, H.N. )

    1990-02-01

    Basal cell nevus syndrome (BCNS) is an autosomal dominant genetic disorder in which the afflicted individuals are extremely susceptible to sunlight-induced skin cancers, particularly basal cell carcinomas. However, the cellular and molecular basis for BCNS is unknown. To ascertain whether there is any relationship between genetic predisposition to skin cancer and increased sensitivity of somatic cells from BCNS patients to killing by UV radiation, we exposed skin fibroblasts established from unexposed skin biopsies of several BCNS and age- and sex-matched normal individuals to either UV-B (280-320 nm) or UV-C (254 nm) radiation and determined their survival. The results indicated that skin fibroblasts from BCNS patients were hypersensitive to killing by UV-B but not UV-C radiation as compared to skin fibroblasts from normal individuals. DNA repair studies indicated that the increased sensitivity of BCNS skin fibroblasts to killing by UV-B radiation was not due to a defect in the excision repair of pyrimidine dimers. These results indicate that there is an association between hypersensitivity of somatic cells to killing by UV-B radiation and the genetic predisposition to skin cancer in BCNS patients. In addition, these results suggest that DNA lesions (and repair processes) other than the pyrimidine dimer are also involved in the pathogenesis of sunlight-induced skin cancers in BCNS patients. More important, the UV-B sensitivity assay described here may be used as a diagnostic tool to identify presymptomatic individuals with BCNS.

  1. Photosensitivity of a diamond detector to laser radiation in the 220 - 355-nm region

    SciTech Connect

    Lipatov, E I; Panchenko, Aleksei N; Tarasenko, Viktor F; Shein, J; Krishnan, M

    2001-12-31

    The photosensitivity of detectors of laser radiation based on the natural type IIa diamond (Alameda Applied Sciences Corporation, USA) are studied at the wavelengths 222, 308, 337, and 353 nm. The limiting intensities (0.5 - 4 MW cm{sup -2}) of UV laser radiation are determined at which the detectors operate in a linear regime. (laser applications and other topics in quantum electronics)

  2. Modeling ultraviolet-B radiation in a maize canopy

    NASA Astrophysics Data System (ADS)

    Gao, Wei; Grant, Richard H.; Heisler, Gordon M.; Slusser, James R.

    2002-01-01

    A decrease in stratospheric ozone may result in a serious threat to plants, since biologically active short-wavelength ultraviolet-B (UVB 280-320 nm) radiation will increase even with a relatively small decrease in ozone. Experimental work has shown that various cultivars and species respond to UVB in different ways. To determine the physiological effects on plants of any increases in UVB radiation, the irradiances at the potential sensitive plant surface need to be known. Numerical models are needed to calculate UVB irradiance. This paper compares spatially and temporally averaged measurements of UVB canopy transmittance (Tcanopy, irradiance below canopy/irradiance above canopy) to that predicted by three models. Maize was selected as the canopy for the study because direct measurements of leaf area and leaf angle distribution are manageable. The models can be applied to other plants including urban trees, though other methods of characterizing leaf area and angle distributions generally would be used. Using measurements of canopy parameters as inputs to the numerical scheme, the models attempt to simulate the UVB Tcanopy that the UVB sensors measure. The purpose of this paper is: (1) to describe the models developed for calculating UVB irradiances (as measured by UVB Tcanopy) at given positions in maize canopies; and (2) to report the results of experimental tests of the models.

  3. New apparatus with high radiation energy between 320 to 460 nm: physical description and dermatological applications

    SciTech Connect

    Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

    1981-01-01

    A new apparatus (UVASUN 5000) is presented with high radiation energy between 320 to 460 nm. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-A applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.

  4. RADIATION SPECTRUM STATISTICS IN A HIGH-GAIN FREE-ELECTRON LASER AT 266NM.

    SciTech Connect

    STAFTAN, T.; SHEEHY, B.; LOOS, H.; YU, L.H.; MURPHY, J.B.; KRINSKY, S.; ROSE, J.; WATANABE, T.; LIU, D.; WANG, X.J.

    2005-08-21

    High Gain Harmonic Generation FEL is in operations at the DUV-FEL facility (BNL). During HGHG FEL characterization we have measured a set of data demonstrating basic properties of the FEL radiation and compared them with analytic calculations [1]. This paper describes continuation of characterization of the HGHG FEL radiation output, based on the spectral measurements. We discuss analysis of an experiment at which the tunability concept of a seeded FEL with a fixed seed wavelength has been verified [2]. During the experiment we recorded about 200 radiation spectra corresponding to different energy chirps in the electron beam. We have analyzed this set of spectral data to obtain statistical properties of HGHG radiation. Correlations and trends in the radiation spectrum at 266 nm have been observed and studied.

  5. Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

    NASA Astrophysics Data System (ADS)

    Binetti, Simona; Le Donne, Alessia; Rolfi, Andrea; Jäggi, Beat; Neuenschwander, Beat; Busto, Chiara; Frigeri, Cesare; Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio

    2016-05-01

    Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p-n junction.

  6. Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

    NASA Technical Reports Server (NTRS)

    Williams, A.; Seidel, D. J.; Maleki, J.

    1993-01-01

    A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.

  7. Arctic stratospheric ozone depletion and increased UVB radiation: potential impacts to human health.

    PubMed

    De Fabo, Edward C

    2005-12-01

    Contrary to popular belief, stratospheric ozone depletion, and the resultant increase in solar UV-B (280-320 nm), are unlikely to fully recover soon. Notwithstanding the success of the Montreal Protocol in reducing the amount of ozone destroying chemicals into the stratosphere, the life-times of these compounds are such that even with full compliance with the Protocol by all countries, it will be decades before stratospheric ozone could return to pre-1980 levels. This raises the question, therefore, of what will happen to biological processes essential to the maintenance of life on earth which are sensitive to damage by increased UV-B radiation, particularly those involved with human health? The polar regions, because of the vagaries of climate and weather, are the bellwether for stratospheric ozone depletion and will, therefore, be the first to experience impacts due to increases in solar UV-B radiation. The impacts of these are incompletely understood and cannot be predicted with certainty. While some UV-B impacts on human health are recognized, much is unknown, unclear and uncertain. Thus, this paper attempts, as a first approximation, to point out potential impacts to the health and welfare of human inhabitants of the Arctic due to increased solar UV-B radiation associated with stratospheric ozone depletion. As will be seen, much more data is critically needed before adequate risk assessment can occur. PMID:16440613

  8. Lack of photoprotection against UVB-induced erythema by immediate pigmentation induced by 382 nm radiation

    SciTech Connect

    Black, G.; Matzinger, E.; Gange, R.W.

    1985-11-01

    Immediate pigment darkening (IPD) was induced on the backs of 11 human volunteers of skin types III and IV by exposing the skin to UVA radiation (382 nm). The minimum erythema dose (MED) of UVB radiation was also determined by exposing sites to graduated doses of 304 nm radiation. The order of exposure of distinct anatomic areas was as follow: UVB followed by IPD induction; IPD induction followed by UVB; IPD induction followed 3 h later by UVB; and UVB only. Erythema responses induced by UVB were graded by inspection 24 h later and the MEDs in the 4 areas were compared. The induction of IPD before UVB exposure caused no significant change in the MED compared to sites receiving UVB only, or receiving UVA radiation after UVB, confirming that the IPD reaction does not protect against UVB-induced erythema. There was also no evidence of photorecovery, i.e., an increase in the MED of UVB resulting from exposure to longer wavelength, UV or visible radiation following UVB exposure.

  9. Photodecomposition of hexachlorobiphenyl by radiation of a KrCl (222 nm) barrier-discharge excilamp

    NASA Astrophysics Data System (ADS)

    Pikulev, A. A.; Tsvetkov, V. M.

    2010-01-01

    The process of dechlorination of 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) under the action of UV radiation of a KrCl* (222 nm) barrier-discharge excilamp has been studied. The photolysis was performed in PCB 153 solutions in hexane with concentrations of 10 μg/ml (sample 1) and 1 μg/ml (sample 2) and in a PCB 153 film on a silica plate (sample 3). The degree of PCB 153 decomposition was determined using the optical transmission spectra measured in a 185-350 nm wavelength range. An analysis of these spectra showed that chlorine atoms in ortho 2,2'-positions are detached first. At a UV radiation intensity of 3 mW/cm2 on the sample surface, the residual PCB 153 content in samples 1-3 was below 2% (60-min exposure), below 3% (25-min exposure), and below 20% (60-min exposure), respectively.

  10. Different oxidative stress response in keratinocytes and fibroblasts of reconstructed skin exposed to non extreme daily-ultraviolet radiation.

    PubMed

    Marionnet, Claire; Pierrard, Cécile; Lejeune, François; Sok, Juliette; Thomas, Marie; Bernerd, Françoise

    2010-01-01

    Experiments characterizing the biological effects of sun exposure have usually involved solar simulators. However, they addressed the worst case scenario i.e. zenithal sun, rarely found in common outdoor activities. A non-extreme ultraviolet radiation (UV) spectrum referred as "daily UV radiation" (DUVR) with a higher UVA (320-400 nm) to UVB (280-320 nm) irradiance ratio has therefore been defined. In this study, the biological impact of an acute exposure to low physiological doses of DUVR (corresponding to 10 and 20% of the dose received per day in Paris mid-April) on a 3 dimensional reconstructed skin model, was analysed. In such conditions, epidermal and dermal morphological alterations could only be detected after the highest dose of DUVR. We then focused on oxidative stress response induced by DUVR, by analyzing the modulation of mRNA level of 24 markers in parallel in fibroblasts and keratinocytes. DUVR significantly modulated mRNA levels of these markers in both cell types. A cell type differential response was noticed: it was faster in fibroblasts, with a majority of inductions and high levels of modulation in contrast to keratinocyte response. Our results thus revealed a higher sensitivity in response to oxidative stress of dermal fibroblasts although located deeper in the skin, giving new insights into the skin biological events occurring in everyday UV exposure. PMID:20706594

  11. New apparatus with high radiation energy between 320-460 nm: physical description and dermatological applications

    SciTech Connect

    Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

    1981-01-01

    A new apparatus (UVASUN 5000) is presented with high-radiation energy between 320 to 460 nm. The measureable energy below 320 nm was shown to be many orders of magnitude too low to produce erythema. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. At a skin-target distance of 0.2 m the size of the irradiated area is 0.35 x 0.35 m, and the measured mean uv-A intensity is about 1400 W. m-2 (140 mW . cm-2). The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-a applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. The calculated IPD threshold time was 1.8 min at 0.2 m. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. The instrument was also successfully used for photo-patch testing and reproduction of skin lesions of polymorphous light eruption. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.

  12. A cesium bromide photocathode excited by 405 nm radiation

    SciTech Connect

    Maldonado, J. R.; Cheng, Y. T.; Pease, Fabian W.; Hesselink, L.; Pianetta, P.

    2014-07-14

    In several applications, such as electron beam lithography and X-ray differential phase contrast imaging, there is a need for a free electron source with a current density at least 10 A/cm{sup 2} yet can be shaped with a resolution down to 20 nm and pulsed. Additional requirements are that the source must operate in a practical demountable vacuum (>1e-9 Torr) and be reasonably compact. In prior work, a photocathode comprising a film of CsBr on metal film on a sapphire substrate met the requirements except it was bulky because it required a beam (>10 W/cm{sup 2}) of 257 nm radiation. Here, we describe an approach using a 405 nm laser which is far less bulky. The 405 nm laser, however, is not energetic enough to create color centers in CsBr films. The key to our approach is to bombard the CsBr film with a flood beam of about 1 keV electrons prior to operation. Photoelectron efficiencies in the range of 100–1000 nA/mW were demonstrated with lifetimes exceeding 50 h between electron bombardments. We suspect that the electron bombardment creates intraband color centers whence electrons can be excited by the 405 nm photons into the conduction band and thence into the vacuum.

  13. Radiative transfer modeling of the OI 135.6 nm emission in the nighttime ionosphere

    NASA Astrophysics Data System (ADS)

    Qin, Jianqi; Makela, Jonathan J.; Kamalabadi, Farzad; Meier, R. R.

    2015-11-01

    Remote sensing of the nighttime OI 135.6 nm emissions has been a widely used method for measuring the F region ionospheric plasma densities. In this work, we first develop a comprehensive radiative transfer model from first principles to investigate the effects of different physical processes on the production and transport of the 135.6 nm photons in the ionosphere and then propose a new approach for estimating electron densities from the nightglow. The forward modeling investigation indicates that under certain conditions mutual neutralization can contribute up to ˜38% of the total production of the nighttime 135.6 nm emissions. Moreover, depending on the ionospheric conditions, resonant scattering by atomic oxygen and pure absorption by oxygen molecules can reduce the limb brightness observed by satellite-borne instruments by up to ˜40% while enhancing the brightness viewing in the nadir direction by typically ˜25%. Further analysis shows that without properly addressing these effects in the inversion process, the peak electron density in the F region (NmF2) obtained using limb observations can be overestimated by up to ˜24%. For accurate estimation of the ionospheric electron density, we develop a new type of inverse model that accounts for the effects of mutual neutralization, resonant scattering, and pure absorption. This inversion method requires the knowledge of O and O2 densities in order to solve the radiative transfer equations. Application of the inverse model to the nighttime ionosphere in the noiseless cases demonstrates that the electron density can be accurately quantified with only ˜1% error in NmF2 and hmF2.

  14. Kinetics of avoidance of simulated solar uv radiation by two arthropods

    SciTech Connect

    Barcelo, J.A.; Calkins, J.

    1980-12-01

    There is an increasing likelihood that the solar uv-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar uv-B to withstand full summer sunlight and thus mechanisms which facilitate avoidance of solar uv-B exposure may have significance for the survival of sensitive species. There are many alternative pathways which would lead to avoidance of solar uv-B. We have investigated the dynamics of biological reactions to simulated solar uv-B radiation in two small arthropods, the two-spotted spider mite Tetranychus urticae Koch and the aquatic copepod Cyclops serrulatus. Observations of positioning and rate of movement were made; a mathematical formalism was developed which assisted in interpretation of the observations. Our observations suggest that, although avoidance would mitigate increased solar uv-B effects, even organisms which specifically reduce their uv-B exposure would encounter additional stress if ozone depletion does occur.

  15. Response of Two Legumes to Two Ultraviolet-B Radiation Regimes

    NASA Technical Reports Server (NTRS)

    Levy, Daniel L.; Skiles, J. W.

    2000-01-01

    Depletion of the stratospheric ozone layer has been directly linked to increased levels of UV radiation at the earth's surface. The purpose of this study was to evaluate the responses of soybean (Glycine max) and alfalfa (Medicago sativa) to increased UV-B radiation (280-320 nm). Soybean and alfalfa were grown successively in a growth chamber that provided UV-B intensities 45% above nominal summer field levels. Mylar-D (UVB opaque) and mono-acetate (UV-B transparent) films were used to establish the two UV-B treatments. Soybean grown under increased UV showed 21% smaller internodal lengths and higher concentrations of UV-B absorbing pigments (i.e. flavonoids) compared to plants grown under no UV. Significant results for alfalfa included 22% greater leaf flavonoid concentration under increased UV, 14% greater leaf chlorophyll concentration under no UV, and 32% greater above-ground biomass with no UV. These leguminous species possess mechanisms that protect against UV-B damage as indicated by increases in foliar concentrations of UV-B absorbing compounds. Alfalfa appears to be more sensitive to UV-B damage than soybean. Remote sensing of chlorophyll fluorescence may offer a means of monitoring UV-induced plant stress and damage.

  16. Effects of solar radiation on manganese oxide reactions with selected organic compounds

    SciTech Connect

    Bertino, D.J.; Zepp, R.G. )

    1991-07-01

    The effects of sunlight on aqueous redox reactions between manganese oxides (MnO{sub x}) and selected organic substances are reported. No sunlight-induced rate enhancement was observed for the MnO{sub x} oxidation of substituted phenols, anisole, o-dichlorobenzene, or p-chloroaniline. On the other hand, solar radiation did accelerate the reduction of manganese oxides by dissolved organic matter (DOM) from aquatic environments. The photoreduction of MnO{sub x} by DOM was little affected by molecular oxygen in air-saturated water (250 {mu}M), but was inhibited by 2,6-dichloroindophenol (0.5-6 {mu}M), and excellent electron acceptor. MnO{sub x} reduction also was photosensitized by anthraquinone-2-sulfonate. These results indicate that the photoreduction probably involves electron transfer from excited states of sorbed DOM to the oxide surface. Wavelength studies indicated that ultraviolet-B radiation (280-320 nm) plays an important role in this photoreduction.

  17. Lanthanum (III) regulates the nitrogen assimilation in soybean seedlings under ultraviolet-B radiation.

    PubMed

    Huang, Guangrong; Wang, Lihong; Zhou, Qing

    2013-01-01

    Ultraviolet-B (UV-B, 280-320 nm) radiation has seriously affected the growth of plants. Finding the technology/method to alleviate the damage of UV-B radiation has become a frontal topic in the field of environmental science. The pretreatment with rare earth elements (REEs) is an effective method, but the regulation mechanism of REEs is unknown. Here, the regulation effects of lanthanum (La(III)) on nitrogen assimilation in soybean seedlings (Glycine max L.) under ultraviolet-B radiation were investigated to elucidate the regulation mechanism of REEs on plants under UV-B radiation. UV-B radiation led to the inhibition in the activities of the key enzymes (nitrate reductase, glutamine synthetase, glutamate synthase) in the nitrogen assimilation, the decrease in the contents of nitrate and soluble proteins, as well as the increase in the content of amino acid in soybean seedlings. The change degree of UV-B radiation at the high level (0.45 W m(-2)) was higher than that of UV-B radiation at the low level (0.15 W m(-2)). The pretreatment with 20 mg L(-1) La(III) could alleviate the effects of UV-B radiation on the activities of nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase, promoting amino acid conversion and protein synthesis in soybean seedlings. The regulation effect of La(III) under UV-B radiation at the low level was better than that of UV-B radiation at the high level. The results indicated that the pretreatment with 20 mg L(-1) La(III) could alleviate the inhibition of UV-B radiation on nitrogen assimilation in soybean seedlings. PMID:23090712

  18. Core level photoionization on free sub-10-nm nanoparticles using synchrotron radiation

    SciTech Connect

    Meinen, Jan; Leisner, Thomas; Khasminskaya, Svetlana; Eritt, Markus; Antonsson, Egill; Langer, Burkhard; Ruehl, Eckart

    2010-08-15

    A novel instrument is presented, which permits studies on singly charged free nanoparticles in the diameter range from 1 to 30 nm using synchrotron radiation in the soft x-ray regime. It consists of a high pressure nanoparticle source, a high efficiency nanoparticle beam inlet, and an electron time-of-flight spectrometer suitable for probing surface and bulk properties of free, levitated nanoparticles. We show results from x-ray photoelectron spectroscopy study near the Si L{sub 3,2}-edge on 8.2 nm SiO{sub 2} particles prepared in a nanoparticle beam. The possible use of this apparatus regarding chemical reactions on the surface of nanometer-sized particles is highlighted. This approach has the potential to be exploited for process studies on heterogeneous atmospheric chemistry.

  19. Experimental investigation of gamma ray radiation effects on 1550nm single mode fiber

    NASA Astrophysics Data System (ADS)

    Liu, Qingfeng; Ma, Jing; Tan, Liying; Zhou, Yanping; Che, Chi; Yang, Qingbo

    2015-03-01

    We compared the degradation of two kinds of 1550nm single-mode optical fibers following the irradiation by gamma ray (60Co). Over a total dose of 9.06×104 rad, the absorption coefficient increased while the rates were different between samples. The influence of ionizing radiation is theoretically analyzed. In room temperature annealing experiment, the absorption coefficient of Corning sample was recovered visibly, but Alcatel sample continues to deteriorate. It is suggested that different producing technology and doping are clearly influence the generation and recombination process of color center.

  20. Time-resolved spectroscopy of nucleic acid systems using synchrotron radiation from 230 nm to 354 nm

    NASA Astrophysics Data System (ADS)

    Daniels, Malcolm; Ballini, Jean-Pierre; Vigny, Paul

    1992-07-01

    The excited states of nucleic acids are complex, both at the individual chromophore level and because of the effect of stacking interactions on the electronic states. Considerable progress has been made recently by studying the lifetimes of the stacked states and by utilizing the technique of time-resolved spectroscopy. Experimental results obtained using the ACO synchrotron at LURE, Orsay, will be presented. Resolution of the decay data gives a model-based estimate of the number of emitting species and their lifetimes, and this information is then used to deconvolate experimental time-windowed spectra (time-delayed spectra) to give true time-resolved spectra. It is a unique feature of the synchrotron, compared with the laser, that the combination of delayed detection (photon counting) with the continuous wavelength distribution of the synchrotron allows the acquisition of excitation spectra by uninterrupted repetitive scanning over a wide range of UV exciting wavelengths, in the present work from 230 nm to 354 nm. Such time-delayed excitation spectra can also be deconvoluted into components corresponding to the various time-resolved emission spectra. In this way we are able to demonstrate for the first time that ground state stacking interactions are directly responsible for excimer-like emissions. Time-resolved emission spectra and time-resolved excitation spectra will be presented for the dinucleoside phosphate d(CG) and the synthetic alternating polynucleotide poly d(GC), a `B-type' DNA structure.

  1. Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

    NASA Technical Reports Server (NTRS)

    Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

    1996-01-01

    The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

  2. First Operation of a Free-Electron Laser Generating GW Power Radiation at 32-Nm Wavelength

    SciTech Connect

    Ayvazian, V.; Baboi, N.; Bahr, J.; Balandin, V.; Beutner, B.; Brandt, A.; Bohnet, I.; Bolzmann, A.; Brinkmann, R.; Brovko, O.I.; Carneiro, J.P.; Casalbuoni, S.; Castellano, M.; Castro, P.; Catani, L.; Chiadroni, E.; Choroba, S.; Cianchi, A.; Delsim-Hashemi, H.; Di Pirro, G.; Dohlus, M.; /Saclay /Wurzburg U. /BESSY, Berlin /CANDLE, Yerevan /Darmstadt, Tech. Hochsch. /DESY /DESY, Zeuthen /Fermilab /Hamburg U. /INFM, Padua /Frascati /INFN, Milan /INFN, Rome2 /Sofiya, Inst. Nucl. Res. /Dubna, JINR /Orsay, LAL /Max Born Inst., Berlin /SLAC

    2006-09-15

    Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL). Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important milestone towards a user facility designed for wavelengths down to 6 nm. With a peak brilliance exceeding the state-of-the-art of synchrotron radiation sources by seven orders of magnitude, this device opens a new field of experiments, and it paves the way towards sources with even shorter wavelengths, such as the Linac Coherent Light Source at Stanford, USA, and the European X-ray Free Electron Laser Facility in Hamburg, Germany.

  3. First operation of a free-electron laser generating GW power radiation at 32 nm wavelength

    NASA Astrophysics Data System (ADS)

    Ayvazyan, V.; Baboi, N.; Bähr, J.; Balandin, V.; Beutner, B.; Brandt, A.; Bohnet, I.; Bolzmann, A.; Brinkmann, R.; Brovko, O. I.; Carneiro, J. P.; Casalbuoni, S.; Castellano, M.; Castro, P.; Catani, L.; Chiadroni, E.; Choroba, S.; Cianchi, A.; Delsim-Hashemi, H.; di Pirro, G.; Dohlus, M.; Düsterer, S.; Edwards, H. T.; Faatz, B.; Fateev, A. A.; Feldhaus, J.; Flöttmann, K.; Frisch, J.; Fröhlich, L.; Garvey, T.; Gensch, U.; Golubeva, N.; Grabosch, H.-J.; Grigoryan, B.; Grimm, O.; Hahn, U.; Han, J. H.; Hartrott, M. V.; Honkavaara, K.; Hüning, M.; Ischebeck, R.; Jaeschke, E.; Jablonka, M.; Kammering, R.; Katalev, V.; Keitel, B.; Khodyachykh, S.; Kim, Y.; Kocharyan, V.; Körfer, M.; Kollewe, M.; Kostin, D.; Krämer, D.; Krassilnikov, M.; Kube, G.; Lilje, L.; Limberg, T.; Lipka, D.; Löhl, F.; Luong, M.; Magne, C.; Menzel, J.; Michelato, P.; Miltchev, V.; Minty, M.; Möller, W. D.; Monaco, L.; Müller, W.; Nagl, M.; Napoly, O.; Nicolosi, P.; Nölle, D.; Nuñez, T.; Oppelt, A.; Pagani, C.; Paparella, R.; Petersen, B.; Petrosyan, B.; Pflüger, J.; Piot, P.; Plönjes, E.; Poletto, L.; Proch, D.; Pugachov, D.; Rehlich, K.; Richter, D.; Riemann, S.; Ross, M.; Rossbach, J.; Sachwitz, M.; Saldin, E. L.; Sandner, W.; Schlarb, H.; Schmidt, B.; Schmitz, M.; Schmüser, P.; Schneider, J. R.; Schneidmiller, E. A.; Schreiber, H.-J.; Schreiber, S.; Shabunov, A. V.; Sertore, D.; Setzer, S.; Simrock, S.; Sombrowski, E.; Staykov, L.; Steffen, B.; Stephan, F.; Stulle, F.; Sytchev, K. P.; Thom, H.; Tiedtke, K.; Tischer, M.; Treusch, R.; Trines, D.; Tsakov, I.; Vardanyan, A.; Wanzenberg, R.; Weiland, T.; Weise, H.; Wendt, M.; Will, I.; Winter, A.; Wittenburg, K.; Yurkov, M. V.; Zagorodnov, I.; Zambolin, P.; Zapfe, K.

    2006-02-01

    Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range [1-4]. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL) [5-10]. Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important milestone towards a user facility designed for wavelengths down to 6 nm. With a peak brilliance exceeding the state-of-the-art of synchrotron radiation sources [4] by seven orders of magnitude, this device opens a new field of experiments, and it paves the way towards sources with even shorter wavelengths, such as the Linac Coherent Light Source [3] at Stanford, USA, and the European X-ray Free Electron Laser Facility [4] in Hamburg, Germany.

  4. Cavity-enhanced frequency doubling from 795nm to 397.5nm ultra-violet coherent radiation with PPKTP crystals in the low pump power regime.

    PubMed

    Wen, Xin; Han, Yashuai; Bai, Jiandong; He, Jun; Wang, Yanhua; Yang, Baodong; Wang, Junmin

    2014-12-29

    We demonstrate a simple, compact and cost-efficient diode laser pumped frequency doubling system at 795 nm in the low power regime. In two configurations, a bow-tie four-mirror ring enhancement cavity with a PPKTP crystal inside and a semi-monolithic PPKTP enhancement cavity, we obtain 397.5nm ultra-violet coherent radiation of 35mW and 47mW respectively with a mode-matched fundamental power of about 110mW, corresponding to a conversion efficiency of 32% and 41%. The low loss semi-monolithic cavity leads to the better results. The constructed ultra-violet coherent radiation has good power stability and beam quality, and the system has huge potential in quantum optics and cold atom physics. PMID:25607194

  5. Sunlight suppressing rejection of 280- to 320-nm UV-radiation-induced skin tumors in mice

    SciTech Connect

    Morison, W.L.; Kelley, S.P.

    1985-02-01

    Repeated exposure of female C3H/HeNCR- mice to sunlight prevented the normal immunologic rejection of a UV-induced tumor. This systemic immunologic alteration was transferred to syngeneic lethally X-irradiated animals with lymphoid cells from mice exposed to sunlight. The lymphoid cells also were able to suppress the capacity of lymphoid cells from normal animals to reject a UV-induced tumor. The 295- to 320-nm wave band appeared to be responsible for this immunosuppressive effect of sunlight because suppression was prevented by filtration of the radiation through Mylar and by application of a sunscreen containing para-aminobenzoic acid. These observations may have importance in understanding the pathogenesis of sunlight-induced skin cancer in humans.

  6. Absorption of 308-nm excimer laser radiation by balanced salt solution, sodium hyaluronate, and human cadaver eyes

    SciTech Connect

    Keates, R.H.; Bloom, R.T.; Schneider, R.T.; Ren, Q.; Sohl, J.; Viscardi, J.J. )

    1990-11-01

    Absorption of the excimer laser radiations of 193-nm argon fluorine and 308-nm xenon chloride in balanced salt solution, sodium hyaluronate, and human cadaver eyes was measured. The absorption of these materials as considerably different for the two wavelengths; we found that 308-nm light experienced much less absorption than the 193-nm light. The extinction coefficient (k) for 308 nm was k = 0.19/cm for balanced salt solution and k = 0.22/cm for sodium hyaluronate. In contrast to this, the extinction coefficient for 193 nm was k = 140/cm for balanced salt solution and k = 540/cm for sodium hyaluronate. Two 1-day-old human phakic cadaver eyes showed complete absorption with both wavelengths. Using aphakic eyes, incomplete absorption was noted at the posterior pole with 308 nm and complete absorption was noted with 193 nm. The extinction in the anterior part of aphakic eyes (the first 6 mm) was 4.2/cm for 308 nm, meaning that the intensity of the light is reduced by a factor of 10 after traveling the first 5.5 mm. However, we observed that the material in the eye fluoresces, meaning the 308 nm is transformed into other (longer) wavelengths that travel through the total eye with minimal absorption. Conclusions drawn from this experiment are that the use of the 308-nm wavelength may have undesirable side effects, while the use of the 193-nm wavelength should be consistent with ophthalmic use on both the cornea and the lens.

  7. Animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation

    SciTech Connect

    Chew, S.; DeLeo, V.A.; Harber, L.C.

    1987-10-01

    Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of (/sup 3/H)thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by (/sup 3/H)thymidine incorporation.

  8. Precision drilling of fused silica with 157-nm excimer laser radiation

    NASA Astrophysics Data System (ADS)

    Temme, Thorsten; Ostendorf, Andreas; Kulik, Christian; Meyer, Klaus

    2003-07-01

    μFor drilling fused silica, mechanical techniques like with diamond drills, ultrasonic machining, sand blasting or water jet machining are used. Also chemical techniques like laser assisted wet etching or thermal drilling with CO2-lasers are established. As an extension of these technologies, the drilling of micro-holes in fused silica with VUV laser radiation is presented here. The high absorption of the 157 nm radiation emitted by the F2 excimer laser and the short pulse duration lead to a material ablation with minimised impact on the surrounding material. Contrary to CO2-laser drilling, a molten and solidified phase around the bore can thus be avoided. The high photon energy of 7.9 eV requires either high purity nitrogen flushing or operation in vacuum, which also effects the processing results. Depending on the required precision, the laser can be used for percussion drilling as well as for excimer laser trepanning, by applying rotating masks. Rotating masks are especially used for high aspect ratio drilling with well defined edges and minimised debris. The technology is suitable particularly for holes with a diameter below 200 μm down to some microns in substrates with less than 200 μm thickness, that can not be achieved with mechanical methods. Drilling times in 200 μm fused silica substrates are in the range of ten seconds, which is sufficient to compete with conventional methods while providing similar or even better accuracy.

  9. Generation of Terahertz Radiation from Fe-doped InGaAsP Using 800 nm to 1550 nm Pulsed Laser Excitation

    NASA Astrophysics Data System (ADS)

    Hatem, O.; Freeman, J. R.; Cunningham, J. E.; Cannard, P. J.; Robertson, M. J.; Linfield, E. H.; Davies, A. G.; Moodie, D. G.

    2016-05-01

    We demonstrate efficient generation of terahertz (THz) frequency radiation by pulsed excitation, at wavelengths between 800 and 1550 nm, of photoconductive (PC) switches fabricated using Fe-doped InGaAsP wafers, grown by metal organic chemical vapor deposition (MOCVD). Compared to our previous studies of Fe-doped InGaAs wafers, Fe:InGaAsP wafers exhibited five times greater dark resistivity to give a value of 10 kΩ cm, and Fe:InGaAsP PC switches produced five times higher THz power emission. The effect of Fe-doping concentration (between 1E16 and 1.5E17 cm-3) on optical light absorption (between 800 and 1600 nm), on resistivity, and on THz emission is also discussed.

  10. SENSITIVITY OF ANTARCTIC UROSPORA PENICILLIFORMIS (ULOTRICHALES, CHLOROPHYTA) TO ULTRAVIOLET RADIATION IS LIFE-STAGE DEPENDENT(1).

    PubMed

    Roleda, Michael Y; Campana, Gabriela L; Wiencke, Christian; Hanelt, Dieter; Quartino, Maria Liliana; Wulff, Angela

    2009-06-01

    The sensitivity of different life stages of the eulittoral green alga Urospora penicilliformis (Roth) Aresch. to ultraviolet radiation (UVR) was examined in the laboratory. Gametophytic filaments and propagules (zoospores and gametes) released from filaments were separately exposed to different fluence of radiation treatments consisting of PAR (P = 400-700 nm), PAR + ultraviolet A (UVA) (PA, UVA = 320-400 nm), and PAR + UVA + ultraviolet B (UVB) (PAB, UVB = 280-320nm). Photophysiological indices (ETRmax , Ek , and α) derived from rapid light curves were measured in controls, while photosynthetic efficiency and amount of DNA lesions in terms of cyclobutane pyrimidine dimers (CPDs) were measured after exposure to radiation treatments and after recovery in low PAR; pigments of propagules were quantified after exposure treatment only. The photosynthetic conversion efficiency (α) and photosynthetic capacity (rETRmax ) were higher in gametophytes compared with the propagules. The propagules were slightly more sensitive to UVB-induced DNA damage; however, both life stages of the eulittoral inhabiting turf alga were not severely affected by the negative impacts of UVR. Exposure to a maximum of 8 h UVR caused mild effects on the photochemical efficiency of PSII and induced minimal DNA lesions in both the gametophytes and propagules. Pigment concentrations were not significantly different between PAR-exposed and PAR + UVR-exposed propagules. Our data showed that U. penicilliformis from the Antarctic is rather insensitive to the applied UVR. This amphi-equatorial species possesses different protective mechanisms that can cope with high UVR in cold-temperate waters of both hemispheres and in polar regions under conditions of increasing UVR as a consequence of further reduction of stratospheric ozone. PMID:27034036

  11. Studies on the mechanism of systemic suppression of contact hypersensitivity by UVB radiation. II. Differences in the suppression of delayed and contact hypersensitivity in mice.

    PubMed

    Kripke, M L; Morison, W L

    1986-05-01

    Exposing mice to UV radiation in the UVB range (280-320 nm) causes a selective immune suppression that contributes to the development of UVB-induced skin cancers. Among the immune responses suppressed by UVB irradiation are contact and delayed hypersensitivity reactions to haptens administered at unexposed sites. In these studies we provide evidence that delayed and contact hypersensitivity to the same hapten are not equivalent reactions and that they are suppressed in UVB-irradiated mice by 2 different mechanisms. This conclusion is based on the findings that: suppression of contact hypersensitivity could not be overcome by immunizing UVB-irradiated mice with hapten-coupled antigen-presenting cells derived from normal donors; and treatment of UVB-irradiated mice with methylprednisolone before immunization prevented the suppression of delayed hypersensitivity but had no effect on the suppression of contact hypersensitivity. The decreased ability to induce contact hypersensitivity in UVB-irradiated mice could be transferred to x-irradiated mice by reconstituting them with spleen cells from UVB-irradiated donors. The induction of hapten-specific suppressor cells, however, required both UVB irradiation and priming with hapten. Based on these results, we postulate that UVB irradiation induces a population of suppressor-inducer cells with specificity for a modified skin antigen and that this antigen serves as a carrier molecule for haptens that induce contact hypersensitivity and for tumor-specific transplantation antigens on UVB-induced tumors. PMID:3745963

  12. The influence of ultraviolet-B radiation on growth, hydroxycinnamic acids and flavonoids of Deschampsia antarctica during Springtime ozone depletion in Antarctica.

    PubMed

    Ruhland, Christopher T; Xiong, Fusheng S; Clark, W Dennis; Day, Thomas A

    2005-01-01

    We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the growth, biomass production and phenylpropanoid concentrations of Deschampsia antarctica during the springtime ozone depletion season at Palmer Station, along the Antarctic Peninsula. Treatments involved placing filters on frames over potted plants that reduced levels of biologically effective UV-B either by 83% (reduced UV-B) or by 12% (near-ambient UV-B) over the 63 day experiment (7 November 1998-8 January 1999) when ozone depletion averaged 17%. Plants growing under near-ambient UV-B had 41% and 40% lower relative growth rates and net assimilation rates, respectively, than those under reduced UV-B. The former plants produced 50% less total biomass as a result of having 47% less aboveground biomass. The reduction in aboveground biomass was a result of a 29% lower leaf elongation rate resulting in shorter leaves and 59% less total leaf area in plants grown under reduced UV-B. p-Coumaric, caffeic and ferulic acids were the major hydroxycinnamic acids, and luteolin derivatives were the major flavonoids in both insoluble and soluble leaf extracts. Concentrations of insoluble p-coumaric and caffeic acid and soluble ferulic acids were 38%, 48% and 60% higher, respectively, under near-ambient UV-B than under reduced UV-B. There were no UV-B effects on concentrations of insoluble or soluble flavonoids. PMID:15689180

  13. Researchers lack data on trends in UV radiation at Earth's surface

    SciTech Connect

    Zurer, P.S.

    1993-07-26

    Current anxiety about depletion of stratospheric ozone stems from the expected resulting increase in biologically damaging ultraviolet (UV) radiation at Earth's surface. Atmospheric ozone absorbs sunlight with wavelengths shorter than 320 nm--the highest-energy UV-B wavelengths (280-320 nm) that can damage DNA in living systems. But surprisingly, despite firm evidence the ozone layer is being eroded by chlorine and bromine from man-made compounds, very little information exists on how UV light intensity is changing. Solid data from Antarctica reveal that UV radiation soars under the ozone hole, where fully half of the atmospheric ozone is destroyed each spring. But elsewhere on the globe, where ozone has been thinning at a rate of a few percent per decade, the corresponding trends in UV intensity are not at all clear. In the late 1970s and early 1980s the problem of ozone depletion seemed solved. The US had banned the use of chlorofluorocarbons (CFCs) in aerosols. Model calculations were predicting CFCs would cause only a small loss of ozone by the second half of the 21st century. Costly monitoring of UV radiation commanded little attention. Attitudes began to change with the 1985 discovery of the Antarctic ozone hole. The National Science Foundation (NSF) established UV monitoring stations in the Antarctic in 1988, adding an Alaskan station in 1990. Both the Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have programs in the works that will eventually place monitoring stations across the US, but it will be many years before researchers have access to the kind of extensive database necessary to reliably evaluation long-term trends in UV intensity.

  14. [The effect of solar ultraviolet radiation (UVR) on induction of skin cancers].

    PubMed

    Pacholczyk, Marta; Czernicki, Jan; Ferenc, Tomasz

    2016-01-01

    Ultraviolet radiation is a physical mutagenic and cancerogenic factor. About 95% of ultraviolet A (UVA) (320-400 nm) and 5% of UVB (280-320 nm) reach the Earth's surface. Melanin is a natural skin protective factor against UV radiation. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH) cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1) mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R). Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2) plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β and IL-6). Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A), cyclin-dependent kinase 4 (CDK4), Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and proto-oncogene B-Raf (BRAF). The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2):255-266. PMID:27221301

  15. SCIATRAN 2.0 - A new radiative transfer model for geophysical applications in the 175 - 2400 nm spectral region.

    NASA Astrophysics Data System (ADS)

    Rozanov, A.; Rozanov, V.; Buchwitz, M.; Kokhanovsky, A.; Burrows, J. P.

    The SCIATRAN radiative transfer models (RTMs) are next generation RTMs based on the well-known GOMETRAN model which was originally developed to simulate solar radiation backscattered from the atmosphere and reflected from the Earth's surface in the spectral range 240--800 nm as measured by the Global Ozone Monitoring Experiment (GOME) in nadir viewing geometry. A successor RTM called SCIATRAN was extended to cover the spectral range 240--2380 nm comprising the 8 spectral channels of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument. SCIATRAN versions up to 1.2 utilize the pseudo-spherical approach, including refraction, appropriate for solar zenith angles up to about 92° and near-nadir viewing angles. A new generation of the SCIATRAN radiative transfer model (version 2.0) comprises all features of the latest SCIATRAN 1.2 RTM supporting additionally radiative transfer calculations in a spherical atmosphere. The program is written in FORTRAN 95 and suitable for parallel execution using the OMP-standard. The wavelength range covered by the radiative transfer model is extended to 175 nm including Schuman-Runge and Herzberg absorption bands. The SCIATRAN 2.0 model exhibits the following new capabilities : (i) modeling of the scattered solar radiation in limb viewing geometry as well as any kind of measurements of the scattered radiation within the atmosphere, (ii) corresponding quasi-analytical calculation of weighting functions of atmospheric parameters, (iii) airmass factor calculations for ground-based, space- and airborne measurements including off-axis geometry, (iv) accounting for photochemically active species, i.e., radiative transfer calculations can be performed using solar zenith angle dependent vertical distributions of atmospheric trace gases, (v) height resolved radiation fluxes, including actinic fluxes for photolysis rate calculations, (vi) inelastic rotational Raman scattering in any supported viewing

  16. Non-coherent visible and infrared radiation increase survival to UV (254 nm) in Escherichia coli K12.

    PubMed

    Lage, C; Teixeira, P C; Leitão, A C

    2000-02-01

    Interactions between visible or infrared (IR) and ultraviolet (UV, 254 nm) radiation have been studied in E. coli. Pre-illumination with non-coherent monochromatic 446, 466, 570 and 685 nm radiation, as well as with polychromatic red and IR radiation at room temperature, leads to increased cell survival after a subsequent irradiation with UV light. In the thermic range of the spectrum (red and IR), IR but not red light pre-treatment is able to increase cell survival to a subsequent lethal heat (51 degrees C) challenge, suggesting that increased UV survival may be due to IR-induced heat-shock response. On the other hand, visible-light-induced resistance may be due to a different mechanism, possibly involved with unknown bacterial light receptors. PMID:10836546

  17. Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities

    SciTech Connect

    Schofield, O.; Prezelin, B.B.; Kroon, B.M.A.

    1995-10-01

    One goal of the Icecolors 1993 study was to determine whether or not photosystem II (PSII) was a major target site for photoinhibition by ultraviolet-B radiation (Q{sub UVB}, 280-320 nm) in natural communities. Second, the degree to which Q{sub UVB} inhibition of PSII could account for Q{sub UVB} effects on whole cell rates of carbon fixation in phytoplankton was assessed. On 1 October, 1993, at Palmer Station (Antarctica), dense samples of a frazil ice algal community were collected and maintained outdoors in the presence or absence of Q{sub UVB} and/or ultraviolet-A (Q{sub UVA}, 320-400 nm) radiation. The time of day course of UV inhibition of primary production was tracted. Over the day, {phi}{sub IIe}{degrees} declined due to increasing time-integrated dose exposure of Q{sub UVB}. The Q{sub UVB}-driven inhibition of {phi}{sub IIe}{degrees} increased from 4% in the early morning hours to a maximum of 23% at the end of the day. The Q{sub UVB} photoinhibition of PSII quantum yield did not recover by 6 h after sunset. In contrast, photoinhibition by Q{sub UVA} and photosynthetically available radiation (Q{sub PAR}, 400-700 nm) recovered during the late afternoon. Fluorescence-based estimates of carbon fixation rates were linearly correlated with measured carbon fixation. Fluorescence overestimated the observed Q{sub UVB} inhibition in measured carbon fixation rates. Researchers should be cautious in using fluorescence measurements to infer ultraviolet inhibition for rates of carbon fixation until there is a greater understanding of the coupling of carbon metabolism to PSII activity for natural populations. Despite these current limitations, fluorescence-based technologies represent powerful tools for studying the impact of the ozone hole on natural populations on spatial/temporal scales not possible using conventional productivity techniques. 55 refs., 11 figs., 2 tabs.

  18. Effects of ultraviolet-B radiation on fungal disease development in Cucumis sativus

    SciTech Connect

    Orth, A.B.; Teramura, A.H.; Sisler, H.D. )

    1990-09-01

    Stratospheric ozone depletion due to increased atmospheric pollutants has received considerable attention because of the potential increase in ultraviolet-B (UV-B, 280-320 nm) radiation that will reach the earth's surface. Three cucumber (Cucumis sativus L.) cultivars were exposed to a daily dose of 11.6 kJ m{sup {minus}2} biologically effective ultraviolet-B (UV-B{sub BE}) radiation in an unshaded greenhouse before and/or after injection by Colletotrichum lagenarium (Pass.) Ell. and Halst. or Cladosporium cucumerinum Ell. and Arth. and analyzed for disease development. Two of these cultivars, Poinsette and Calypso Hybrid, were disease resistant, while the third cultivar, Straight-8, was disease susceptible. Preinfectional treatment of 1 to 7 days with UV-B{sub BE} in Straight-8 led to greater severity of both diseases. Postinfectional UV treatment did not lead to increased disease severity caused by C. lagenarium, while preinfectional UV treatment in both Straight-8 and Poinsette substantially increased disease severity. Although resistant cultivars Poinsette and Calypso Hybrid showed increased anthracnose disease severity when exposed to UV-B, this effect was apparent only on the cotyledons. Both higher spore concentration and exposure to UV-B radiation resulted in greater disease severity. Of the cucumber cultivars tested for UV-B sensitivity, growth in Poinsette was most sensitive and Calypso Hybrid was least sensitive. These preliminary results indicate that the effects of UV-B radiation on disease development in cucumber vary depending on cultivar, timing and duration of UV-B exposure, inoculation level, and plant age.

  19. Broadband white radiation in Yb3+- and Er3+-doped nanocrystalline powders of yttrium orthophosphates irradiated by 972-nm laser radiation

    NASA Astrophysics Data System (ADS)

    Khrushchalina, S. A.; Ryabochkina, P. A.; Kyashkin, V. M.; Vanetsev, A. S.; Gaitko, O. M.; Tabachkova, N. Yu.

    2016-03-01

    The up-conversion luminescence of Er3+ from the 2 H 11/2, 4 S 3/2, and 4 F 9/2 levels in nanocrystals of Y0.95(1‒ x)Yb0.95 x Er0.05PO4 ( x = 0, 0.3, 0.5, 0.7, 1) orthophosphates activated with Er3+ ions has been studied under the excitation of Yb3+ ions to the 2 F 5/2 level by 972-nm cw laser radiation. Broadband radiation in the wavelength range of 370-900 nm has been observed at certain power densities of exciting laser radiation; this broadband radiation is absent in the case of excitation of the powders under study by pulsed laser radiation with a wavelength of 972 nm at a pulse repetition frequency of 10 Hz and a duration of a pulse of 15 ns. Experimental data indicating that this radiation is thermal in nature have been presented.

  20. Radiation Performance of 1 Gbit DDR SDRAMs Fabricated in the 90 nm CMOS Technology Node

    NASA Technical Reports Server (NTRS)

    Ladbury, Raymond L.; Gorelick, Jerry L.; Berg, M. D.; Kim, H.; LaBel, K.; Friendlich, M.; Koga, R.; George, J.; Crain, S.; Yu, P.; Reed, R. A.

    2006-01-01

    We present Single Event Effect (SEE) and Total Ionizing Dose (TID) data for 1 Gbit DDR SDRAMs (90 nm CMOS technology) as well as comparing this data with earlier technology nodes from the same manufacturer.

  1. On Sensitivity of Spectral Radiative Fluxes to Atmospheric Water Vapor in the 940 nm Region (Numerical Simulation)

    SciTech Connect

    Zhuravleva, T.B.; Firsov, K.M.

    2005-03-18

    Water vapor is well known to be a critical component in many aspects of atmospheric research, such as radiative transfer and cloud and aerosol processes. This requires both improved measurements of the columnar water vapor and its profiles in the atmosphere in a wide range of conditions, and adjustment of water vapor parameterizations in radiation codes including the perfection of spectroscopic parameters. In this paper we will present the results of comparison of our calculations and downward solar fluxes measured with Rotating Shadowband Spectroradiometer under conditions of horizontally homogeneous clouds. We also will discuss the sensitivity of atmospheric radiation characteristics to variations of water vapor in the band 940 nm: these results may be useful for development of new methods of retrieval of the total column water vapor content (WVC) in the atmosphere from data of radiation observations.

  2. INTERNAL FILTERS: PROSPECTS FOR UV-ACCLIMATION IN HIGHER PLANTS

    EPA Science Inventory

    Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation (400-700nm) to the chloroplasts, while removing much of the damaging ultraviolet-B (UV-B, 280-320 nm) radiation. Flavonoids are important in this wavelength-selective ab...

  3. ED50 determination of corneal lesions produced by 1318-nm laser radiation pulses

    NASA Astrophysics Data System (ADS)

    Ketzenberger, Bryan K.; Johnson, Thomas E.; Wild, Steven P.; Pletcher, Kenneth B.; Roach, William P.

    2001-05-01

    High-energy use of 1318 nm laser systems is becoming more prevalent in military and industrial settings. Threshold, ED50, exposure data and mechanism of laser-tissue interaction need to be determined for this wavelength using appropriate animal models that allow for extrapolation to control human exposures. Threshold, ED50, exposure data at 1318 nm for retinal and corneal injury have previously been undertaken and reported for rhesus monkeys. Using comparable methods, we examine exposure data at 1318 nm to determine the ED50 and laser-tissue interaction in the rabbit model to evaluate cornea. We present preliminary data for the ED50 threshold on the cornea from exposure to 1318 nm single laser pulses. Delivery of laser energy is accomplished using an Nd:YAG system producing 1318 nm light in the 0.5 millisecond time exposure regime and in the range of 0 to 500 mJ. Results from this work will aid in the establishment of safety standards for near infrared laser systems.

  4. Evaluation of cytotoxicity and radiation enhancement using 1.9 nm gold particles: potential application for cancer therapy

    NASA Astrophysics Data System (ADS)

    Butterworth, K. T.; Coulter, J. A.; Jain, S.; Forker, J.; McMahon, S. J.; Schettino, G.; Prise, K. M.; Currell, F. J.; Hirst, D. G.

    2010-07-01

    High atomic number (Z) materials such as gold preferentially absorb kilovoltage x-rays compared to soft tissue and may be used to achieve local dose enhancement in tumours during treatment with ionizing radiation. Gold nanoparticles have been demonstrated as radiation dose enhancing agents in vivo and in vitro. In the present study, we used multiple endpoints to characterize the cellular cytotoxic response of a range of cell lines to 1.9 nm gold particles and measured dose modifying effects following transient exposure at low concentrations. Gold nanoparticles caused significant levels of cell type specific cytotoxicity, apoptosis and increased oxidative stress. When used as dose modifying agents, dose enhancement factors varied between the cell lines investigated with the highest enhancement being 1.9 in AGO-1522B cells at a nanoparticle concentration of 100 µg ml - 1. This study shows exposure to 1.9 nm gold particles to induce a range of cell line specific responses including decreased clonogenic survival, increased apoptosis and induction of DNA damage which may be mediated through the production of reactive oxygen species. This is the first study involving 1.9 nm nanometre sized particles to report multiple cellular responses which impact on the radiation dose modifying effect. The findings highlight the need for extensive characterization of responses to gold nanoparticles when assessing dose enhancing potential in cancer therapy.

  5. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    SciTech Connect

    Rybaltovsky, A A; Sokolov, V O; Plotnichenko, V G; Lanin, Aleksei V; Semenov, S L; Dianov, Evgenii M; Gur'yanov, A N; Khopin, V F

    2007-04-30

    The photoinduced room-temperature-stable increase in the refractive index by {approx}5x10{sup -4} at a wavelength of 1.55 {mu}m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms with a phosphosilicate glass core and optical fibres fabricated from them are studied in a broad spectral range from 150 to 5000 nm. The intense induced-absorption band ({approx}800 cm{sup -1}) at 180 nm is found, which strongly affects the formation of the induced refractive index. The quantum-chemical model of a defect related to this band is proposed. (optical fibres)

  6. Formation of Micro and Nano Structures Using VUV 157 nm Laser Radiation

    SciTech Connect

    Walton, C. D.; Cockcroft, S.

    2010-10-08

    We report on laser ablation experiments on micro and nano size composite structures. The surface of CR-39 and polycarbonate has been intentionally seeded with silicon carbide and silver nanowires and subsequently laser irradiated at a wavelength of 157 nm. We show scanning electron micrograph images of prismatic and conical structures produced by laser ablation and discuss a shape transformation from a prismatic to a conical structure.

  7. Mitochondrial dependent oxidative stress in cell culture induced by laser radiation at 1265 nm.

    PubMed

    Saenko, Yury V; Glushchenko, Eugenia S; Zolotovskii, Igor O; Sholokhov, Evgeny; Kurkov, Andrey

    2016-04-01

    Photodynamic therapy is the main technique applied for surface carcinoma treatment. This technique employs singlet oxygen generated via a laser excited photosensitizer as a main damaging agent. However, prolonged sensitivity to intensive light, relatively low tissue penetration by activating light the cost of photosensitizer (PS) administration can limit photodynamic therapy applications. Early was reported singlet oxygen generation without photosensitizer induced by a laser irradiation at the wavelength of 1250-1270 nm. Here, we study the dynamics of oxidative stress, DNA damage, changes of mitochondrial potential, and mitochondrial mass induced by a laser at 1265 nm have been studied in HCT-116 and CHO-K cells. Laser irradiation of HCT-116 and CHO-K cells has induced a dose-dependent cell death via increasing intracellular reactive oxygen species (ROS) concentration, increase of DNA damage, decrease of mitochondrial potential, and reduced glutathione. It has been shown that, along with singlet oxygen generation, the increase of the intracellular ROS concentration induced by mitochondrial damage contributes to the damaging effect of the laser irradiation at 1265 nm. PMID:26796703

  8. Carcinogenesis induced by UVA (365-nm) radiation: the dose-time dependence of tumor formation in hairless mice.

    PubMed

    de Laat, A; van der Leun, J C; de Gruijl, F R

    1997-05-01

    Although ultraviolet B (UVB wavelengths 280-315 nm) dominates the carcinogenic effect of sunlight, ultraviolet A (UVA 315-400 nm) is estimated to contribute 10-20% to the carcinogenic dose; a substantial background that is not affected by a depletion of the ozone layer. Furthermore, certain high-power modern tanning lamps emit mainly long wave UVA (UVA1; 340-400 nm). For a proper risk estimate of UVA exposure its carcinogenicity relative to that of UVB exposure needs to be determined more accurately. To this end we determined the dose-time relationship for skin tumor induction in hairless mice that were irradiated daily with custom-made Philips 365-nm sources. Irradiation of the group exposed to the highest of the four daily doses (430, 240, 140 and 75 kJ/m2) had to be discontinued because severe scratching set in after 3 months (no tumors). In the lower dose-groups the prevalence curves for skin carcinomas (percentage of tumor-bearing mice versus logarithm of time) ran virtually parallel, and were similar to those found with daily UVB exposure. However, the relationship between the daily dose (D) and the median tumor induction time (t50) appeared to differ: with UVB we found that t50 D(r) = constant, with r = 0.6, whereas with UVA1 we found r approximately 0.4. This would imply that 365-nm carcinogenesis shows less of a dose-dependency than UVB carcinogenesis, and that 365-nm radiation becomes more carcinogenic, relative to UVB, as the daily doses are lowered. This relative shift at low doses complicates extrapolation of UVB to UVA risks in humans. Based on the t50 from the lowest dose-group we found that the carcinogenicity at 365 nm (per J/m2) is 0.9 x 10(-4) times that at 293 nm, the wavelength of maximum carcinogenicity in hairless mice. This result for 365-nm carcinogenicity falls well within the margins of error of the wavelength dependency that was estimated earlier from experiments with broadband UV sources. PMID:9163689

  9. Impact of ultraviolet-B radiation on planktonic fish larvae: alteration of the osmoregulatory function.

    PubMed

    Sucré, Elliott; Vidussi, Francesca; Mostajir, Behzad; Charmantier, Guy; Lorin-Nebel, Catherine

    2012-03-01

    Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 μWcm(-2): 4 h L/20 h D) and medium (80 μWcm(-2): 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na+/K(+)-ATPase and the Na+/K+/2Cl- cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR. PMID:22018917

  10. Radiation hardness of a 180 nm SOI monolithic active pixel sensor

    NASA Astrophysics Data System (ADS)

    Fernandez-Perez, S.; Backhaus, M.; Pernegger, H.; Hemperek, T.; Kishishita, T.; Krüger, H.; Wermes, N.

    2015-10-01

    The use of Silicon-on-Insulator (SOI) technology as a particle detector in a high radiation environment is, at present, limited mostly by radiation effects on the transistor characteristics, back gate effect, and mutual coupling between the Buried Oxide (BOX) and the sensor. We have fabricated and tested a new 0.18 μm SOI CMOS monolithic pixel sensor using the XFAB process. In contrast to the most commonly used SOI technologies, this particular technology uses partially depleted SOI transistors, offering a double well structure, which shields the thin gate oxide transistors from the BOX. In addition, an increased distance between transistors and a thicker BOX than has been previously used offers promising solutions to the performance limitations mentioned above. The process further allows the use of high voltages (up to 200 V), which are used to partially deplete the substrate. Thus, the newly fabricated device in the XFAB process is especially interesting for applications in extremely high radiation environments, such as LHC experiments. A four stage validation programme of the technology and the fabricated monolithic pixel sensor has been performed and its results are shown in this paper. The first targets radiation hardness of the transistor characteristics up to 700 Mrad, the second investigates the existence of the back gate effect, the third one targets the coupling between the BOX and the sensor, and the fourth investigates the characterization of charge collection in the sensor diode below the BOX.

  11. Corneal thermal damage threshold dependence on the exposure duration for near-infrared laser radiation at 1319 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jiarui; Jiao, Luguang; Chen, Hongxia; Yang, Zaifu; Hu, Xiangjun

    2016-01-01

    The corneal damage effects induced by 1319-nm transitional near-infrared laser have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. The in vivo corneal damage thresholds (ED50s) were determined in New Zealand rabbits for 1319-nm laser radiation for exposure durations from 75 ms to 10 s. An additional corneal ED50 was determined at 1338 nm for a 5-ms exposure. The incident corneal irradiance diameter was fixed at 2 mm for all exposure conditions to avoid the influence of spot size on threshold. The ED50s given in terms of the corneal radiant exposure for exposure durations of 5 ms, 75 ms, 0.35 s, 2 s, and 10 s were 39.4, 51.5, 87.2, 156.3, and 311.1 J/cm2, respectively. The 39.4 J/cm2 was derived from the ED50 for 1338 nm (27.0 J/cm2). The ED50s for exposure durations of 75 ms to 10 s were correlated by a power law equation, ED50=128.9t0.36 in J/cm2, where t was the input in the unit of second, with correlation coefficient (R) of 0.997. Enough safe margins existed between the ED50s and the maximum permitted exposures from current laser safety standard.

  12. Radiation sensitive developable bottom anti-reflective coatings (DBARC) for 193nm lithography: first generation

    NASA Astrophysics Data System (ADS)

    Toukhy, Medhat; Oberlander, Joseph; Mullen, Salem; Lu, PingHung; Neisser, Mark

    2007-03-01

    A first generation DBARC applicable for 1 st minimum 193nm lithography is described in this paper. The polymer used in this DBARC is insoluble in the casting solvent of the resist, which is propyleneglycolmonomethyletheracetate (PGMEA). Photo acid generator (PAG) and base extractions from the DBARC coating by the resist casting solvent were examined by the DBARC dissolution rates in the developer, before and after solvent treatments. Although the resist and the DBARC do not appear to intermix, strong interaction between the two is evident by their lithographic performance and dissolution rate study.

  13. Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

    SciTech Connect

    Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

    2010-07-10

    Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

  14. Radiation-enhanced gate-induced-drain-leakage current in the 130 nm partially-depleted SOI pMOSFET

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Hu, Zhiyuan; Ning, Bingxu; Dai, Lihua; Bi, Dawei; Zhang, Zhengxuan

    2015-04-01

    The total ionizing dose (TID) effect of the pMOSFET from 130 nm partially-depleted silicon-on-insulator (PDSOI) is investigated. The data obtained from 60Co γ-ray irradiation experiments indicate that input/output (I/O) device is more susceptible to TID effect than the core device. An anomalous off-state leakage increase is observed for I/O pMOSFET when drain is biased at a high voltage after irradiation. It is proved that this radiation-induced leakage relates to the enhanced gate-induce-drain-leakage (GIDL). Both the radiation-induced interface traps at the gate-oxide/body interface and the oxide trapped charges in the buried oxide (BOX) are responsible for the growth of the leakage current. These conclusions are also verified by the TCAD simulations. The isothermal annealing can recover the leakage current to the pre-irradiation level.

  15. The direct measurement of ablation pressure driven by 351-nm laser radiation

    NASA Astrophysics Data System (ADS)

    Fratanduono, D. E.; Boehly, T. R.; Celliers, P. M.; Barrios, M. A.; Eggert, J. H.; Smith, R. F.; Hicks, D. G.; Collins, G. W.; Meyerhofer, D. D.

    2011-10-01

    The instantaneous scaling of ablation pressure to laser intensity is directly inferred for ramp compression of diamond targets irradiated by 351-nm light. Continuously increasing pressure profiles from 100 to 970 GPa are produced by direct-drive laser ablation at intensities up to 7 × 1013 W/cm2. The free-surface velocity on the rear of the target is used to directly infer the instantaneous ablation-pressure profile at the front of the target. The laser intensity on target is determined by laser power measurements and fully characterized laser spots. The ablation pressure is found to depend on the laser intensity as P(GPa )=42(±3)[I(TW/cm2)]0.71(±0.01).

  16. Ultraviolet radiation and immunology: something new under the sun--presidential address.

    PubMed

    Kripke, M L

    1994-12-01

    The carcinogenic activity of solar radiation has been known for nearly a century. However, within the past few years, we have realized that exposing the skin to sunlight also has profound immunological effects on the host and that these immunological changes can contribute to the development of skin cancer and alter host resistance to infectious diseases. These findings have led to the development of a new field of research, termed photoimmunology, which is concerned with the effects of UV radiation on immunological processes. Our interest in this field arose from studies on the antigenic properties of skin cancers induced in mice by chronic exposure to UV-B (280-320 nm) radiation. These cancers are highly antigenic and many are immunologically rejected upon transplantation to normal syngeneic recipients. In studying how these cancers were able to survive and grow in the primary host, we discovered that exposing the skin to UV radiation altered some types of immune responses, including the immune response against skin cancers. Studies on the nature and mechanism of the immunological alterations brought about by exposure to UV radiation suggested that UV-induced DNA damage triggers a cascade of events, leading ultimately to a state of antigen-specific, systemic T lymphocyte-mediated immunosuppression. Key components of this cascade are epidermal cytokines, which modulate the immune response to antigens introduced into the UV-irradiated host and divert the response toward a state of specific immunosuppression. The finding that UV radiation can redirect the immune response from an effector to a suppressor pathway has raised the possibility that immune responses to infectious diseases might also be influenced by exposure of the host to UV radiation. Interest in the health consequences of stratospheric ozone depletion, with its attendant increase in solar UV-B radiation, has stimulated recent investigations on the effects of UV radiation on the pathogenesis of

  17. Analysis of the efficiency of using 1265-nm cw laser radiation for initiating oxidative stress in the tissue of a solid malignant tumour

    SciTech Connect

    Gening, T P; Voronova, O S; Dolgova, D R; Abakumova, T V; Zolotovskii, Igor' O; Sholokhov, E M; Kurkov, Andrei S; Gening, S O

    2012-09-30

    The possibility of laser initiation of oxidative stress was studied by the example of the tumour tissue of cervix. The laser facility with the operating wavelength 1265 nm that falls within the region of resonance absorption of molecular oxygen was used for initiation. The source of radiation in the experiments was a fibre SRS laser with the repeated cascade conversion of radiation of a 1125-nm ytterbium laser. (optical fibres, lasers and amplifiers. properties and applications)

  18. Dual calibrated dosimeter for simultaneous measurements of erythemal and vitamin D effective solar ultraviolet radiation.

    PubMed

    Wainwright, L; Parisi, A V; Downs, N

    2016-04-01

    A miniaturized ultraviolet radiation (UV) dosimeter based on polyphenylene oxide (PPO) has been dual calibrated for both erythemal and vitamin D effective exposures (UVB 280 - 320 nm) over extended periods up to five days. Optimal human health requires a balanced amount of UVB exposure as both too much and too little have different but serious potential health consequences. Dosimetry is an established method of measuring specific UV exposures to an object or subject. PPO dosimeters have previously been used to measure the erythemally effective UV exposure. An extension of this use is to dual calibrate the miniaturized dosimeter which will also enable measurement of vitamin D effective exposures. By calibration to the erythemal and vitamin D effective action spectra, PPO dosimeters were able to record both types of biologically effective exposure as both are active within the UVB waveband. Dose response tests were conducted in each season by exposure to solar UV with the corresponding dual calibrations made for each season. The calibration provided an R(2) of 0.95-0.99 for erythemal UV and an R(2) of 0.99 for vitamin D effective UV. The successful outcome of this testing has established that PPO is suitable for use as a long term, dual calibrated dosimeter provided the film is seasonally calibrated. This enables one dosimeter to provide two sets of exposure results. The combination of dual calibration and the long term exposure potential of PPO makes the PPO dosimeter more versatile and increases the scope of UV field research on erythemal UV and vitamin D effective UV in the future. PMID:26878218

  19. Near ultraviolet radiation (280-400 nm): Direct and indirect effects on microbial pathogens

    SciTech Connect

    Asthana, A.

    1993-01-01

    Responses of pigmented pathogenic fungi and E. coli strains differing in DNA repair and catalase proficiency to direct and indirect effects of ultraviolet radiation were evaluated. Pigments in the four fungal pathogens of Citrus differed in their ability to protect against direct UV and damage by UV-A -mediated phototoxins of both host and non-host origin. UV-A and UV-B did not inactivate the fungal species. Differential protection in wild type strains of the two Fusarium spp. and in the wild type strains of the two Penicilium spp. against UV-C was observed. Wild type and mutants with altered coloration in Penicilium spp. protected to varying extent against both [alpha]-T and 8-MOP in the presence of UV-A. UV-B irradiation of E. coli resulted in inactivation of strains deficient in DNA excision repair. Plasmid DNA damaged in vitro by UV-B from lamp systems as well as by sunlight, and transformed in vivo into bacterial cells lacking specific nucleases showed reduced transformation in DNA excision repair strains. UV-B enriched wavelengths isolated from a solar simulator affected plasmid DNA in a similar manner as UV-B from lamp systems. Sunlight, however affected the membrane of whole cells. Concentration of foliar furanocoumarins of Citrus jambhiri decreased with UV-B irradiation. Phototoxicity to Fusarium spp. was accounted for, in part, by furanocoumarins, psoralen and bergapten (5-MOP) and others. Pure psoralen and 5-MOP affected both Fusarium spp. similarly and carotenoids protected only partially in the wild type strains. Citrus targetted the cell membrane in Fusarium spp.l and in E. coli strains; carotenoids in both of which protected against such damage. Loss in structural integrity of plasmid DNA when treated with citral and UV-A correlated with loss in transforming activity. Biological damage to membrane and DNA was due to the production of hydrogen peroxide. Fruit-rot pathogens Penicilium spp. were not affected by either furanocoumarins or citrals.

  20. Generation of continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling of a Ti:sapphire laser.

    PubMed

    Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

    2010-03-20

    We have generated continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling a high-power Ti:sapphire laser in an external enhancement cavity. An LBO crystal that is Brewster-cut and antireflection coated on both ends is used for a long-term stable frequency doubling. By optimizing the input coupler's reflectivity, we could generate 1.5 W 378 nm radiation from a 5 W 756 nm Ti:sapphire laser. According to our knowledge, this is the highest CW frequency-doubled power of a Ti:sapphire laser. PMID:20300165

  1. A dual redundancy radiation-hardened flip—flop based on a C-element in a 65 nm process

    NASA Astrophysics Data System (ADS)

    Gang, Chen; Bo, Gao; Min, Gong

    2013-09-01

    A radiation-hardened flip—flop is proposed to mitigate the single event upset (SEU) effect. Immunity was achieved through the use of C-elements and redundant storage elements. It takes advantage of the property of a C-element in which it enters a high impedance mode when its inputs are of different logic values. Redundant storage nodes are then used to drive the C-elements so that a single upset pulse in any storage will be prevented from altering the state of the output of the flip—flop. The flip—flop was implemented using 48 transistors and occupied an area of 30.78 μm2, using 65 nm CMOS process. It consumed 22.6% fewer transistors as compared to the traditional SEU resilient TMR flip—flop.

  2. Ocular temperature elevation induced by threshold in vivo exposure to 1090-nm infrared radiation and associated heat diffusion

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per G.

    2014-10-01

    An in vivo exposure to 197 W/cm2 1090-nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as a confidence interval (0.95), was 11±3°C at the limbus, 16±6°C in the vitreous behind lens, and 16±7°C on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1°C at the limbus and 26±11°C on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090-nm IRR for 8 s induces a temperature increase of 10°C at the limbus and 26°C close to the retina. IRR cataract is probably of thermal origin.

  3. Sea ice protects the embryos of the Antarctic sea urchin Sterechinus neumayeri from oxidative damage due to naturally enhanced levels of UV-B radiation.

    PubMed

    Lister, Kathryn N; Lamare, Miles D; Burritt, David J

    2010-06-01

    The 'ozone hole' has caused an increase in ultraviolet B radiation (UV-B, 280-320 nm) penetrating Antarctic coastal marine ecosystems, however the direct effect of this enhanced UV-B on pelagic organisms remains unclear. Oxidative stress, the in vivo production of reactive oxygen species to levels high enough to overcome anti-oxidant defences, is a key outcome of exposure to solar radiation, yet to date few studies have examined this physiological response in Antarctic marine species in situ or in direct relation to the ozone hole. To assess the biological effects of UV-B, in situ experiments were conducted at Cape Armitage in McMurdo Sound, Antarctica (77.06 degrees S, 164.42 degrees E) on the common Antarctic sea urchin Sterechinus neumayeri Meissner (Echinoidea) over two consecutive 4-day periods in the spring of 2008 (26-30 October and 1-5 November). The presence of the ozone hole, and a corresponding increase in UV-B exposure, resulted in unequivocal increases in oxidative damage to lipids and proteins, and developmental abnormality in embryos of S. neumayeri growing in open waters. Results also indicate that embryos have only a limited capacity to increase the activities of protective antioxidant enzymes, but not to levels sufficient to prevent severe oxidative damage from occurring. Importantly, results show that the effect of the ozone hole is largely mitigated by sea ice coverage. The present findings suggest that the coincidence of reduced stratospheric ozone and a reduction in sea ice coverage may produce a situation in which significant damage to Antarctic marine ecosystems may occur. PMID:20472784

  4. Impact of ultraviolet radiation on cell structure, UV-absorbing compounds, photosynthesis, DNA damage, and germination in zoospores of Arctic Saccorhiza dermatodea.

    PubMed

    Roleda, Michael Y; Wiencke, Christian; Lüder, Ulrike H

    2006-01-01

    Stratospheric ozone depletion leads to enhanced UV-B radiation. Therefore, the capacity of reproductive cells to cope with different spectral irradiance was investigated in the laboratory. Zoospores of the upper sublittoral kelp Saccorhiza dermatodea were exposed to varying fluence of spectral irradiance consisting of photosynthetically active radiation (PAR, 400-700 nm; =P), PAR+UV-A radiation (UV-A, 320-400 nm; =PA), and PAR+UV-A+UV-B radiation (UV-B, 280-320 nm; =PAB). Structural changes, localization of phlorotannin-containing physodes, accumulation of UV-absorbing phlorotannins, and physiological responses of zoospores were measured after exposure treatments as well as after 2-6 d recovery in dim white light (8 mumol photon m(-2) s(-1)). Physodes increased in size under PAB treatment. Extrusion of phlorotannins into the medium and accumulation of physodes was induced not only under UVR treatment but also under PAR. UV-B radiation caused photodestruction indicated by a loss of pigmentation. Photosynthetic efficiency of spores was photoinhibited after 8 h exposure to 22 and 30 mumol photon m(-2) s(-1) of PAR, while supplement of UVR had a significant additional effect on photoinhibition. A relatively low recovery of photosystem II function was observed after 2 d recovery in spores exposed to 1.7 x 10(4) J m(-2) of UV-B, with a germination rate of only 49% of P treatment after 6 d recovery. The amount of UV-B-induced DNA damage measured as cyclobutane-pyrimidine dimers (CPDs) increased with the biologically effective UV-B dose (BED(DNA)). Significant removal of CPDs indicating repair of DNA damage was observed after 2 d in low white light. The protective function of phlorotannins has restricted efficiency for a single cell. Within a plume of zoospores, however, each cell can buffer each other and protect the lower layer of spores from excessive radiation. Exudation of phlorotannins into the water can also reduce the impact of UV-B radiation on UV-sensitive spores

  5. Generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet radiation at 271.2 nm.

    PubMed

    Biswal, Ramakanta; Agrawal, Praveen K; Dixit, Sudhir K; Nakhe, Shankar V

    2015-11-10

    This paper presents to our knowledge a first time study on the generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet (UV) radiation at 271.2 nm. The work is based on frequency summing of coherent green (G: 510.6 nm) and yellow (Y: 578.2 nm) radiations of a copper-HBr laser in a β-barium borate crystal. Average and peak sum frequency conversion efficiencies of about 13% and 16%, respectively, are obtained. The sum frequency results are experimentally analyzed in terms of the extent of matching of green and yellow pump radiations in space, time, and frequency domains. The result is of high significance for many applications in photonics components fabrication, semiconductor technology, and spectroscopy. PMID:26560794

  6. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm.

    PubMed

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-05-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t (0.66) [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards. PMID:27231639

  7. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm

    PubMed Central

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-01-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t0.66 [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards. PMID:27231639

  8. Monopersulfate photocatalysis under 365 nm radiation. Direct oxidation and monopersulfate promoted photocatalysis of the herbicide tembotrione.

    PubMed

    Solís, Rafael R; Rivas, F Javier; Tierno, Mercedes

    2016-10-01

    Oxone(®) (potassium monopersulfate, MPS) has been used to oxidize the herbicide tembotrione in aqueous solution. Tembotrione elimination kinetics by MPS direct oxidation has been studied. The influence of the main operating variables affecting the process (MPS concentration, temperature and pH) has been evaluated. The process follows 2/3 and first orders in MPS and tembotrione concentrations, respectively. Optimal pH is located around circumneutral conditions. MPS decomposition in the presence of 365 nm UVA radiation and titanium dioxide has also been studied. A kinetic mechanism that simulates MPS decomposition has been proposed, showing the positive effect of titania load and MPS concentration. The system MPS/UVA/TiO2 significantly improves tembotrione and mineralization rate abatement if compared to runs conducted in the absence of MPS. Tembotrione total abatement was achieved in 20 min when 0.05 g L(-1) of titania and 10(-4) M of Oxone(®) were used. TOC conversion was roughly 70% in 90 min under similar operating conditions. An experimental design (Plackett-Burman) has been considered to study the influence of the main variables affecting tembotrione photocatalytic oxidation promoted by MPS. PMID:27393945

  9. EFFECT OF LOCAL ULTRAVIOLET IRRADIATION ON INFECTIONS OF MICE WITH CANDIDA ALBICANS, MYCOBACTERIUM BOVIS BCG, AND SCHISTOSOMA MANSONI

    EPA Science Inventory

    In this study, we investigated whether mice given ultraviolet (UV)-B (280-320 nm) radiation in doses sufficient to alter cutaneous immune ce//s and impair the induction of contact hypersensitivity would also have impaired resistance to infectious agents administered at the site o...

  10. Coupling Short-term Changes in Ambient UV-B levels with induction of UV-screening compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A substantial number of studies have been conducted over the last several decades to assess the potential impacts of long-term increases in UV-B radiation (UV-B between 280-320 nm) that might result from continued depletion of stratospheric ozone. However, in addition to stratospheric ozone levels ...

  11. Spaced sensor measurements of artificial airglow emission at 630 nm of ionosphere caused by ``Sura'' facility radiation in November 2013

    NASA Astrophysics Data System (ADS)

    Nasyrov, Igor; Grach, Savely; Gumerov, Rustam; Shindin, Alexey; Kogogin, Denis; Dementiev, Vladislav

    Some first results on simultaneous observation artificial airglow emission at 630 nm during HF pumping of the ionosphere by “Sura” facility from two spatial situated experimental sites are reported. The measurements of artificial airglow are usually conducted in red and green lines of atomic oxygen (the radiation of levels O((1) D) and O((1) S) under their excitation by electronic impact) with wave lengths of 630 and 557.7 nm and excitation energy of 1.96 and 4.17 eV accordingly. An enhancement of airglow intensity in the red line is related at present to the electron heating by powerful radio waves. The idea of the experiment was to estimate the heated volume three-dimensional structure and drift motion one. The experiment was carried out in November 2013 at the “Sura” radio facility, situated near Nizhny Novgorod, Russia (geographical coordinates 56.13(o) N, 46.10(o) E, geomagnetic field declination and inclination are ˜ 10.0(o) east and ˜ 71.5(o) , respectively). Conditions of ionosphere were checked by means of "Cady" ionosonde during “Sura” runs. According to the ionospheric conditions, on the 7(th) of November the “Sura” facility operated at frequency 4.540 MHz. At this frequency the effective radiated power was about 120MW. The HF beam width at the “Sura” facility is ˜ 12(o) . A square wave pump modulation of 5 min on, 5 min off, was used. Measurements were carried out in the period from 14:40 to 17:30 UTC. Optical imaging was performed on two spatial experimental sites: “Vasilsursk” (situated about 500 m from antenna system of “Sura” facility); “Raifa” (situated about 170 km from “Sura” facility at the Magnetic Observatory of Kazan Federal University, geographical coordinates 55.93(o) N, 48.75(o) E). They both were fitted out Peltier-cooled front-illuminated bare CCD cameras with 16-bit slow-scan read-out (S1C3). On “Vasilsursk” site the images were binned down to 256× 256 pixels in addition to cooling, in order

  12. The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

    SciTech Connect

    Vasilyak, L. M.; Drozdov, L. A. Kostyuchenko, S. V.; Sokolov, D. V.; Kudryavtsev, N. N.; Sobur, D. A.

    2011-12-15

    The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

  13. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per

    2015-01-01

    The damage mechanism for near-infrared radiation (IRR) induced cataract is unclear. Both a photochemical and a thermal mechanism were suggested. The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity. Groups of 20 rats were unilaterally exposed to 96-W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, and 344 kJ/cm2, respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was quantitatively measured. The average maximum temperature increases for exposure times of 10, 18, 33, and 60 min were expressed as 7.0±1.1, 6.8±1.1, 7.6±1.3, and 7.4±1.1°C [CI (0.95)] at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not-exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, and -0.01±0.03 transformed equivalent diazepam concentration (tEDC), respectively, and no apparent morphological changes in the lens were observed. An exposure to 96-W/cm2 1090-nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is <8°C. This is consistent with a thermal damage mechanism for IRR-induced cataract.

  14. Visible optical radiation generates bactericidal effect applicable for inactivation of health care associated germs demonstrated by inactivation of E. coli and B. subtilis using 405-nm and 460-nm light emitting diodes

    NASA Astrophysics Data System (ADS)

    Hönes, Katharina; Stangl, Felix; Sift, Michael; Hessling, Martin

    2015-07-01

    The Ulm University of Applied Sciences is investigating a technique using visible optical radiation (405 nm and 460 nm) to inactivate health-hazardous bacteria in water. A conceivable application could be point-of-use disinfection implementations in developing countries for safe drinking water supply. Another possible application field could be to provide sterile water in medical institutions like hospitals or dental surgeries where contaminated pipework or long-term disuse often results in higher germ concentrations. Optical radiation for disinfection is presently mostly used in UV wavelength ranges but the possibility of bacterial inactivation with visible light was so far generally disregarded. One of the advantages of visible light is, that instead of mercury arc lamps, light emitting diodes could be used, which are commercially available and therefore cost-efficient concerning the visible light spectrum. Furthermore they inherit a considerable longer life span than UV-C LEDs and are non-hazardous in contrast to mercury arc lamps. Above all there are specific germs, like Bacillus subtilis, which show an inactivation resistance to UV-C wavelengths. Due to the totally different deactivation mechanism even higher disinfection rates are reached, compared to Escherichia coli as a standard laboratory germ. By 460 nm a reduction of three log-levels appeared with Bacillus subtilis and a half log-level with Escherichia coli both at a dose of about 300 J/cm². By the more efficient wavelength of 405 nm four and a half log-levels are reached with Bacillus subtilis and one and a half log-level with Escherichia coli also both at a dose of about 300 J/cm². In addition the employed optical setup, which delivered a homogeneous illumination and skirts the need of a stirring technique to compensate irregularities, was an important improvement compared to previous published setups. Evaluated by optical simulation in ZEMAX® the designed optical element provided proven

  15. Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair.

    PubMed

    Wong, Chiew-Yen; Teoh, Ming-Li; Phang, Siew-Moi; Lim, Phaik-Eem; Beardall, John

    2015-01-01

    Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR), have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237), temperate (Chlorella vulgaris UMACC 248) and tropical (Chlorella vulgaris UMACC 001) environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400-700 nm), PAR plus ultraviolet-A (320-400 nm) radiation (PAR + UV-A) and PAR plus UV-A and ultraviolet-B (280-320 nm) radiation (PAR + UV-A + UV-B) for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM) fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek) and light harvesting efficiency (α) were determined from rapid light curves. The damage (k) and repair (r) rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B) and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r) mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain

  16. Dithymine photodimers and photodecomposition products of thymidylyl-thymidine induced by ultraviolet radiation from 150 to 300 nm

    SciTech Connect

    Saitou, M.; Hieda, K.

    1994-11-01

    Solid thymidylyl-(3{prime} {yields} 5{prime})-thymidine (dTpdT) was irradiated in a vacuum with monochromatic photons from 150 to 300 nm; the photoproducts were analyzed quantitatively by high-performance liquid chromatography. The results of the experiment were as follows: (1) above 210 nm the major photoproducts were three dithymine photodimers [the cis-syn and trans-syn cyclobutane thymine dimers and the thymine (6-4) photoproduct]; below 210 nm, they were three photodecomposition products (thymine, thymidine 5{prime}-monophosphate and thymidine 3{prime}-monophosphate). This shows that 210 nm is the wavelength at which the major photoproducts change from dithymine photodimers (far-UV type) to photodecomposition products (X-ray type). (2) The yields of the three dithymine photodimers had a similar wavelength dependence with each other: the yields had a peak at 260 nm and gradually decreased toward shorter wavelengths to 150 nm. (3) The yields of the three photodecomposition products also had a very similar wavelength dependence with each other; the yields increased exponentially with a decrease in the wavelength. (4) The average ratios of the yield of the (6-4) photoproduct to that of the cis-syn dimer were 0.30 between 170 and 220 nm, but 0.16 between 240 and 290 nm. 18 refs., 4 figs.

  17. Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He – Ar plasma containing nanoclusters of uranium compounds

    SciTech Connect

    Kosarev, V A; Kuznetsova, E E

    2014-02-28

    The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He – Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He – Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide. (lasers)

  18. Generation of tunable 187.9-196-nm radiation in beta-BaB(2)O(4): errata.

    PubMed

    Bhar, G C; Chatterjee, U; Rudra, A M; Kumbhakar, P; Route, R K; Feigelson, R S

    1998-02-15

    In Ref. 1, the first full sentence in the right-hand column of p. 1608 should read as: 'Although BBO is phase matchable down to 187 nm and shorter in this configuration without a very large (2-4 degrees ) change in theta (and hence in d(eff)), and B2 is also suitable to accommodate the phase matching, tunability below 187.9 nm becomes limited by the exponential increase in crystal absorption.' PMID:18084495

  19. Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

    2000-01-01

    Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P<=0.015), with smaller but significant increases at five of the nine South American sites (r(exp 2) = 0.24-0.42; P<=0.05). The contribution of the highest UV-B(sub ery) exposure levels (>= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

  20. Estimation of sea surface solar radiation at 400-700 nm using satellite ocean color data, and its validation by ship data.

    PubMed

    Vazyulya, S V; Kopelevich, O V; Sheberstov, S V; Artemiev, V A

    2016-03-21

    We present results of validating the algorithms used to estimate sea surface solar radiation at 400-700 nm, photosynthetically available radiation (PAR), from satellite ocean color data and an appropriate validation procedure when data are collected using a moving ship. The validation was performed using field measurements of PAR during a transit cruise from the Baltic to the White Sea during the summer of 2014. The PAR was measured at 10-minute intervals using a deck radiometer throughout the daylight hours. The satellite estimate of daily surface PAR with an acceptable error, on the scale of 1 day-102 km, is shown. PMID:27136880

  1. Synchrotron X-ray phase contrast imaging of leaf venation in soybean (Glycine max) after exclusion of solar UV (280-400 nm) radiation.

    PubMed

    Fatima, A; Kataria, S; Guruprasad, K N; Agrawal, A K; Singh, B; Sarkar, P S; Shripathi, T; Kashyap, Y; Sinha, A

    2016-05-01

    The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280-315 nm) or UVAB (280-400 nm), or transmitted all the ambient solar UV (280-400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis. PMID:27140160

  2. UV - ALBUQUERQUE NM

    EPA Science Inventory

    Brewer 109 is located in Albuquerque NM, measuring ultraviolet solar radiation. Irradiance and column ozone are derived from this data. Ultraviolet solar radiation is measured with a Brewer Mark IV, single-monochrometer, spectrophotometer manufactured by SCI-TEC Instruments, Inc....

  3. The Radiation Enhancement of 15 nm Citrate-Capped Gold Nanoparticles Exposed to 70 keV/μm Carbon Ions.

    PubMed

    Liu, Yan; Liu, Xi; Jin, Xiaodong; He, Pengbo; Zheng, Xiaogang; Ye, Fei; Chen, Weiqiang; Li, Qiang

    2016-03-01

    Radiotherapy is an important modality for tumor treatment. The central goal of radiotherapy is to deliver a therapeutic dose to the tumor as much as possible whilst sparing the surrounding normal tissues. On one hand, heavy ion radiation induces maximum damage at the end of the track (called the Bragg Peak). Hadron therapy based on heavy ions is considered superior to conventional X-rays and γ-rays radiations for tumors sited in sensitive tissues, childhood cases and radioresistant cancers. On the other hand, radiation sensitizers enhanced the radiation effects in tumors by increasing the dose specifically to the tumor cells. Recently, the use of gold nanoparticles as potential tumor selective radio-sensitizers has been proposed as a breakthrough in radiotherapy with conventional radiations. The enhanced radiation effect of heavy ions in tumor by using gold nanoparticles as radio-sensitizer may provide alternative in hadron therapy. In this study, we investigated the radiosensitizing effects of carbon ions with a linear energy transfer of 70 keV/μm in the presence of 15 nm citrate-capped AuNPs. The existing of AuNPs resulted in 5.5-fold enhancement in hydroxyl radical production and 24.5% increment in relative biological effectiveness (RBE) values for carbon-ion-irradiated HeLa cells. The study indicated gold nanoparticles can be used as potential radio-sensitizer in carbon ions therapy. PMID:27455642

  4. Preliminary Radiation Testing of a State-of-the-Art Commercial 14nm CMOS Processor/System-on-a-Chip

    NASA Technical Reports Server (NTRS)

    Szabo, Carl M., Jr.; Duncan, Adam; LaBel, Kenneth A.; Kay, Matt; Bruner, Pat; Krzesniak, Mike; Dong, Lei

    2015-01-01

    Hardness assurance test results of Intel state-of-the-art 14nm “Broadwell” U-series processor / System-on-a-Chip (SoC) for total ionizing dose (TID) are presented, along with exploratory results from trials at a medical proton facility. Test method builds upon previous efforts [1] by utilizing commercial laptop motherboards and software stress applications as opposed to more traditional automated test equipment (ATE).

  5. Preliminary Radiation Testing of a State-of-the-Art Commercial 14nm CMOS Processor - System-on-a-Chip

    NASA Technical Reports Server (NTRS)

    Szabo, Carl M., Jr.; Duncan, Adam; LaBel, Kenneth A.; Kay, Matt; Bruner, Pat; Krzesniak, Mike; Dong, Lei

    2015-01-01

    Hardness assurance test results of Intel state-of-the-art 14nm Broadwell U-series processor System-on-a-Chip (SoC) for total dose are presented, along with first-look exploratory results from trials at a medical proton facility. Test method builds upon previous efforts by utilizing commercial laptop motherboards and software stress applications as opposed to more traditional automated test equipment (ATE).

  6. Comparative analysis of cloud effects on ultraviolet-B and broadband solar radiation: Dependence on cloud amount and solar zenith angle

    NASA Astrophysics Data System (ADS)

    El-Nouby Adam, M.; Ahmed, Emad A.

    2016-02-01

    The role played by clouds in atmospheric radiative transfer is fundamental. However, studies of their influences on solar radiation at Qena, Egypt, are lacking. This paper discusses the effect of clouds on the ratio of ultraviolet-B (UVB, 295-2800 nm) to broadband solar radiation (G, 280-320 nm) under all cloud conditions. To achieve this aim, the dependence of cloud modification factors for both UVB and G (CMFUVB and CMFG respectively) on cloud amount (CA) was compared for each category. From 2000 to 2009, the dataset used included hourly values for both UVB and G under all cloud conditions. The results indicated that the average UVB/G ratio for all cloud conditions was 0.25 ± 0.10%. This average represents 76% of the corresponding value under cloudless sky conditions (0.33 ± 0.11%). Accordingly, it indicates that clouds do not transmit UVB and G equally. However, on average, the percentage decrease in CMFUVB from its corresponding value of CMFG was 20 ± 5%. Further analysis for the hourly values of both CMFUVB and CMFG was employed. These hourly values are distinguished by three different behaviors: CMFUVB ≌ CMFG (9% of all cases), CMFUVB > CMFG (11% of all cases), or CMFUVB < CMFG (80% of all cases). The average UVB/G values for each group were 0.27 ± 0.09%, 0.33 ± 0.12%, and 0.23 ± 0.09% respectively. Based on the results of earlier studies, an attempt was made to explain these outcomes. In a more thorough study of CMFUVB and CMFG, the dependence of these variables on SZA was investigated. This analysis has shown that both CMFUVB and CMFG decrease as the SZA increases. For each group, the sensitivities of CMFUVB to SZA were - 0.27 ± 0.03, - 0.32 ± 0.06, and - 0.18 ± 0.03 (respectively); moreover, the sensitivities of CMFG to SZA were - 0.27 ± 0.03, - 0.65 ± 0.05, and - 0.18 ± 0.02 (respectively).

  7. Comparison of theory with atomic oxygen 130.4 nm radiation data from the Bow Shock ultraviolet 2 rocket flight

    NASA Technical Reports Server (NTRS)

    Levin, Deborah A.; Candler, Graham V.; Collins, Robert J.; Howlett, Carl L.; Espy, Patrick; Whiting, Ellis; Park, Chul

    1993-01-01

    Comparison is made between the results obtained from a state-of-the-art flow and radiative model and bow shock vacuum ultraviolet (VUV) data obtained the recent Bow Shock 2 Flight Experiment. An extensive data set was obtained from onboard rocket measurements at a reentry speed of 5 km/sec between the altitudes of approximately 65-85 km. A description of the NO photoionization cell used, the data, and the interpretation of the data will be presented. The primary purpose of the analyses is to assess the utility of the data and to propose a radiation model appropriate to the flight conditions of Bow Shock 2. Theoretical predictions based on flow modeling discussed in earlier work and a new radiation model are compared with data.

  8. The action of NIR (808nm) laser radiation and gold nanorods labeled with IgA and IgG human antibodies on methicillin-resistant and methicillin sensitive strains of Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Petrov, Pavel O.; Ratto, Fulvio; Centi, Sonia; Pini, Roberto; Tuchin, Valery V.

    2015-03-01

    The effect of NIR laser radiation (808 nm) on methicillin-sensitive and methicillin resistant strains of Staphylococcus aureus incubated with gold nanorods is studied. Nanorods having length of 44 (± 4) nm and diameter of 10 (± 3) nm with the absorption maximum in the NIR (800 nm), functionalized with human immunoglobulins IgA and IgG, were synthesized and used in the studies. The killing ability up to 97% of the microorganism populations by using this nanotechnology was shown.

  9. Effects of UV radiation on phytoplankton

    NASA Astrophysics Data System (ADS)

    Smith, Raymond C.; Cullen, John J.

    1995-07-01

    It is now widely documented that reduced ozone will result in increased levels of ultraviolet (UV) radiation, especially UV-B (280-320nm), incident at the surface of the earth [Watson, 1988; Anderson et al., 1991; Schoeberl and Hartmann, 1991; Frederick and Alberts, 1991; WMO, 1991; Madronich, 1993; Kerr and McElroy, 1993], and there is considerable and increasing evidence that these higher levels of UV-B radiation may be detrimental to various forms of marine life in the upper layers of the ocean. With respect to aquatic ecosystems, we also know that this biologically- damaging mid-ultraviolet radiation can penetrate to ecologically- significant depths in marine and freshwater systems [Jerlov, 1950; Lenoble, 1956; Smith and Baker, 1979; Smith and Baker, 1980; Smith and Baker, 1981; Kirk et al., 1994]. This knowledge, plus the dramatic decline in stratospheric ozone over the Antarctic continent each spring, now known to be caused by anthropogenically released chemicals [Solomon, 1990; Booth et al., 1994], has resulted in increased UV-environmental research and a number of summary reports. The United Nations Environmental Program (UNEP) has provided recent updates with respect to the effects of ozone depletion on aquatic ecosystems (Hader, Worrest, Kumar in UNEP 1989, 1991, Hader, Worrest, Kumar and Smith UNEP 1994) and the Scientific Committee on Problems of the Environment (SCOPE) has provided [SCOPE, 1992] a summary of the effects of increased UV radiation on biological systems. SCOPE has also reported [SCOPE, 1993] on the effects of increased UV on the biosphere. In addition, several books have recently been published reviewing various aspects of environmental UV photobiology [Young et al., 1993], UV effects on humans, animals and plants [Tevini, 1993], the biological effects of UV radiation in Antarctica [Weiler and Penhale, 1994], and UV research in freshwater ecosystems [Williamson and Zagarese, 1994]. Several other reviews are relevant [NAS, 1984; Caldwell

  10. Focusing and photon flux measurements of the 2.88-nm radiation at the sample plane of the soft x-ray microscope, based on capillary discharge source

    NASA Astrophysics Data System (ADS)

    Nawaz, M. Fahad; Jancarek, Alexandr; Nevrkla, Michal; Wachulak, Przemyslaw; Limpouch, Jiri; Pina, Ladislav

    2015-05-01

    Feasibility measurements leading to the development of a Soft X-ray (SXR) microscopy setup, based on capillary discharge XUV source is presented. Here the Z-pinching plasma is acting as a source of XUV radiation, emitting incoherent radiation in the "water-window" (λ = 2.3 - 4.4 nm) region of interest (natural contrast between the carbon and oxygen edges).This soft X-ray microscopy setup will realize imaging of the biological objects with high spatial resolution. The 2.88 nm radiation line is filtered out from the water-window band, and is focused by an axi-symmetric ellipsoidal mirror, coated with nickle. The focussed spot size is measured and reported. Flux measurements for the available number of photons (photons/pulse) at the sample plane has been carried out with AXUV PIN diode at the sample plane (slightly out of focus). For imaging, a fresnel zone plate lens will be used as an objective. The overall compact transmission SXR microscopy setup design is presented.

  11. Quasi-continuous-wave 589-nm radiation based on intracavity frequency-doubled Nd:GGG/BaWO4 Raman laser

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Liu, Zhaojun; Cong, Zhenhua; Men, Shaojie; Rao, Han; Xia, Jinbao; Zhang, Sasa; Zhang, Huaijin

    2016-07-01

    Quasi-continuous-wave (QCW) 589-nm radiation was realized based on a frequency-doubled crystalline Raman laser. The fundamental wave with macro-micro-pulse trains was generated from an acousto-optically Q-switched QCW diode side-pumped Nd:GGG laser. Intracavity Raman conversion was accomplished by a BaWO4 crystal and the second harmonic generation was finished by a KTP crystal. Under a pumping power of 126.0 W with a macro-pulse frequency of 300 Hz and duration of 300 μs, the maximum 589 nm output power of 4.2 W was obtained at a micro-pulse frequency of 33.3 kHz. The micro-pulse width was 13.6 ns.

  12. Development of an Adaptive Optical System for Sub-10-nm Focusing of Synchrotron Radiation Hard X-rays

    SciTech Connect

    Mimura, H.; Kimura, T.; Matsuyama, S.; Yokoyama, H.; Yumoto, H.

    2011-09-09

    In the hard x-ray region, to obtain the theoretical resolution or diffraction-limited focusing size in an imaging optical system, both ultraprecise optics and highly accurate alignment are necessary. An adaptive optical system is used for the compensation of aberrations in various optical systems, such as optical microscopes and space telescopes. In situ wavefront control of hard x-rays is also effective for realizing ideal performance. The aim of this paper is to develop an adaptive optical system for sub-10-nm hard x-ray focusing. The adaptive optical system performs the wavefront measurement using a phase retrieval algorithm and wavefront control using grazing-incidence deformable mirrors. Several results of experiments using the developed system are reported.

  13. Transmission of 1064 nm laser radiation during ablation with an ultra-short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Schelle, Florian; Meister, Jörg; Oehme, Bernd; Frentzen, Matthias

    2012-01-01

    During ablation of oral hard tissue with an USPL system a small amount of the incident laser power does not contribute to the ablation process and is being transmitted. Partial transmission of ultra-short laser pulses could potentially affect the dental pulp. The aim of this study was to assess the transmission during ablation and to deduce possible risks for the patient. The study was performed with an Nd:YVO4 laser, emitting pulses with a duration of 8 ps at a wavelength of 1064 nm. A repetition rate of 500 kHz and an average power of 9 W were chosen to achieve high ablation efficiency. A scanner system created square cavities with an edge length of 1 mm. Transmission during ablation of mammoth ivory and dentin slices with a thickness of 2 mm and 5 mm was measured with a power meter, placed directly beyond the samples. Effects on subjacent blood were observed by ablating specimens placed in contact to pork blood. In a separate measurement the temperature increase during ablation was monitored using an infrared camera. The influence of transmission was assessed by tuning down the laser to the corresponding power and then directly irradiating the blood. Transmission during ablation of 2 mm specimens was about 7.7% (ivory) and 9.6% (dentin) of the incident laser power. Ablation of specimens directly in contact to blood caused coagulation at longer irradiation times (t~18s). Direct irradiation of blood with the transmitted power provoked bubbling and smoke formation. Temperature measurements identified heat generation as the main reason for the observed coagulation.

  14. Photoacclimation to long-term ultraviolet radiation exposure of natural sub-Antarctic phytoplankton communities: Fixed surface incubations versus mixed mesocosms.

    PubMed

    Hernando, Marcelo; Schloss, Irene; Roy, Suzanne; Ferreyra, Gustavo

    2006-01-01

    Solar UVB radiation (280-320 nm) is known to have detrimental effects on marine phytoplankton. Associated with the seasonal ozone hole in Antarctica, stratospheric ozone depletion occasionally influences the sub-Antarctic (Beagle Channel, Argentina) region, enhancing levels of UVB. The primary objective of this work was to study the effects of several (i.e. 6-10) days of exposure to UVB on the taxonomic composition and photosynthetic inhibition of local phytoplankton communities. For different light treatments, fixed-depth incubations placed in an outdoors water tank were compared with incubations in 1900 L mesocosms, where vertical mixing was present. Phytoplankton growth was inhibited by UV radiation (UVR) in fixed-depth experiments but not in the mixed mesocosms. Under fixed and mixed conditions alike, photosynthesis was significantly inhibited by UVB at the beginning of the experiment but no longer after several days of exposure, suggesting that cells had acclimated to radiation conditions. There was a change in species composition in response to UVR exposure in both experiments, which likely explained acclimation. In the community exposed to fixed conditions this change was from a phytoflagellate-dominated assemblage to a community with high relative abundance of diatoms after 6 days of exposure. UVA was responsible for most of the observed growth inhibition; however, the reduction in photosynthesis was produced by UVB. The reasons behind this variability in responses to UVR are associated with species-specific sensitivity and acclimation, and the previous light history of cells. In the community exposed in mesocosms, an assemblage codominated by phytoflagellates and diatoms was observed at the beginning of the experiments. After 10 days of exposure, green algae (Eutreptiella sp.) had increased, and phytoflagellates were the dominant group. The synthesis of mycosporine-like amino acids (MAAs), antioxidant enzymes and photosynthetic antenna pigments, in

  15. Mutagenic and lethal effects of near-ultraviolet radiation (290-400 nm) on bacteria and phage

    SciTech Connect

    Eisenstark, A.

    1987-01-01

    Despite decades of study of the effect of near-ultraviolet radiation (NUV) on bacterial cells, insights into mechanisms of deleterious alterations and subsequent recovery are just now emerging. These insights are based on observations that 1) damage by NUV may be caused by a reactive oxygen molecule, since H/sub 2/O/sub 2/ may be a photoproduct of NUV; 2) some, but not all, of the effects of NUV and H/sub 2/O/sub 2/ are interchangeable; 3) there is an inducible regulon (oxyR) that responds to oxidative stress and is involved in protection against NUV; 4) a number of NUV-sensitive mutants are defective either in the capacity to detoxify reactive oxygen molecules or to repair DNA damage caused by NUV; and 5) recovery from NUV damage may not directly involve induction of the SOS response. Since several distinctly different photoreceptors and targets are involved, it is unknown whether NUV lethality and mutagenesis result from an accumulation of damages or whether there is a particularly critical photoeffect. To fully understand the mechanisms involved, it is important to identify the chromophore(s) of NUV, the mechanism of toxic oxygen species generation, the role of the oxidative defense regulon (oxyR), the specific lesions in the DNA, and the enzymatic events of subsequent repair. 131 references.

  16. Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

    PubMed

    Hooke, Rebecca; Pearson, Andy; O'Hagan, John

    2014-01-01

    Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown. PMID:24483759

  17. Transient radiation-induced absorption at 1061 nm in LiNiO[sub 3] and MgO:LiNbO[sub 3

    SciTech Connect

    Brannon, P.J. )

    1994-06-01

    The transient radiation-induced 1061 nm absorption in pure and MgO doped lithium niobate has been measured using Sandia National Laboratories' SPR 3 pulsed nuclear reactor. The samples are subjected to neutron fluences up to 10[sup 13]/cm[sup 2] (1 MeV Si) and total doses up to 7.5 krad. By using various shields, it has been found that gamma rays are the major contributors to the induced absorption at this wavelength. A plot of the natural logarithm of the transmittance versus time is given along with the peak induced absorption coefficient versus dose. The data indicate color centers with different time dependencies. A log-log plot of the transmission loss in dB/cm versus time indicates a 1/t[sup 1/4] time dependence initially.

  18. F 2 excimer laser (157 nm) radiation modification and surface ablation of PHEMA hydrogels and the effects on bioactivity: Surface attachment and proliferation of human corneal epithelial cells

    NASA Astrophysics Data System (ADS)

    Zainuddin; Chirila, Traian V.; Barnard, Zeke; Watson, Gregory S.; Toh, Chiong; Blakey, Idriss; Whittaker, Andrew K.; Hill, David J. T.

    2011-02-01

    Physical and chemical changes at the surface of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels modified by ablation with an F 2 excimer laser were investigated experimentally. An important observation was that only the outer exposed surface layers of the hydrogel were affected by the exposure to 157 nm radiation. The effect of the surface changes on the tendency of cells to adhere to the PHEMA was also investigated. A 0.5 cm 2 area of the hydrogel surfaces was exposed to laser irradiation at 157 nm to fluences of 0.8 and 4 J cm -2. The changes in surface topography were analysed by light microscopy and atomic force microscopy, while the surface chemistry was characterized by attenuated total reflection infrared and X-ray photoelectron spectroscopies. Cell-interfacial interactions were examined based on the proliferation of human corneal limbal epithelial (HLE) cells cultured on the laser-modified hydrogels, and on the unexposed hydrogels and tissue culture plastic for comparison. It was observed that the surface topography of laser-exposed hydrogels showed rippled patterns with a surface roughness increasing at the higher exposure dose. The changes in surface chemistry were affected not only by an indirect effect of hydrogen and hydroxyl radicals, formed by water photolysis, on the PHEMA, but also by the direct action of laser radiation on PHEMA if the surface layers of the gel become depleted of water. The laser treatment led to a change in the surface characteristics, with a lower concentration of ester side-chains and the formation of new oxygenated species at the surface. The surface also became more hydrophobic. Most importantly, the surface chemistry and the newly created surface topographical features were able to improve the attachment, spreading and growth of HLE cells.

  19. Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

    NASA Technical Reports Server (NTRS)

    Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

    1996-01-01

    This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

  20. 1 W of blue 465-nm radiation generated by frequency doubling of the output of a high-power diode laser in critically phase-matched LiB3O5.

    PubMed

    Woll, D; Beier, B; Boller, K J; Wallenstein, R; Hagberg, M; O'Brien, S

    1999-05-15

    Blue 465-nm radiation is generated by frequency doubling of the output of an InGaAs diode-laser oscillator-amplifier system in critically phase-matched LiB(3)O(5) (LBO). The diode-laser system emitted 4 W of single-frequency 930-nm radiation in a near-diffraction-limited beam (M(2)<1.2) . The laser power is enhanced to values of up to 150 W in a resonant external ring cavity. The LBO crystal is placed at a resonator internal focus. The frequency doubling in the LBO crystal generates blue radiation at 465 nm with a power of 1 W. The spectral width of the blue radiation is less than 3 MHz, and the value of the M(2) beam parameter is less than 1.2. PMID:18073825

  1. Effect of enhanced UV-B radiation on pollen quantity, quality, and seed yield in Brassica rapa (Brassicaceae)

    SciTech Connect

    Demchik, S.M.; Day, T.A.

    1996-05-01

    Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% ({open_quotes}low enhanced{close_quotes}), or 32% ({open_quotes}high enhanced{close_quotes}) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by {approx}50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollen was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from {approx}43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs.

  2. The formation of DNA single-strand breaks and alkali-labile sites in human blood lymphocytes exposed to 365-nm UVA radiation.

    PubMed

    Osipov, Andreyan N; Smetanina, Nadezhda M; Pustovalova, Margarita V; Arkhangelskaya, Ekaterina; Klokov, Dmitry

    2014-08-01

    The potency of UVA radiation, representing 90% of solar UV light reaching the earth's surface, to induce human skin cancer is the subject of continuing controversy. This study was undertaken to investigate the role of reactive oxygen species in DNA damage produced by the exposure of human cells to UVA radiation. This knowledge is important for better understanding of UV-induced carcinogenesis. We measured DNA single-strand breaks and alkali-labile sites in human lymphocytes exposed ex vivo to various doses of 365-nm UV photons compared to X-rays and hydrogen peroxide using the comet assay. We demonstrated that the UVA-induced DNA damage increased in a linear dose-dependent manner. The rate of DNA single-strand breaks and alkali-labile sites after exposure to 1J/cm(2) was similar to the rate induced by exposure to 1 Gy of X-rays or 25 μM hydrogen peroxide. The presence of either the hydroxyl radical scavenger dimethyl sulfoxide or the singlet oxygen quencher sodium azide resulted in a significant reduction in the UVA-induced DNA damage, suggesting a role for these reactive oxygen species in mediating UVA-induced DNA single-strand breaks and alkali-labile sites. We also showed that chromatin relaxation due to hypertonic conditions resulted in increased damage in both untreated and UVA-treated cells. The effect was the most significant in the presence of 0.5M Na(+), implying a role for histone H1. Our data suggest that the majority of DNA single-strand breaks and alkali-labile sites after exposure of human lymphocytes to UVA are produced by reactive oxygen species (the hydroxyl radical and singlet oxygen) and that the state of chromatin may substantially contribute to the outcome of such exposures. PMID:24816295

  3. Size and longevity of seed banks in Antarctica and the influence of ultraviolet-B radiation on survivorship, growth and pigment concentrations of Colobanthus quitensis seedlings.

    PubMed

    Ruhland, C T.; Day, T A.

    2001-04-01

    Populations of Colobanthus quitensis and Deschampsia antarctica, the only two vascular plant species native to Antarctica, are increasing. We performed a seed bank assay to determine the persistence of seeds from intact vegetation/soil cores collected near Palmer Station on the west coast of the Antarctic Peninsula. Vegetation/soil cores were cold stratified at 3 degrees C for >4 years. Subsequent seed bank densities, estimated from seedlings germinated, averaged 847 and 5645 seedlings m(-2) for C. quitensis and D. antarctica, respectively. We also conducted germination trials on C. quitensis seeds collected at our field site and stored for either 120 days or >4 years at 3 degrees C. Germination rates ranged from 6% after 120 days of cold storage to 38% after >4 years of cold storage. These findings show that previous estimates of seed bank densities and germination rates in these species, based on short-term laboratory stratification experiments, may underestimate those found in the field. Stratospheric ozone depletion has lead to increases in ultraviolet-B radiation (UV-B; 280-320 nm) along the Antarctic Peninsula during the austral spring. In a separate experiment we manipulated levels of biologically effective UV-B (UV-B(BE)), over current-year C. quitensis seedlings near Palmer Station on the west coast of the Antarctic Peninsula by placing frames over them that either held filters that absorbed most UV-B(BE) ('reduced UV-B(BE)'), transmitted most UV-B(BE) ('near-ambient UV-B(BE)') or had no filters ('ambient UV-B(BE)'). We monitored seedling survivorship over the course of the growing season (January-March) and growth and pigment concentrations at the end of the season. There were no UV-B(BE) treatment effects on seedling survivorship over the course of the season and overwinter survivorship averaged 12%. However, seedlings growing under near-ambient and ambient UV-B(BE) had 25 and 48% smaller total leaf areas, 7 and 16% fewer leaves and 65 and 82% fewer

  4. Generation of 14  W at 589  nm by frequency doubling of high-power CW linearly polarized Raman fiber laser radiation in MgO:sPPLT crystal.

    PubMed

    Surin, A A; Borisenko, T E; Larin, S V

    2016-06-01

    We introduce an efficient, single-mode, linearly polarized continuous wave (CW) Raman fiber laser (RFL), operating at 1178 nm, with 65 W maximum output power and a narrow linewidth of 0.1 nm. Single-pass second-harmonic generation was demonstrated using a 20 mm long MgO-doped stoichiometric periodically polled lithium tantalate (MgO:sPPLT) crystal pumped by RFL radiation. Output power of 14 W at 589 nm with 22% conversion efficiency was achieved. The possibility of further power scaling is considered, as no crystal degradation was observed at these power levels. PMID:27244435

  5. Generation of high power 200 mW laser radiation at 177.3 nm in KBe2BO3F2 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Bo; Liu, Lijuan; Wang, Xiaoyang; Chen, Chuangtian; Zhang, Xin; Lin, Shujie

    2015-12-01

    With a newly developed diffusion-bonded KBe2BO3F2 prism-coupled device and by temperature stabilization of the device, we have achieved an average power of 200 mW at 177.3 nm through the sixth harmonic generation of a picosecond Nd:YAG laser. This is the highest power at 177.3 nm ever generated in any nonlinear optical crystals. A stable average power of 72.2 mW at 177.3 nm was also obtained with a small fluctuation of 3.2 % over a period of 30 min. Moreover, both the angle and temperature acceptances for the 177.3 nm generation were reported for the first time in this paper.

  6. Photosynthesis, Growth, and Ultraviolet Irradiance Absorbance of Cucurbita pepo L. Leaves Exposed to Ultraviolet-B Radiation (280-315 nm) 1

    PubMed Central

    Sisson, William B.

    1981-01-01

    Net photosynthesis, growth, and ultraviolet (UV) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of UV-B irradiation and a UV-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other UV-B radiation-absorbing compounds from the first leaves increased with time and level of UV-B radiation impinging on leaf surfaces. Although absorbance of UV-B radiation by extracted pigments increased substantially, UV-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective UV-B radiation but not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both UV-B radiation treatments. Repression of photosynthesis by UV-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity. PMID:16661610

  7. Measuring nonlinear reflectance of laser radiation with a wavelength of 2940 nm from silica glass – water and silica glass – ethanol interfaces

    NASA Astrophysics Data System (ADS)

    Gulyamova, E. S.; Il'ichev, N. N.; Pashinin, P. P.; Polyanskii, V. I.; Sidorin, A. V.

    2016-07-01

    We have measured the reflectance of an Er3+ : YAG laser pulse from silica glass – water and silica glass – ethanol interfaces at high (0.9 J cm-2) and low (5 mJ cm-2) energy densities of incident radiation. The nonlinearity of reflectance dynamics is found for high-power radiation during the laser pulse action.

  8. SOLAR RADIATION AND INDUCTION OF DNA DAMAGE, MUTATIONS AND SKIN CANCERS.

    SciTech Connect

    SETLOW,R.B.

    2007-05-10

    An understanding of the effects of sunlight on human skin begins with the effects on DNA and extends to cells, animals and humans. The major DNA photoproducts arising from UVB (280-320 nm) exposures are cyclobutane pyrimidine dimers. If unrepaired, they may kill or mutate cells and result in basal and squamous cell carcinomas. Although UVA (320-400 nm) and visible wavelengths are poorly absorbed by DNA, the existing data indicate clearly that exposures to these wavelengths are responsible, in an animal model, for {approx}95 % of the incidence of cutaneous malignant melanoma (CMM). Six lines of evidence, to be discussed in detail, support the photosensitizing role of melanin in the induction of this cancer. They are: (1) Melanomas induced in backcross hybrids of small tropical fish of the genus Xiphophorus, exposed to wavelengths from 302-547 nm, indicate that {approx}95% of the cancers induced by exposure to sunlight would arise from UVA + visible wavelengths; (2) The action spectrum for inducing melanin-photosensitized oxidant production is very similar to the spectrum for inducing melanoma; (3) Albino whites and blacks, although very sensitive to sunburn and the sunlight induction of non-CMM, have very low incidences of CMM; (4) The incidence of CMM as a function of latitude is very similar to that of UVA, but not UVB; (5) Use of UVA-exposing sun-tanning parlors by the young increases the incidence rate of CMM and (6) Major mutations observed in CMM are not UVB-induced.

  9. Porcine skin damage thresholds for 0.6 to 9.5 cm beam diameters from 1070-nm continuous-wave infrared laser radiation.

    PubMed

    Vincelette, Rebecca; Noojin, Gary D; Harbert, Corey A; Schuster, Kurt J; Shingledecker, Aurora D; Stolarski, Dave; Kumru, Semih S; Oliver, Jeffrey W

    2014-03-01

    There is an increasing use of high-power fiber lasers in manufacturing and telecommunications industries operating in the infrared spectrum between 1000 and 2000 nm, which are advertised to provide as much as 10 kW continuous output power at 1070 nm. Safety standards have traditionally been based on experimental and modeling investigations with scant data available for these wavelengths. A series of studies using 1070-nm infrared lasers to determine the minimum visible lesion damage thresholds in skin using the Yucatan miniature pig (Sus scrofa domestica) for a range of beam diameters (0.6, 1.1, 1.9, 2.4, 4.7, and 9.5 cm) and a range of exposure durations (10 ms to 10 s) is presented. Experimental peak temperatures associated with each damage threshold were measured using thermal imaging. Peak temperatures at damage threshold for the 10-s exposures were ∼10°C lower than those at shorter exposures. The lowest and highest experimental minimum visible lesion damage thresholds were found to have peak radiant exposures of 19 and 432  J/cm2 for the beam diameter-exposure duration pairs of 2.4 cm, 25 ms and 0.6 cm, 10 s, respectively. Thresholds for beam diameters >2.5  cm had a weak to no effect on threshold radiant exposure levels for exposure times ≤0.25  s, but may have a larger effect on thresholds for exposures ≥10  s. PMID:24658776

  10. Radiation hardness evaluations of 65 nm fully depleted silicon on insulator and bulk processes by measuring single event transient pulse widths and single event upset rates

    NASA Astrophysics Data System (ADS)

    Furuta, Jun; Sonezaki, Eiji; Kobayashi, Kazutoshi

    2015-04-01

    We measure single event transient (SET) pulse widths on inverter chains and single event upset (SEU) rates on flip-flops (FFs) fabricated in 65 nm fully depleted silicon on insulator (FD-SOI) and bulk processes. The layout designs of test chips are strictly identical between their processes besides buried oxide (BOX) layers. Experimental results show that neutron-induced SEU and SET rates in the FD-SOI process are 230× and 450× lower than those in the bulk process, respectively.

  11. Effect of Ultraviolet-B (280 to 320 nm) Radiation on Blue-Green Algae (Cyanobacteria), Possible Biological Indicators of Stratospheric Ozone Depletion

    PubMed Central

    Newton, J. W.; Tyler, D. D.; Slodki, M. E.

    1979-01-01

    The effect of ultraviolet-B (280 to 320 nm) irradiation on physiological activities of Anabaena flos-aquae and the water fern Azolla caroliniana has been studied under conditions where lethal effects of irradiation are absent. Nitrogenase activity, measured as acetylene reduction, specifically declined during irradiation with low levels of ultraviolet-B, whereas other physiological activities were unaffected. These findings indicate that measurement of acetylene reduction by cyanobacteria may serve as a specific, sensitive biochemical assay to assess environmental ultraviolet-B effects due to depletion of stratospheric ozone. PMID:16345396

  12. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Generating collimated intense monochromatic beams of soft x radiation from an X-pinch in the wavelength region 0.4-1.0 nm by means of spherical crystal mirrors

    NASA Astrophysics Data System (ADS)

    Faenov, A. Ya; Mingaleev, A. R.; Pikuz, S. A.; Pikuz, T. A.; Romanova, V. M.; Skobelev, I. Yu; Shelkovenko, T. A.

    1993-05-01

    The generation of collimated intense monochromatic beams of soft x radiation in the wavelength interval 0.4-1.0 nm from an X-pinch is reported. This is the first such report. High-quality mica crystals with dimensions of 10 × (30-35) mm were used to form beams with an energy of 2-3.2 μJ, a wavelength spread Δλ/λ=4 · 10-3, and a divergence of 5 · 10-4 rad. The mica crystals were bent into spherical surfaces with a radius of curvature of 10 or 25 cm. The characteristics of the resulting beams are compared with those of the beams from Ta lasers, with a wavelength ~4.5 nm, which are the shortest-wavelength x-ray lasers which have been reported to date. This comparison shows that the beams obtained in the present study are better than those from the Ta laser in terms of several characteristics (divergence, wavelength, and efficiency), while they are worse (but not greatly so) in terms of certain other characteristics (wavelength spread and energy in the pulse. It is thus possible today to solve many practical problems involving the use of collimated intense monochromatic beams of soft x radiation in the wavelength interval 0.25-2.0 nm. These problems can be solved with the help of the x radiation from an X-pinch or from plasmas produced by picosecond or femtosecond table-top lasers and short-focal-length, large-aperture crystal mirrors.

  13. Design of a 10-bit segmented current-steering digital-to-analog converter in CMOS 65 nm technology for the bias of new generation readout chips in high radiation environment

    NASA Astrophysics Data System (ADS)

    De Robertis, G.; Loddo, F.; Mattiazzo, S.; Pacher, L.; Pantano, D.; Tamma, C.

    2016-01-01

    A new pixel front end chip for HL-LHC experiments in CMOS 65nm technology is under development by the CERN RD53 collaboration together with the Chipix65 INFN project. This work describes the design of a 10-bit segmented current-steering Digital-to-Analog Converter (DAC) to provide a programmable bias current to the analog blocks of the circuit. The main requirements are monotonicity, good linearity, limited area consumption and radiation hardness up to 10 MGy. The DAC was prototyped and electrically tested, while irradiation tests will be performed in Autumn 2015.

  14. Interaction of wide band gap single crystals with 248 nm excimer laser radiation. XII. The emission of negative atomic ions from alkali halides

    SciTech Connect

    Kimura, Kenichi; Langford, S. C.; Dickinson, J. T.

    2007-12-01

    Many wide band gap materials yield charged and neutral emissions when exposed to sub-band-gap laser radiation at power densities below the threshold for optical breakdown and plume formation. In this work, we report the observation of negative alkali ions from several alkali halides under comparable conditions. We observe no evidence for negative halogen ions, in spite of the high electron affinities of the halogens. Significantly, the positive and negative alkali ions show a high degree of spatial and temporal overlap. A detailed study of all the relevant particle emissions from potassium chloride (KCl) suggests that K{sup -} is formed by the sequential attachment of two electrons to K{sup +}.

  15. OISL transmitter at 985 nm

    NASA Astrophysics Data System (ADS)

    Larose, Robert; Lauzon, Jocelyn; Mohrdiek, Stefan; Harder, Christoph S.; Changkakoti, Rupak; Park, Peter

    1999-04-01

    For high data rate (greater than 1 Gbps) Optical Inter- Satellite Link (OISL), a compact laser transmitter with high power and good efficiency is required. A trade-off analysis between the technologies such as the mature 840 nm laser diodes, 1064 nm diode-pumped solid state laser and the more recent 1550 nm Erbium Doped Fiber Amplifier (EDFA) is used to find the optical solution. The Si-APDs are preferred for their large detector areas and good noise figures which reduce the tracking requirements and simplify optical design of the receiver. Because of significant amount of power needed to close the link distance up to 7000 km (LEO-LEO), use of 840 nm diodes is limited. In this paper, we present an alternative system based on a system concept denoted as the SLYB (Semiconductor Laser Ytterbium Booster). The SLYB uses a polarization maintaining double-clad ytterbium fiber as a power amplifier. The device houses two semiconductor diodes that are designed to meet telecom reliability: a broad-area 917 nm pump diode and a directly modulated FP laser for signal generation. The output signal is in a linearly polarized state with an extinction ratio of 20 dB. The complete module (15 X 12 X 4.3 cm3) weighs less than 0.9 kg and delivers up to 27 dBm average output power at 985 nm. Designed primarily for direct detection using Si APDs, the transmitter offers a modulation data rate of at least 1.5 Gb/s with a modulation extinction ratio better than 13 dB. Total power consumption is expected to be lower than 8 W by using an uncooled pump laser. Preliminary radiation testing of the fiber indicates output power penalty of 1.5 dB at the end of 10 years in operation. We are presently investigating the fabrication of an improved radiation-hardened Yb-fiber for the final prototype to reduce this penalty. For higher data rate the design can be extended to a Wavelength Division Multiplexing (WDM) scheme adding multiple channels.

  16. In vitro germination characteristics of maize pollen to detect biological activity of environmental pollutants

    SciTech Connect

    Pfahler, P.L.

    1981-01-01

    In vitro pollen germination in maize was evaluated as a method of assessing the mutagenic and physiological effects of environmental pollutants on higher organisms. The extent of mutations was effectively determined by testing sporophytes homozygous for the mutated allele. Physiological effects were effectively determined when chemical agents were added directly into the in vitro medium. Exposure of pollen grains during in vitro germination to ultraviolet radiation in the range 280-320 nm produced little or no change in the germination or rupture percentage but a sharp decrease in pollen tube growth after 1 hr.

  17. Albuquerque, NM, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Albuquerque, NM (35.0N, 106.5W) is situated on the edge of the Rio Grande River and flood plain which cuts across the image. The reddish brown surface of the Albuquerque Basin is a fault depression filled with ancient alluvial fan and lake bed sediments. On the slopes of the Manzano Mountains to the east of Albuquerque, juniper and other timber of the Cibola National Forest can be seen as contrasting dark tones of vegetation.

  18. 308nm excimer laser in dermatology.

    PubMed

    Mehraban, Shadi; Feily, Amir

    2014-01-01

    308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

  19. Radiation

    NASA Video Gallery

    Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

  20. Super ACO FEL oscillation at 300 nm

    NASA Astrophysics Data System (ADS)

    Nutarelli, D.; Garzella, D.; Renault, E.; Nahon, L.; Couprie, M. E.

    2000-05-01

    Some recent improvements, involving both the optical cavity mirrors and the positron beam dynamics in the storage ring, have allowed us to achieve a laser oscillation at 300 nm on the Super ACO Storage Ring FEL. The Super ACO storage ring is operated at 800 MeV which is the nominal energy for the usual synchrotron radiation users, and the highest energy for a storage ring FEL. The lasing at 300 nm could be kept during 2 h per injection, with a stored current ranging between 30 and 60 mA. The FEL characteristics are presented here. The longitudinal stability and the FEL optics behaviour are also discussed.

  1. Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

    DOEpatents

    Marshall, C.D.; Payne, S.A.; Krupke, W.F.

    1996-05-14

    Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

  2. Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

    DOEpatents

    Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

    1996-01-01

    Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

  3. A contribution toward understanding the biospherical significance of Antarctic ozone depletion

    NASA Technical Reports Server (NTRS)

    Lubin, Dan; Mitchell, Greg; Frederick, John E.; Alberts, Amy D.; Booth, C. R.; Lucas, Timothy; Neuschuler, David

    1992-01-01

    The paper presents and compares measurements of biologically active UV radiation made by the NSF scanning spectroradiometer (UV-monitor) at Palmer Station, Antarctica, during the Austral springs of 1988, 1989, and 1990. Column ozone abundance above Palmer Station is computed from these measurements using a multiple wavelength algorithm. Two contrasting action spectra are employed to estimate the biologically relevant dose from the spectral measurements: a standard weighting function for damage to DNA, and a new action spectrum representing the potential for photosynthesis inhibition in Antarctic phytoplankton. The former weights only UV-B wavelengths (280-320 nm) and gives the most weight to wavelengths shorter than 300 nm, while the latter includes large contributions out to 355 nm. Ozone abundances and dose-weighted irradiances provided by the NSF UV-monitor are used to derive the radiation amplification factors for both DNA- and phytoplankton-effective irradiance.

  4. 469nm Fiber Laser Source

    SciTech Connect

    Drobshoff, A; Dawson, J W; Pennington, D M; Payne, S A; Beach, R

    2005-01-20

    We have demonstrated 466mW of 469nm light from a frequency doubled continuous wave fiber laser. The system consisted of a 938nm single frequency laser diode master oscillator, which was amplified in two stages to 5 Watts using cladding pumped Nd{sup 3+} fiber amplifiers and then frequency doubled in a single pass through periodically poled KTP. The 3cm long PPKTP crystal was made by Raicol Crystals Ltd. with a period of 5.9 {micro}m and had a phase match temperature of 47 degrees Centigrade. The beam was focused to a 1/e{sup 2} diameter in the crystal of 29 {micro}m. Overall conversion efficiency was 11% and the results agreed well with standard models. Our 938nm fiber amplifier design minimizes amplified spontaneous emission at 1088nm by employing an optimized core to cladding size ratio. This design allows the 3-level transition to operate at high inversion, thus making it competitive with the 1088nm 4-level transition. We have also carefully chosen the fiber coil diameter to help suppress propagation of wavelengths longer than 938 nm. At 2 Watts, the 938nm laser had an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >10:1).

  5. Flash-lamp pumped Pr:YAP laser operated at wavelengths of 747 nm and 662 nm

    NASA Astrophysics Data System (ADS)

    Fibrich, Martin; Jelínková, Helena; Šulc, Jan; Nejezchleb, Karel; Škoda, Václav

    2009-02-01

    Successful room-temperature generation of Pr:YAP laser radiation at wavelengths of 747 nm and 662 nm was demonstrated. A flash-lamp pumped Pr:YAP laser was operated in free-running pulsed regime at room temperature. Permanent laser action was reached by means of a special UV color glass plate filter placed directly into the laser cavity. The maximum output energy and pulse length reached at wavelengths of 747 nm and 662 nm were 102 mJ, 92 μs and 6.1 mJ, 47.5 μs, respectively. The laser beam parameter M2 ~ 1.5 was measured when the 662 nm wavelength was generated. In the case of 747 nm wavelength generation, M2 ~ 1.2 was reached with a diaphragm inside the resonator. For different pumped energy values, the line shape and linewidth remained stable for both cases.

  6. The interaction of 193 nm excimer laser radiation with single-crystal zinc oxide: Generation of long lived highly excited particles with evidence of Zn Rydberg formation

    SciTech Connect

    Khan, Enamul H.; Langford, S. C.; Dickinson, J. T.; Boatner, L. A.

    2014-08-28

    In past studies, we have observed copious emissions of ionic and atomic Zn from single-crystal ZnO accompanying irradiation of single-crystal ZnO with 193-nm excimer laser irradiation at fluences below the onset of optical breakdown. The Zn{sup +} and ground state Zn° are studied using time-of-flight techniques and are mass selected using a quadrupole mass spectrometer. Simultaneously, we have observed emitted particles that are detectable with a Channeltron electron multiplier but cannot be mass selected. It is a reasonable hypothesis that these particles correspond to a neutral atom or molecule in highly excited long lived states. We provide strong evidence that they correspond to high lying Rydberg states of atomic Zn. We propose a production mechanism involving laser excitation via a two photon resonance excitation of Zn°.

  7. Visible and ultraviolet reflectance characteristics of arctic homeotherms

    NASA Astrophysics Data System (ADS)

    Reynolds, P. S.; Lavigne, D. M.

    1981-12-01

    Reflectance characteristics of the epidermal coverings (hair, feathers) of several white birds and mammals were examined in the visible and ultraviolet regions of the solar spectrum. Non-white phases of the same species, and other non-white animals were examined for comparison. As expected, non-white animals exhibited lower reflectance values than white animals in the visible spectrum. Most species examined demonstrated reduced reflectance in the ultraviolet, reaching minimum values between 290 and 310 nm. In white animals, significant differences were found in the reflectance of UV-A (320 400 nm) and UV-B (280 320 nm) radiation. This accounts for the apparent differences in ultraviolet reflectance among various arctic mammals detected previously with ultraviolet photography. Reflectance patterns in the visible and ultraviolet were not obviously correlated with phylogenetic relationship, nor with the gross structure of hair or feathers.

  8. Nanobumps on silicon created with polystyrene spheres and 248 or 308 nm laser pulses

    SciTech Connect

    Piparia, Reema; Rothe, Erhard W.; Baird, R. J.

    2006-11-27

    Huang et al. [Appl. Phys. Lett. 86, 161911 (2005)] formed arrays of nanobumps on a silicon substrate. They applied a 248 nm laser pulse to a surface monolayer of 1-{mu}m-diameter polystyrene spheres. The authors first replicated their experiment with 248 nm light. But when 308 nm pulses were applied instead, the nanobumps had a different shape and composition. At 248 nm, much of the laser light is absorbed in the polystyrene, which serves to quickly distort, melt, and ablate the sphere. At 308 nm, very little light is absorbed. The nanobumps from 248 nm radiation are organic polymers, while those formed with 308 nm pulses are silicon based.

  9. Photoionization of Nitromethane at 355nm and 266nm

    NASA Astrophysics Data System (ADS)

    Martínez, Denhi; Betancourt, Francisco; Poveda, Juan Carlos; Guerrero, Alfonso; Cisneros, Carmen; Álvarez, Ignacio

    2014-05-01

    Nitromethane is one of the high-yield clean liquid fuels, i.e., thanks to the oxygen contained in nitromethane, much less atmospheric oxygen is burned compared to hydrocarbons such as gasoline, making the nitromethane an important prototypical energetic material, the understanding of its chemistry is relevant in other fields such as atmospheric chemistry or biochemistry. In this work we present the study of photoionization dynamics by multiphoton absorption with 355 nm and 266 nm wavelength photons, using time of flight spectrometry in reflectron mode (R-TOF). Some of the observed ion products appear for both wavelength and other only in one of them; both results were compared with preview observations and new ions were detected. This work is supported by CONACYT grant 165410 and DGAPA-UNAM grants IN-107-912 and IN-102-613.

  10. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  11. Efficient generation of 1096 nm and 1572 nm by simultaneous stimulated Raman scattering and optical parametric oscillation in one KTiOPO4 crystal

    NASA Astrophysics Data System (ADS)

    Huang, H. T.; He, J. L.; Liu, S. D.; Yang, J. F.; Zhang, B. T.; Liu, F. Q.

    2011-04-01

    The simultaneous stimulated Raman scattering (SRS) and optical parametric oscillation (OPO) for the 1064 nm radiation were realized in one KTP crystal for the first time. At an incident diode laser power of 8.6 W, the maximum average output powers at 1096 nm and 1572 nm were 1.1 W and 0.36 W, respectively. The conversion efficiency to Stokes with respect to the incident diode power was as high as 12.8%. The corresponding minimum pulse widths at 1096 nm and 1572 nm were 2.8 and 1.1 ns, respectively.

  12. Comparison of 885 nm pumping and 808 nm pumping in Nd:CNGG laser operating at 1061 nm and 935 nm

    NASA Astrophysics Data System (ADS)

    Shi, Yuxian; Li, Qinan; Zhang, Dongxiang; Feng, Baohua; Zhang, Zhiguo; Zhang, Huaijin; Wang, Jiyang

    2010-07-01

    A Nd:CNGG laser operated at 935 nm and 1061 nm pumped at 885 nm and 808 nm, respectively, is demonstrated. The 885 nm direct pumping scheme shows some advantages over the 808 nm traditional pumping scheme. It includes higher slope efficiency, lower threshold, and better beam quality at high output power. With the direct pumping, the slope efficiency increases by 43% and the threshold decreases by 10% compared with traditional pumping in the Nd:CNGG laser operated at 935 nm. When the Nd:CNGG laser operates at 1061 nm, the direct pumping increases the slope efficiency by 14% with a 20% reduction in the oscillation threshold.

  13. Generation of Thermospheric OI 845 nm Emission by Bowen Fluorescence

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.; Sharpee, B. D.; Cosby, P. C.; Slanger, T. G.

    2006-12-01

    777 and 845 nm emissions from the 3p-3s multiplets of atomic oxygen are commonly observed at non-auroral latitudes in the terrestrial nightglow. By studying the relative strengths of these emissions we can learn something about the mechanisms that produce them and what they can teach us about the atmosphere. Recently [1] we have used intensity-calibrated sky spectra from the Keck telescopes to investigate the relative strengths of a wide range of O-atom Rydberg lines and have confirmed that electron-ion radiative recombination is a primary source of excitation for both the triplet and quintet systems. Following the intensity of the 777 and 845 nm lines during the night, we find that for most of the night the quintet 777 nm line is consistently stronger than the triplet 845 nm line, with a nearly constant intensity ratio I(777)/I(845) near 2.3, although both intensities fall rapidly as the night progresses. However, late in the night the 845 nm intensity levels off, while the 777 nm intensity continues to fall, and the I(777)/I(845) ratio plunges by a factor of 5-10. We interpret these observations as indicating that the O-atom quintet states are still being excited by the same mechanism as earlier in the night, i.e. radiative recombination, but some triplet states are also being excited by an additional mechanism. Such a mechanism has been proposed before [2-6] but not previously observed directly in the terrestrial nightglow. The oxygen triplet 3d-2p transition at 102.576 nm is in close coincidence with the solar hydrogen Lyman-β line at 102.572 nm. Radiative transport in the hydrogen geocorona will deliver Lyman-β intensity into the Earth's shadow and will produce triplet O(3d 3D) high in the atmosphere, even prior to direct solar illumination. The result is observable in a radiative cascade sequence 3d-3p(1129 nm) → 3p- 3s(845 nm) → 3s-2p(130 nm). A similar effect is observed in the H-α emission, which is also excited by Lyman-β absorption. This process

  14. Induction of photolyase activity in wood frog (Rana sylvatica) embryos.

    PubMed

    Smith, M A; Kapron, C M; Berrill, M

    2000-10-01

    Rising ultraviolet-B (UVB, 280-320 nm) radiation has been proposed as a factor which may explain nonnormal amphibian population declines. Accordingly research has been directed toward estimating the photolyase activity of several amphibian species in order to predict a species' resilience to UV damage. Unfortunately, in spite of published research which demonstrated that the activity of one of the principal photorepair enzymes, photolyase, can be induced, these estimates did not address the potential for in vivo induction by environmental factors present in situ. We show here that wood frog (Rana sylvatica) embryos exposed to periods of ambient solar radiation (1) displayed significantly different photolyase activities from embryos exposed to equivalent periods of dark; and (2) were positively correlated with the UVB fluence received in vivo. Such results suggest that previous conclusions regarding the relationship between photorepair and population decline must be reevaluated. Estimating amphibian photorepair is a complicated process, and caution must be exercised when interpreting such data. PMID:11045732

  15. induced by 1,540-nm laser excitation

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Wang, X. F.; He, W. Y.; Bu, Y. Y.; Yan, X. H.

    2014-06-01

    The multi-photon ultraviolet upconversion emission properties and synergistic effect are investigated in BaSr2Y6O12:Er3+ phosphor. The deep-ultraviolet emissions centered at 274, 297 and 324-nm are observed under the 1,540-nm excitation, which results from a seven-, six- and six-photon upconversion process, respectively. A synergistic effect is found, which shows that the red emission intensity under 351- and 1,540-nm dual excitation is 4.7 % time stronger than the sum of red emission intensities under the 351 and 1,540-nm single excitation. This phenomenon is attributed to the 4I13/2 and 4I11/2 levels of Er3+ from non-radiative transition process under the 351-nm excitation are excited again to 4F9/2 level by absorbing 1,540-nm photon in the 351- and 1,540-nm dual-excitation process.

  16. High-efficiency high-brightness diode lasers at 1470 nm/1550 nm for medical and defense applications

    NASA Astrophysics Data System (ADS)

    Gallup, Kendra; Ungar, Jeff; Vaissie, Laurent; Lammert, Rob; Hu, Wentao

    2012-03-01

    Diode lasers in the 1400 nm to 1600 nm regime are used in a variety of applications including pumping Er:YAG lasers, range finding, materials processing, aesthetic medical treatments and surgery. In addition to the compact size, efficiency, and low cost advantages of traditional diode lasers, high power semiconductor lasers in the eye-safe regime are becoming widely used in an effort to minimize the unintended impact of potentially hazardous scattered optical radiation from the laser source, the optical delivery system, or the target itself. In this article we describe the performance of high efficiency high brightness InP laser bars at 1470nm and 1550nm developed at QPC Lasers for applications ranging from surgery to rangefinding.

  17. Sub-180 nm generation with borate crystal

    NASA Astrophysics Data System (ADS)

    Qu, Chen; Yoshimura, Masashi; Tsunoda, Jun; Kaneda, Yushi; Imade, Mamoru; Sasaki, Takatomo; Mori, Yusuke

    2014-10-01

    We demonstrated a new scheme for the generation of 179 nm vacuum-ultraviolet (VUV) light with an all-solid-state laser system. It was achieved by mixing the deep-ultraviolet (DUV) of 198.8 nm and the infrared (IR) of 1799.9 nm. While CsB3O5 (CBO) did not satisfy the phase-matching at around 180 nm, 179 nm output was generated with LiB3O5 (LBO) for the first time. The phase-matching property of LBO at around 180 nm was also investigated. There was small deviation from theoretical curve in the measurement, which is still considered reasonable.

  18. Characterization of an 800 nm SASE FEL at Saturation

    SciTech Connect

    Nuhn, Heinz-Dieter

    2002-11-13

    VISA (Visible to Infrared SASE Amplifier) is an FEL (Free Electron Laser) designed to saturate at a radiation wavelength of 800 nm within a 4-m long, strong focusing undulator. Large gain is achieved by driving the FEL with the 72 MeV, high brightness beam of BNL's Accelerator Test Facility (ATF). We present measurements that demonstrate saturation in addition to the frequency spectrum of the FEL radiation. Energy, gain length and spectral characteristics are compared and shown to agree with simulation and theoretical predictions.

  19. Electro-optically Q-switched dual-wavelength Nd:YLF laser emitting at 1047 nm and 1053 nm

    NASA Astrophysics Data System (ADS)

    Men, Shaojie; Liu, Zhaojun; Cong, Zhenhua; Li, Yongfu; Zhang, Xingyu

    2015-05-01

    A flash-lamp pumped electro-optically Q-switched dual-wavelength Nd:YLF laser is demonstrated. Two Nd:YLF crystals placed in two cavities are employed to generate orthogonally polarized 1047 nm and 1053 nm radiations, respectively. The two cavities are jointed together by a polarizer and share the same electro-optical Q-switch. Two narrow-band pass filters are used to block unexpected oscillations at the hold-off state of the electro-optical Q-switch. In this case, electro-optical Q-switching is able to operate successfully. With pulse synchronization realized, the maximum output energy of 66.2 mJ and 83.9 mJ are obtained for 1047 nm and 1053 nm lasers, respectively. Correspondingly, the minimum pulse width is both 17 ns for 1047 nm and 1053 nm lasers. Sum frequency generation is realized. This demonstrates the potential of this laser in difference-frequency generations to obtain terahertz wave.

  20. 147-nm photolysis of disilane

    SciTech Connect

    Perkins, G.G.A.; Lampe, F.W.

    1980-05-21

    The photodecomposition of Si/sub 2/H/sub 6/ at 147 nm results in the formation of H/sub 2/, SiH/sub 4/, Si/sub 3/H/sub 8/, Si/sub 4/H/sub 10/, Si/sub 5/H/sub 12/, and a solid film of amorphous silicon hydride (a-Si:H). Three primary processes are proposed to account for the results, namely, (a) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 2/ + SiH/sub 3/ + H (phi/sub a/ = 0.61); (b) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 3/SiH + 2H (phi/sub b/ = 0.18); (c) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. Si/sub 2/H/sub 5/ + H (phi/sub c/ = 0.21). The overall quantum yields depend on the pressure but at 1 Torr partial pressure of Si/sub 2/H/sub 6/ are PHI(-Si/sub 2/H/sub 6/) = 4.3 +- 0.2, PHI(SiH/sub 4/) = 1.2 +- 0.4, PHI(Si/sub 3/H/sub 8/) = 0.91 +- 0.08, PHI(Si/sub 4/H/sub 10/) = 0.62 +- 0.03, PHI(Si,wall) = 2.2. Quantum yields for H/sub 2/ formation were not measured. A mechanism is proposed which is shown to be in accord with the experimental facts.

  1. The polarization properties of Fe II 614.9 nm

    NASA Technical Reports Server (NTRS)

    Lites, Bruce W.

    1993-01-01

    The anomalous Zeeman splitting of the Fe II line at 614.9 nm results in four unusual properties of the polarization signature of this line in the presence of magnetic fields: the absence of linear polarization, no magnetooptical effect, the independence of intensity at line center from the inclination of the field, and a depolarizing self-absorption. The origin of these properties is illustrated in terms of the transfer of line radiation in an idealized solar atmosphere.

  2. Baicalin Scavenged Reactive Oxygen Species and Protected Human Keratinocytes Against UVB-induced Cytotoxicity.

    PubMed

    Chang, Wen-Shin; Lin, En-Yuan; Hsu, Shih-Wei; Hu, Pei-Shin; Chuang, Chin-Liang; Liao, Cheng-Hsi; Fu, Chun-Kai; Su, Chung-Hao; Gong, Chi-Li; Hsiao, Chieh-Lun; Bau, DA-Tian; Tsai, Chia-Wen

    Ultraviolet B (UVB), with a wavelength of 280-320 nm, represents one of the most important environmental factors for skin disorders, including sunburn, hyperpigmentation, solar keratosis, solar elastosis and skin cancer. Therefore, protection against excessive UVA-induced damage is useful for prevention of sunburn and other human diseases. Baicalin, a major component of traditional Chinese medicine Scutellaria baicalensis, has been reported to possess antioxidant and cytostatic capacities. In this study, we examined whether baicalin is also capable of protecting human keratinocytes from UVB irradiation. The results showed that baicalin effectively scavenged reactive oxygen species (ROS) elevated within 4 h after UVB radiation and reversed the UVB-suppressed cell viability and UVB-induced apoptosis after 24 h. Our results demonstrated the utility of baicalin to complement the contributions of traditional Chinese medicine in UVB-induced damage to skin and suggested their potential application as pharmaceutical agents in long-term sun-shining injury prevention. PMID:27566079

  3. A nanosecond regenerative Ti:Sapphire amplifier for the simultaneous generation of 940 nm and of 320 nm pulses

    NASA Astrophysics Data System (ADS)

    Talluto, Vincenzo; Blochowicz, Thomas; Walther, Thomas

    2016-05-01

    Narrowband cw radiation at 940 and 960 nm is used to seed a Nd:YAG-pumped regenerative Ti:Sapphire amplifier. A Pockels cell traps a slice of the seed radiation inside the amplifier cavity, generating two synchronized pulses and releasing them after amplification. The total pulse energy is as high as 9 mJ at a pulse duration of 6.5 ns and a Fourier-transform-limited bandwidth. The timing jitter between the two pulses at the two wavelengths is less than ±300 ps. The relative pulse energy can be controlled by the relative seed laser power. Up to 1 mJ pulse energy at 320 nm was achieved by third-harmonic generation.

  4. High-power 467-nm passively locked signal-resonant sum-frequency laser

    SciTech Connect

    Wigley, P.G.; Zhang, Q.; Miesak, E.; Dixon, G.J.

    1995-12-01

    We have generated more than 120 mW of TEM{sub 00} radiation at 467 nm by summing the resonantly enhanced output of an 845-nm GaAlAs tapered semiconductor amplifier with the intracavity field of a 1047-nm diode-pumped Nd:YLF laser, using a KTP crystal. Optical feedback was used to lock the frequency of the tapered amplifier to a cavity resonance. {copyright} {ital 1995 Optical Society of America.}

  5. Absorption spectrum of DNA for wavelengths greater than 300 nm

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.

    1981-06-01

    Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths.

  6. All solid-state sum-frequency generation of 1.12-W continuous-wave laser at 588 nm

    NASA Astrophysics Data System (ADS)

    Lu, Yanfei; Zhang, Xihe; Yao, Zhihai

    2007-06-01

    A new resonator design for doubly resonant continuous-wave (CW) intracavity sum-frequency mixing (SFM) is reported. 1.12 W of coherent radiation at 588 nm is generated by mixing 1062-nm Nd:GdVO4 laser and 1319-nm Nd:YAG laser. The optical-to-optical conversion efficiency is up to 3.7%.

  7. Simultaneous three-wavelength continuous wave laser at 946 nm, 1319 nm and 1064 nm in Nd:YAG

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Zhao, Lianshui; Zhai, Pei; Xia, Jing; Fu, Xihong; Li, Shutao

    2013-01-01

    A continuous-wave (cw) diode-end-pumped Nd:YAG laser that generates simultaneous laser at the wavelengths 946 nm, 1319 nm and 1064 nm is demonstrated. The optimum oscillation condition for the simultaneous three-wavelength operation has been derived. Using the separation of the three output couplers, we obtained the maximum output powers of 0.24 W at 946 nm, 1.07 W at 1319 nm and 1.88 W at 1064 nm at the absorbed pump power of 11.2 W. A total output power of 3.19 W for the three-wavelength was achieved at the absorbed pump power of 11.2 W with optical conversion efficiency of 28.5%.

  8. Diode-pumped Nd:YVO4-Nd:YLF blue laser at 488 nm by intracavity sum-frequency-mixing

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Zhang, X. H.; Li, C. L.; Zhao, Z. M.; Liu, Z. T.

    2010-07-01

    We report a laser architecture to obtain continuous-wave blue radiation at 488 nm. A 808 nm diodepumped the Nd:YVO4 crystal emitting at 914 nm. A part of the pump power was then absorbed by the Nd:YVO4 crystal. The remaining was used to pump the Nd:YLF crystal emitting at 1047 nm. Intracavity sum-frequency mixing at 914 and 1047 nm was then realized in a LBO crystal to reach the blue radiation. We obtained a continuous-wave output power of 514 mW at 488 nm with a pump laser diode emitting 19.6 W at 808 nm.

  9. Measurements of Radiating Flow Fields in the Vacuum Ultraviolet

    NASA Astrophysics Data System (ADS)

    Sheikh, U. A.; Jacobs, C.; Laux, C. O.; Morgan, R. G.; McIntyre, T. J.

    The vacuum ultraviolet (VUV) region of the radiation spectrum spans from 100 nm to 200 nm and is responsible for 30-50 % of the radiative heat flux during peak heating for a lunar return trajectory [1].

  10. Versatile 1 W narrow band 976 nm and 1064 nm light sources

    NASA Astrophysics Data System (ADS)

    Mohrdiek, S.; Pfeiffer, H.-U.; Zibik, E. A.; Sverdlov, B.; Pliska, T.; Lichtenstein, N.

    2011-02-01

    We report on development of novel curved waveguide (CWG) laser devices, where the emission wavelength centered at ~976 nm is stabilized to a 20 dB bandwidth of less than 100 picometer by using fiber Bragg gratings (FBG). Radiation from the curved waveguide laser is coupled using an anamorphic fiber lens into a single mode polarization maintaining fiber containing the FBG, the latter acting as a front reflector. The high power gain chip is based on Oclaro's InGaAs/AlGaAs quantum well laser. Use of the curved waveguide geometry allows to eliminate residual reflections in the optical path of the cavity, which is formed by the rear chip facet and the FBG. It is well known that additional reflections lead to significant deterioration of the spectral and power stability. The devices, assembled in telecom type housings, provide up to 1 W of low-noise and kink-free CW power. In addition pulse operation in nanosecond range is also investigated. The spectral stabilization time to the wavelength of the FBG is limited by the external cavity roundtrip of ~2 ns. A side mode suppression ratio of about 40 dB and higher is achieved for pulsed and CW operation. Results are also presented for a device at 1064 nm. Numerous applications can be envisioned for these devices. For instance devices with high power and ultranarrow spectral bandwidth allow greater flexibility in the choice of parameters for frequency conversion applications. In pulsed mode the device can be used in the special sensing applications where spectral stability is crucial.

  11. Performance of Thin Borosilicate Glass Sheets at 351-nm

    SciTech Connect

    Whitman, P K; Hahn, D; Soules, T; Norton, M; Dixit, S; Donohue, G; Folta, J; Hollingsworth, W; Mainschein-Cline, M

    2004-11-11

    Previously, we reported preliminary results for commercial thin borosilicate glass sheets evaluated for use as a frequently-replaced optic to separate the radiation and contamination produced by the inertial confinement fusion experiments in the National Ignition Facility target chamber from the expensive precision laser optics which focus and shape the 351-nm laser beam. The goal is identification of low cost substrates that can deliver acceptable beam energy and focal spots to the target. The two parameters that dominate the transmitted beam quality are the transmitted wave front error and 351-nm absorption. Commercial materials and fabrication processes have now been identified which meet the beam energy and focus requirements for all of the missions planned for the National Ignition Facility. We present the first data for use of such an optic on the National Ignition Facility laser.

  12. Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Xia, Jing; Liu, Huilong; Pu, Xiaoyun

    2014-10-01

    We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.

  13. INITIAL GAIN MEASUREMENTS OF A 800 NM SASE FEL, VISA.

    SciTech Connect

    FRIGOLA,P.; MUROKH,A.; ET AL; BABZIEN,M.; BEN-ZVI,I.; JOHNSON,E.; MALONE,R.

    2000-08-13

    The VISA (Visible to Infrared SASE Amplifier) FEL is designed to obtain high gain at a radiation wavelength of 800nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6mm and a period of 1.8cm. To obtain large gain the beam and undulator axis have to be aligned to better than 50{micro}m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

  14. Initial Gain Measurements of a 800nm SASE FEL, VISA

    SciTech Connect

    Carr, Roger

    2002-08-14

    The VISA (Visible to Infrared SASE Amplifier) FEL is designed to obtain high gain at a radiation wavelength of 800nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6mm and a period of 1.8cm. To obtain large gain the beam and undulator axis have to be aligned to better than 50{micro}m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

  15. Initial gain measurements of an 800 nm SASE FEL, VISA

    NASA Astrophysics Data System (ADS)

    Frigola, P.; Murokh, A.; Musumeci, P.; Pellegrini, C.; Reiche, S.; Rosenzweig, J.; Tremaine, A.; Babzien, M.; Ben-Zvi, I.; Johnson, E.; Malone, R.; Rakowsky, G.; Skaritka, J.; Wang, X. J.; Van Bibber, K. A.; Bertolini, L.; Hill, J. M.; Le Sage, G. P.; Libkind, M.; Toor, A.; Carr, R.; Cornacchia, M.; Klaisner, L.; Nuhn, H.-D.; Ruland, R.; Nguyen, D. C.

    2001-12-01

    The Visible to Infrared SASE Amplifier (VISA) FEL is designed to obtain high gain at a radiation wavelength of 800 nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72 MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6 mm and a period of 1.8 cm. To obtain large gain the beam and undulator axis have to be aligned to better than 5 μm. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

  16. Sub-10 nm nanopantography

    SciTech Connect

    Tian, Siyuan Donnelly, Vincent M. E-mail: economou@uh.edu; Economou, Demetre J. E-mail: economou@uh.edu; Ruchhoeft, Paul

    2015-11-09

    Nanopantography, a massively parallel nanopatterning method over large areas, was previously shown to be capable of printing 10 nm features in silicon, using an array of 1000 nm-diameter electrostatic lenses, fabricated on the substrate, to focus beamlets of a broad area ion beam on selected regions of the substrate. In the present study, using lens dimensional scaling optimized by computer simulation, and reduction in the ion beam image size and energy dispersion, the resolution of nanopantography was dramatically improved, allowing features as small as 3 nm to be etched into Si.

  17. CMOS downsizing toward sub-10 nm

    NASA Astrophysics Data System (ADS)

    Iwai, Hiroshi

    2004-04-01

    Recently, CMOS downsizing has been accelerated very aggressively in both production and research level, and even transistor operation of a 6 nm gate length p-channel MOSFET was reported in a conference. However, many serious problems are expected for implementing such small-geometry MOSFETs into large scale integrated circuits, and it is still questionable whether we can successfully introduce sub-10 nm CMOS LSIs into the market or not. In this paper, limitation and its possible causes for the downscaling of CMOS towards sub-10 nm are discussed with consideration of past CMOS predictions for the limitation.

  18. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  19. Laser Damage Growth in Fused Silica with Simultaneous 351 nm and 1053 nm irradiation

    SciTech Connect

    Norton, M A; Carr, A V; Carr, C W; Donohue, E E; Feit, M D; Hollingsworth, W G; Liao, Z; Negres, R A; Rubenchik, A M; Wegner, P J

    2008-10-24

    Laser-induced growth of optical damage often determines the useful lifetime of an optic in a high power laser system. We have extended our previous work on growth of laser damage in fused silica with simultaneous 351 nm and 1053 nm laser irradiation by measuring the threshold for growth with various ratios of 351 nm and 1053 nm fluence. Previously we reported that when growth occurs, the growth rate is determined by the total fluence. We now find that the threshold for growth is dependent on both the magnitude of the 351 nm fluence as well as the ratio of the 351 nm fluence to the 1053 nm fluence. Furthermore, the data suggests that under certain conditions the 1053 nm fluence does not contribute to the growth.

  20. Optical extension at the 193-nm wavelength

    NASA Astrophysics Data System (ADS)

    Zandbergen, Peter; McCallum, Martin; Amblard, Gilles R.; Domke, Wolf-Dieter; Smith, Bruce W.; Zavyalova, Lena; Petersen, John S.

    1999-07-01

    Lithography at 193nm is the first optical lithography technique that will be introduced for manufacturing of technology levels. where the required dimensions are smaller than the actual wavelength. This paper explores several techniques to extend 193nm to low k1 lithography. Most attention is given to binary mask solution in at 130nm dimensions, where k1 is 0.4. Various strong and Gaussian quadrupole illuminators were designed, manufactured and tested for this application. Strong quadrupoles show that largest DOF improvements. The drawback however, is that these strong quadrupoles are very duty cycle and dimensions specific, resulting in large proximity biases between different duty cycles. Due to their design, Gaussian quadrupoles sample much wider frequency ranges, resulting in less duty cycles specific DOF improvements and less proximity basis. At sub-130nm dimensions, strong phase shift masks provide significant latitude improvements, when compared to binary masks with quadrupole illumination. However, differences in dose to size for different duty cycles were up to 25 percent. For definition of contact holes, linewidth biasing through silylation, a key feature of the CARL bi-layer resist approach, demonstrated significant DOF latitude improvements compared to SLR at 140nm and 160nm contact holes.

  1. The Double-ended 750 nm and 532 nm Laser Output from PPLN-FWM

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Yu-Xiang; Yao, Jian-Quan; Guo, Ling; Wang, Zhuo; Han, Sha-Sha; Zhang, Cui-Ying; Zhong, Kai

    2013-06-01

    We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things. A kind of optical maser is developed, in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd3+ :YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser. The laser outputs come from both left and right terminals. In the right branch, the laser goes into the right cycle polarization LinNbO3 (PPLN) crystal through the right coupler, produces the optical parametric oscillation and forms the signal light λ1 (1500 nm), the idle frequency light λ2 (3660.55 nm), and the second-harmonic of the signal light λ3 (750 nm). These three kinds of light and the pump light λ4 together form the frequency matching and the quasi-phase matching, then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm. Meanwhile, in the left branch, the laser goes into the left PPLN crystal through the left coupler, engenders frequency doubling and forms the light at wavelength 532 nm. That is to say, the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals, which is workable.

  2. Coherent quasi-CW 153-nm light source at high repetition rate

    NASA Astrophysics Data System (ADS)

    Nomura, Yutaka; Ito, Yoshiaki; Ozawa, Akira; Wang, Xiaoyang; Chen, Chuangtian; Shin, Shik; Watanabe, Shuntaro; Kobayashi, Yohei

    2012-02-01

    We present a quasi-cw laser in vacuum ultraviolet region at megahertz repetition rate. The narrowband pulses generated from an ytterbium-fiber laser system at 33 MHz repetition rate at the central wavelength of 1074 nm is frequency-converted by successive stages of LBO crystals and KBBF crystals. The generated radiation at 153 nm has the shortest wavelength achieved through phase-matched frequency conversion processes in nonlinear optical crystals to our knowledge.

  3. Chromosomes without a 30-nm chromatin fiber

    PubMed Central

    Joti, Yasumasa; Hikima, Takaaki; Nishino, Yoshinori; Kamada, Fukumi; Hihara, Saera; Takata, Hideaki; Ishikawa, Tetsuya; Maeshima, Kazuhiro

    2012-01-01

    How is a long strand of genomic DNA packaged into a mitotic chromosome or nucleus? The nucleosome fiber (beads-on-a-string), in which DNA is wrapped around core histones, has long been assumed to be folded into a 30-nm chromatin fiber, and a further helically folded larger fiber. However, when frozen hydrated human mitotic cells were observed using cryoelectron microscopy, no higher-order structures that included 30-nm chromatin fibers were found. To investigate the bulk structure of mitotic chromosomes further, we performed small-angle X-ray scattering (SAXS), which can detect periodic structures in noncrystalline materials in solution. The results were striking: no structural feature larger than 11 nm was detected, even at a chromosome-diameter scale (~1 μm). We also found a similar scattering pattern in interphase nuclei of HeLa cells in the range up to ~275 nm. Our findings suggest a common structural feature in interphase and mitotic chromatins: compact and irregular folding of nucleosome fibers occurs without a 30-nm chromatin structure. PMID:22825571

  4. 810nm, 980nm, 1470nm and 1950nm diode laser comparison: a preliminary "ex vivo" study on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Sozzi, Michele; Selleri, Stefano; Vescovi, Paolo; Cucinotta, Annamaria

    2015-02-01

    The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of "tissue respect", have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this "ex vivo" study, probably due to their greatest affinity to water.

  5. A 4 to 0.1 nm FEL Based on the SLAC Linac

    SciTech Connect

    Pellegrini, C.; /UCLA

    2012-06-05

    The author show that using existing electron gun technology and a high energy linac like the one at SLAC, it is possible to build a Free Electron Laser operating around the 4 nm water window. A modest improvement in the gun performance would further allow to extend the FEL to the 0.1 nm region. Such a system would produce radiation with a brightness many order of magnitude above that of any synchrotron radiation source, existing or under construction, with laser power in the multigawatt region and subpicosecond pulse length.

  6. Diode laser (980nm) cartilage reshaping

    NASA Astrophysics Data System (ADS)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  7. Sum-frequency generation of continuous-wave light at 194 nm.

    PubMed

    Berkeland, D J; Cruz, F C; Bergquist, J C

    1997-06-20

    Over 2 mW of continuous-wave tunable 194-nm light is produced by sum-frequency mixing approximately 500 mW of 792-nm and 500 mW of 257-nm radiation in beta-barium borate (BBO). The powers in both fundamental beams are enhanced in separate ring cavities whose optical paths overlap in the Brewster-cut BBO crystal. Due to the higher circulating fundamental powers, the sum-frequency-generated power is nearly 2 orders of magnitude greater than previously reported values. PMID:18253443

  8. Compact 498-nm light source based on intracavity sum-frequency Nd:GGG laser

    NASA Astrophysics Data System (ADS)

    Wang, A. G.; Li, Y. L.

    2011-08-01

    We report a coherent cyan radiation at 498 nm by intracavity sum-frequency generation of the 937 and 1062 nm laser-lines of the Nd:GGG crystal. With a diode pump power of 18.2 W, the maximum cyan output power of 186 mW is obtained. The beam quality M2 value is 1.22 in the horizontal plane. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is first work on intracavity sum-frequency generation of a diode pumped Nd:GGG laser at 498 nm.

  9. 1550-nm wavelength-tunable HCG VCSELs

    NASA Astrophysics Data System (ADS)

    Chase, Christopher; Rao, Yi; Huang, Michael; Chang-Hasnain, Connie

    2014-02-01

    We demonstrate wavelength-tunable VCSELs using high contrast gratings (HCGs) as the top output mirror on VCSELs, operating at 1550 nm. Tunable HCG VCSELs with a ~25 nm mechanical tuning range as well as VCSELs with 2 mW output power were realized. Error-free operation of an optical link using directly-modulated tunable HCG VCSELs transmitting at 1.25 Gbps over 18 channels spaced by 100 GHz and transmitted over 20 km of single mode fiber is demonstrated, showing the suitability of the HCG tunable VCSEL as a low cost source for WDM communications systems.

  10. Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

    2015-10-01

    The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

  11. 494 nm blue laser based on sum-frequency mixing of diode pumped Nd3+ lasers

    NASA Astrophysics Data System (ADS)

    Zou, J.; Wang, L. R.

    2012-02-01

    We report for the first time a continuous-wave (CW) blue radiation at 494 nm by intracavity sumfrequency generation of 912 nm Nd:GdVO4 laser and 1079 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 494 nm blue laser was obtained by 912 and 1079 nm intra-cavity sum-frequency mixing, and output power of 179 mW was demonstrated. At the output power level of 179 mW, the output power stability is better than 3.5% and laser beam quality M 2 factor is 1.21.

  12. An anti-reflection coating for use with PMMA at 193 nm

    NASA Technical Reports Server (NTRS)

    Yen, Anthony; Smith, Henry I.; Schattenburg, M. L.; Taylor, Gary N.

    1992-01-01

    An antireflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for ArF excimer laser lithography (193 nm) was formulated. It consists of PMMA and a bis-azide, 4.4-prime-diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin-coating and development. The effectiveness of the ARC was demonstrated by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (about 50 nm linewidth) that are almost entirely free of an orthogonal standing wave.

  13. An anti-reflection coating for use with PMMA at 193 nm

    NASA Astrophysics Data System (ADS)

    Yen, Anthony; Smith, Henry I.; Schattenburg, M. L.; Taylor, Gary N.

    1992-02-01

    An antireflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for ArF excimer laser lithography (193 nm) was formulated. It consists of PMMA and a bis-azide, 4.4-prime-diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin-coating and development. The effectiveness of the ARC was demonstrated by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (about 50 nm linewidth) that are almost entirely free of an orthogonal standing wave.

  14. Negative-tone 193-nm resists

    NASA Astrophysics Data System (ADS)

    Cho, Sungseo; Vander Heyden, Anthony; Byers, Jeff D.; Willson, C. Grant

    2000-06-01

    A great deal of progress has been made in the design of single layer positive tone resists for 193 nm lithography. Commercial samples of such materials are now available from many vendors. The patterning of certain levels of devices profits from the use of negative tone resists. There have been several reports of work directed toward the design of negative tones resists for 193 nm exposure but, none have performed as well as the positive tone systems. Polymers with alicyclic structures in the backbone have emerged as excellent platforms from which to design positive tone resists for 193 nm exposure. We now report the adaptation of this class of polymers to the design of high performance negative tone 193 nm resists. New systems have been prepared that are based on a polarity switch mechanism for modulation of the dissolution rate. The systems are based on a polar, alicyclic polymer backbone that includes a monomer bearing a glycol pendant group that undergoes the acid catalyzed pinacol rearrangement upon exposure and bake to produce the corresponding less polar ketone. This monomer was copolymerized with maleic anhydride and a norbornene bearing a bis-trifluoromethylcarbinol. The rearrangement of the copolymer was monitored by FT-IR as a function of temperature. The synthesis of the norbornene monomers will be presented together with characterization of copolymers of these monomers with maleic anhydride. The lithographic performance of the new resist system will also be presented.

  15. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

  16. VizieR Online Data Catalog: Thorium spectrum from 250nm to 5500nm (Redman+, 2014)

    NASA Astrophysics Data System (ADS)

    Redman, S. L.; Nave, G.; Sansonetti, C. J.

    2014-04-01

    We observed the spectrum of a commercial sealed Th/Ar HCL running at 25mA for almost 15hr starting on 2011 November 2. The region of observation was limited to between 8500/cm and 28000/cm (360nm and 1200nm) by the sensitivity of the silicon photodiode detector. (5 data files).

  17. Generation of femtosecond laser pulses tunable from 380 nm to 465 nm via cascaded nonlinear optical mixing in a noncollinear optical parametric amplifier with a type-I phase matched BBO crystal.

    PubMed

    Lee, Chao-Kuei; Zhang, Jing-Yuan; Huang, J; Pan, Ci-Ling

    2003-07-14

    We report the generation of tunable femtosecond pulses from 380nm to 465nm near the degenerate point of a 405-nm pumped type-I BBO noncollinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a fixed seeding angle, the generated SFG and SHG covers from 385 nm to 465-nm. With a pumping energy of 75 J at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%. PMID:19466049

  18. Total dose responses and reliability issues of 65 nm NMOSFETs

    NASA Astrophysics Data System (ADS)

    Dezhao, Yu; Qiwen, Zheng; Jiangwei, Cui; Hang, Zhou; Xuefeng, Yu; Qi, Guo

    2016-06-01

    In this paper, total dose responses and reliability issues of MOSFETs fabricated by 65 nm CMOS technology were examined. “Radiation-induced narrow channel effect” is observed in a narrow channel device. Similar to total dose responses of NMOSFETs, narrow channel NMOSFEs have larger hot-carrier-induced degradation than wide channel devices. Step Time-Dependent Dielectric Breakdown (TDDB) stresses are applied, and narrow channel devices have higher breakdown voltage than wide channel devices, which agree with “weakest link” theory of TDDB. Experimental results show that linear current, transconductance, saturated drain current and subthreshold swing are superposed degenerated by total dose irradiation and reliability issues, which may result in different lifetime from that considering total dose irradiation reliability issues separately. Project supported by “Light of West China” Program of CAS (No. XBBS201219).

  19. Results of the VISA SASE FEL Experiment at 840 nm

    SciTech Connect

    Murokh, A.

    2004-01-20

    VISA (Visible to Infrared SASE Amplifier) is a high-gain self-amplified spontaneous emission FEL, which achieved saturation at 840 nm within a single-pass 4-m undulator. A gain length shorter than 18 cm has been obtained, yielding the gain of 2 x 10{sup 8} at saturation. The FEL performance, including spectral, angular, and statistical properties of SASE radiation, has been characterized for different electron beam conditions. The results are compared to 3-D SASE FEL theory and start-to-end numerical simulations of the entire injector, transport, and FEL system. Detailed agreement between simulations and experimental results is obtained over the wide range of the electron beam parameters.

  20. Results of the VISA SASE FEL experiment at 840 nm

    NASA Astrophysics Data System (ADS)

    Murokh, A.; Agustsson, R.; Babzien, M.; Ben-Zvi, I.; Bertolini, L.; van Bibber, K.; Carr, R.; Cornacchia, M.; Frigola, P.; Hill, J.; Johnson, E.; Klaisner, L.; Le Sage, G.; Libkind, M.; Malone, R.; Nuhn, H.-D.; Pellegrini, C.; Reiche, S.; Rakowsky, G.; Rosenzweig, J.; Ruland, R.; Skaritka, J.; Toor, A.; Tremaine, A.; Wang, X.; Yakimenko, V.

    2003-07-01

    VISA (Visible to Infrared SASE Amplifier) is a high-gain self-amplified spontaneous emission FEL, which achieved saturation at 840 nm within a single-pass 4-m undulator. A gain length shorter than 18 cm has been obtained, yielding the gain of 2×10 8 at saturation. The FEL performance, including spectral, angular, and statistical properties of SASE radiation, has been characterized for different electron beam conditions. The results are compared to 3-D SASE FEL theory and start-to-end numerical simulations of the entire injector, transport, and FEL system. Detailed agreement between simulations and experimental results is obtained over the wide range of the electron beam parameters.

  1. External-cavity frequency doubling of a 5-W 756-nm injection-locked Ti:sapphire laser.

    PubMed

    Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

    2008-03-31

    We have developed a 5-W 756-nm injection-locked Ti:sapphire laser and frequency-doubled it in an external enhancement cavity for the generation of watt-level 378-nm single-frequency radiation, which is essential for isotope-selective optical pumping of thallium atoms. With a lithium triborate (LBO) crystal in the enhancement cavity, 1.1 W at 378 nm was coupled out from the cavity. Such results are to our knowledge the highest powers of continuous-wave single-frequency radiation generated from a Ti:sapphire laser and its frequency doubling. PMID:18542585

  2. Laser damage database at 1064 nm

    SciTech Connect

    Rainer, F.; Gonzales, R.P.; Morgan, A.J.

    1990-03-01

    In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs.

  3. Sunlight induced 685 nm fluorescence imagery

    NASA Technical Reports Server (NTRS)

    Kim, Hongsuk H.; Van Der Piepen, Heinz

    1986-01-01

    The capability of a new fluorescence method is evaluated using data from an aircraft fluorescence experiment conducted on the Elbe River on August 10-14, 1981. The technique measures chlorophyll concentrations by monitoring sunlight-induced fluorescence at 685 nm. Upwelling radiance spectra and vertical profiles of upwelling radiances are presented and analyzed. The image-processing algorithm used to retrieve fluorescence signals from raw data is described.

  4. Binary 193nm photomasks aging phenomenon study

    NASA Astrophysics Data System (ADS)

    Dufaye, Félix; Sartelli, Luca; Pogliani, Carlo; Gough, Stuart; Sundermann, Frank; Miyashita, Hiroyuki; Hidenori, Yoshioka; Charras, Nathalie; Brochard, Christophe; Thivolle, Nicolas

    2011-05-01

    193nm binary photomasks are still used in the semiconductor industry for the lithography of some critical layers for the nodes 90nm and 65nm, with high volumes and over long period. These 193nm binary masks seem to be well-known but recent studies have shown surprising degrading effects, like Electric Field induced chromium Migration (EFM) [1] or chromium migration [2] [3] . Phase shift Masks (PSM) or Opaque MoSi On Glass (OMOG) might not be concerned by these effects [4] [6] under certain conditions. In this paper, we will focus our study on two layers gate and metal lines. We will detail the effects of mask aging, with SEM top view pictures revealing a degraded chromium edge profile and TEM chemical analyses demonstrating the growth of a chromium oxide on the sidewall. SEMCD measurements after volume production indicated a modified CD with respect to initial CD data after manufacture. A regression analysis of these CD measurements shows a radial effect, a die effect and an isolated-dense effect. Mask cleaning effectiveness has also been investigated, with sulphate or ozone cleans, to recover the mask quality in terms of CD. In complement, wafer intrafield CD measurements have been performed on the most sensitive structure to monitor the evolution of the aging effect on mask CD uniformity. Mask CD drift have been correlated with exposure dose drift and isolated-dense bias CD drift on wafers. In the end, we will try to propose a physical explanation of this aging phenomenon and a solution to prevent from it occurring.

  5. Efficient emission at 1908 nm in a diode-pumped Tm:YLF laser

    SciTech Connect

    Zakharov, N G; Antipov, Oleg L; Savikin, A P; Sharkov, V V; Eremeikin, O N; Frolov, Yu N; Mishchenko, G M; Velikanov, S D

    2009-05-31

    Emission parameters at 1908 nm in a longitudinally-diode-pumped Tm:YLF laser are studied. The laser parameters are optimised to obtain the maximal power of high-quality cw radiation. The output power of {approx}27 W is obtained at the slope efficiency of {approx}50% and total optical pump conversion efficiency of {approx}41%. (lasers and amplifiers)

  6. AIMS mask qualification for 32nm node

    NASA Astrophysics Data System (ADS)

    Richter, Rigo; Thaler, Thomas; Seitz, Holger; Stroessner, Ulrich; Scheruebl, Thomas

    2009-10-01

    Moving forward to 32nm node and below optical lithography using 193nm is faced with complex requirements to be solved. Mask makers are forced to address both Double Patterning Techniques and Computational Lithography approaches such as Source Mask Optimizations and Inverse Lithography. Additionally, lithography at low k1 values increases the challenges for mask repair as well as for repair verification and review by AIMSTM. Higher CD repeatability, more flexibility in the illumination settings as well as significantly improved image performance must be added when developing the next generation mask qualification equipment. This paper reports latest measurement results verifying the appropriateness of the latest member of AIMSTM measurement tools - the AIMSTM 32-193i. We analyze CD repeatability measurements on lines and spaces pattern. The influence of the improved optical performance and newly introduced interferometer stage will be verified. This paper highlights both the new Double Patterning functionality emulating double patterning processes and the influence of its critical parameters such as overlay errors and resist impact. Beneficial advanced illumination schemes emulating scanner illumination document the AIMSTM 32-193i to meet mask maker community's requirements for the 32nm node.

  7. Effect of UVB 311 nm irradiation on normal human skin.

    PubMed

    Viac, J; Goujon, C; Misery, L; Staniek, V; Faure, M; Schmitt, D; Claudy, A

    1997-06-01

    Ultraviolet radiation B (UVB) on the skin induces erythema, inflammation and modifications of the immune system. These changes have been reported after excessive short-term or long-term exposure to broad spectrum UVB. In this study, we examined the effects of local repetitive UVB irradiation of 311 nm wavelength on the skin of seven young volunteers. Skin biopsies were taken before and after UVB irradiation, and we immunohistochemically analyzed the expression of CD1a and HLA-DR antigens of Langerhans cells (LC), the possible infiltration of dermis/epidermis by CD11b macrophages, the modifications or the induction of intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1) involved in the binding of leukocytes to the endothelial surface and the development of perivascular infiltrates of LFA-1+ mononuclear cells. We also determined the expression of substance P receptors (SPR) using biotinylated substance P (SPB). Exposure of UVB 311 nm induced a drastic reduction of CD1a+ cells and a moderate increase of HLA-DR+ dendritic cells in the epidermis without infiltration by CD11b macrophages. An increase of the binding of SPB to upper layer epidermal cells was noted in five of seven biopsies. In the dermis, vessel-associated ICAM-1 expression increased and an induction of E-selectin occurred on nearly 20 to 40% of endothelial cells, but VCAM-1 expression remained undetectable. The percentage of LFA-1+ cells did not change significantly after irradiation. These observations may be compatible with a selective role of UVB 311 nm on the skin immune response. PMID:9372527

  8. Status and initial commissioning of a high gain 800 nm SASE FEL

    NASA Astrophysics Data System (ADS)

    Tremaine, A.; Frigola, P.; Murokh, A.; Musumeci, P.; Pellegrini, C.; Rosenzweig, J.; Babzien, M.; Ben-Zvi, I.; Johnson, E.; Malone, R.; Rakowsky, G.; Skaritka, J.; Wang, X. J.; Yu, L. H.; Van Bibber, K. A.; Hill, J. M.; Le Sage, G. P.; Carr, R.; Cornacchia, M.; Nuhn, H.-D.; Ruland, R.; Nguyen, D. C.

    2000-05-01

    We describe the status and initial commissioning of the Visible to Infrared SASE Amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation.

  9. Frequency control of a 1163 nm singly resonant OPO based on MgO:PPLN.

    PubMed

    Gross, P; Lindsay, I D; Lee, C J; Nittmann, M; Bauer, T; Bartschke, J; Warring, U; Fischer, A; Kellerbauer, A; Boller, K-J

    2010-03-15

    We report the realization of a singly resonant optical parametric oscillator (SRO) that is designed to provide narrow-bandwidth, continuously tunable radiation at a wavelength of 1163 nm for optical cooling of osmium ions. The SRO is based on periodically poled, magnesium-oxide-doped lithium niobate and pumped at 532 nm. The output coupling of the resonant idler wave is adjusted to yield up to 400 mW of 1163 nm radiation, with a bandwidth of a few megahertz. For continuous frequency tuning of the idler wave, the SRO is equipped with an intracavity etalon, and the cavity length is controlled with a piezo-actuated mirror synchronized to the etalon angle. PMID:20237610

  10. Sub-50nm extreme ultraviolet holographic imaging

    NASA Astrophysics Data System (ADS)

    Wachulak, P. W.; Marconi, M. C.; Bartels, R. A.; Menoni, C. S.; Rocca, J. J.

    2009-05-01

    Imaging tools for nanoscicence involving sub-100-nm scale objects have been dominated by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and electron microscopy (SEM, TEM). These imaging techniques have contributed substantially to the development of nanoscience, providing a very powerful diagnostic tool capable of obtaining images with atomic resolution or as a subsidiary mechanism to arrange or modify surfaces also at the atomic scale [1,2]. However, some important problems have persisted traditional nanoscale imaging techniques. For example when scanning a nanometer size object that is not attached rigidly to a surface the interaction with the tip significantly perturbs the specimen degrading or eventually precluding the image acquisition. Electron microscopy often requires surface preparation, consisting of metallization of the sample to avoid surface charging. Additionally the metallization of the sample may alter its characteristics and also limits the resolution. In both cases, if the sample is large (millimeters in size) due to the limited field of view, the image obtained with these conventional methods is only representative of a very small portion of the object. Wavelength-limited holographic imaging using carbon nanotubes as the test object with a table-top extreme ultraviolet (EUV) laser operating at 46.9 nm will be discussed. The resolution achieved in this imaging is evaluated with a rigorous correlation image analysis and confirmed with the conventional knife-edge test. The nano-holography presented requires no optics or critical beam alignment; thus the hologram recording scheme is very simple and does not need special sample preparation. In holography, image contrast requires absorption to provide scattering by the illuminating beam. The EUV laser wavelength employed in this experiment (46.9nm) is advantageous because carbon based materials typically exhibit very small attenuation lengths, around 25 nm. The high absorption of

  11. Scaling of laser-induced contamination growth at 266nm and 355nm

    NASA Astrophysics Data System (ADS)

    Ließmann, M.; Jensen, L.; Balasa, I.; Hunnekuhl, M.; Büttner, A.; Weßels, P.; Neumann, J.; Ristau, D.

    2015-11-01

    The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.

  12. An 885-nm Direct Pumped Nd:CNGG 1061 nm Q-Switched Laser

    NASA Astrophysics Data System (ADS)

    Li, Qi-Nan; Zhang, Tao; Feng, Bao-Hua; Zhang, Zhi-Guo; Zhang, Huai-Jin; Wang, Ji-Yang

    2014-07-01

    The 885 nm direct pumping method, directly into the 4F3/2 emitting level of Nd3+ ion, is used to a Nd:CNGG crystal to product passive Q-switched 1061 nm laser pulses, for the first time to the best of our knowledge. A maximum average output power of 1.16 W for 1061 nm Q-switched pulses and a repetition rate of 12.54 kHz are obtained. The pulse width is measured to be 24 ns and the peak power is 3.843 kW. A high-quality fundamental transverse mode can be observed owing to the reduction of the thermal effect for Nd:CNGG crystal by 885 nm direct pumping.

  13. Dosimetric analysis for low-level laser therapy (LLLT) of the human inner ear at 593 nm and 633 nm

    NASA Astrophysics Data System (ADS)

    Beyer, Wolfgang; Baumgartner, Reinhold; Tauber, Stefan

    1998-12-01

    The administration of low-level-laserlight for irradiation of the inner ear could represented a new therapeutic model for complex diseases of the inner ear. However, successful therapy requires a well-defined light dosimetry based on a dosimetric analysis of the human cochlea that represents a complex anatomy. The light distribution inside the cochlear windings, produced by an irradiation of the tympanic membrane, was quantitatively measured ex vivo for HeNe laser wavelengths of 593 nm and 633 nm. To obtain the space irradiance within an intact cochlea a correction factor of about 6 has been determined by Monte Carlo calculations. It follows from 3 contributions, first the backscattering of light in the bony parts removed during the preparation procedure of the specimen, second the change of index of refraction from the bony parts to air and third some geometrical factors due to the angular distribution of the radiation. The transmission of light across the tympanic cavity and the promontory depends strongly on the wavelength. Due to the observed spatial intensity variations of a factor 10 and more inside the cochlear windings the optimum external light dose has to be chosen with regard to the tonotopy of the ear.

  14. Ultraviolet-induced photodegradation of cucumber (Cucumis sativus L. ) microsomal and soluble protein tryptophanyl residues in vitro

    SciTech Connect

    Caldwell, C.R. )

    1993-03-01

    The in vitro effects of ultraviolet B (280--320 nm) radiation on microsomal membrane proteins and partially purified ribulose bisphosphate carboxylase (Rubisco) from cucumber (Cucumis sativus L.) was investigated by measuring the direct photolytic reduction of tryptophan fluorescence and the formation of fluorescent photooxidation products. Exposure of microsomes and Rubisco to monochromatic 300-nm radiation resulted in the loss of intrinsic tryptophan fluorescence and the production of blue-emitting fluorophores. The major product of tryptophan photolysis was tentatively identified as N-formylkynurenine (N-FK). Even though the rates of tryptophan photodegradation and N-FK formation were similar, the amount of blue fluorescence produced was significantly higher in the microsomes relative to Rubisco. Studies with various free radical scavengers and other modifiers indicated that tryptophan photodegradation requires oxygen species. The optimum wavelengths for loss of tryptophan fluorescence were 290 nm for the microsomes and 280 nm for Rubisco. The temperature dependence of tryptophan fluorescence and rate of tryptophan photodegradation indicated an alteration in the cucumber microsomal membranes at about 24[degrees]C, which influenced protein structure and tryptophan photosensitivity. 29 refs., 6 figs., 1 tab.

  15. 1064 nm Nd:YAG laser intracavity pumped at 946 nm and sum-frequency mixing for an emission at 501 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Jin, G. Y.; Wang, J. G.; Yin, X. D.; Zhang, A. F.

    2010-05-01

    We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm.

  16. Quantitative photoabsorption and fluorescence spectroscopy of benzene, naphthalene, and some derivatives at 106-295 nm

    NASA Technical Reports Server (NTRS)

    Suto, Masako; Wang, Xiuyan; Shan, Jun; Lee, L. C.

    1992-01-01

    Photoabsorption and fluorescence cross sections of benzene, (o-, m-, p-) xylenes, naphthalene, 1-methylnaphthalene, and 2-ethylnaphthalene in the gas phase are measured at 106-295 nm using synchrotron radiation as a light source. Fluorescences are observed from the photoexcitation of benzene and xylenes at 230-280 nm and from naphthalene and its derivatives at 190-295 nm. The absolute fluorescence cross section is determined by calibration with respect to the emission intensity of the NO(A-X) system, for which the fluorescence quantum yield is equal to 1. To cross-check the current calibration method, the quantum yield of the SO2(C-X) system at 220-230 nm was measured since it is about equal to 1. The current quantum-yield data are compared with previously published values measured by different methods.

  17. Mode-locked Nd:YAG laser with output at 1052, 1061, 1064, and 1074 nm

    SciTech Connect

    Badalian, A.A.; Sapondzhian, S.O.; Sarkisian, D.G.; Torosian, G.A.

    1985-10-01

    The picosecond Nd:YAG laser with an output radiation at 1064 nm is currently widely used. However, in connection with many applications, picosecond pulses at other wavelengths are also needed. The present study is, therefore, concerned with the development of a picosecond laser which provides pulses at 1052, 1061.5, and 1073.7 nm. Lasing at 1052, 1061.5, 1064, and 1073.7 nm was achieved by varying the angle between the resonator axis and the normal to the etalon by four degrees. Attention is given to the measurement of the lengths of the ultrashort pulses, and the transverse distribution of the energy in the second harmonic for the wavelength 1052 nm. The discretely tunable picosecond Nd:YAG laser described appears to be a promising tool for many research applications. 9 references.

  18. 157 nm F2-laser writing of silica optical waveguides in silicone rubber

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R.

    2005-10-01

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nmF2-laser radiation. The 2 mm thick silicone was exposed through a thin (˜0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 µm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of ˜6 dB/cm is reported at the 1550 nm wavelength.

  19. 157 nm F2-laser writing of silica optical waveguides in silicone rubber.

    PubMed

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R

    2005-10-15

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nm F2-laser radiation. The 2 mm thick silicone was exposed through a thin (approximately 0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 microm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of approximately 6 dB/cm is reported at the 1550 nm wavelength. PMID:16252756

  20. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  1. Fluorinated dissolution inhibitors for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Hamad, Alyssandrea H.; Bae, Young C.; Liu, Xiang-Qian; Ober, Christopher K.; Houlihan, Francis M.; Dabbagh, Gary; Novembre, Anthony E.

    2002-07-01

    Fluorinated dissolution inhibitors (DIs) for 157 nm lithography were designed and synthesized as part of an ongoing study on the structure/property relationships of photoresist additives. The problem of volatilization of small DI candidates was observed from matrices such as poly(methyl methacrylate) (PMMA) and poly(hexafluorohydroxy-isopropyl styrene) (PHFHIPS) during post-apply bake cycles using Fourier Transform Infrared Spectroscopy (FT-IR). To avoid this problem, low volatility fluorinated inhibitors were designed and synthesized. Three fluorinated DIs, perfluorosuberic acid bis-(2,2,2,-trifluoro-1-phenyl-1-trifluoromethyl-ethyl) ester (PFSE1), perfluorosuberic acid bis-[1-(4-trifluoromethyl-phenyl)-ethyl] ester (PFSE2) and a fluorinated phenylmethanediol diester (FPMD1), largely remained in a PHFHIPS film during the post-apply bake. The dissolution behavior of the two fluorinated diesters was studied and found to slow down the dissolution rate of PHFHIPS with inhibition factors of 1.9 and 1.6, respectively. The absorbance of PHFHIPS films containing 10 wt% of the diester inhibitors is 3.6 AU/micron compared with an absorbance of 3.3 AU/micron for the polymer itself. The absorbance of 10% FPMD1 in PHFHIPS was measured as 3.5 AU/micron compared with an absorbance of 3.4 AU/micron for the polymer itself. Thus, the non-volatility and transparency of the fluorinated inhibitors at 157 nm as well as their ability to reduce the development rate of fluorinated polymers make them suitable for use in a 157 nm resist system.

  2. High power terahertz generation using 1550 nm plasmonic photomixers

    SciTech Connect

    Berry, Christopher W.; Hashemi, Mohammad R.; Jarrahi, Mona; Preu, Sascha; Lu, Hong; Gossard, Arthur C.

    2014-07-07

    We present a 1550 nm plasmonic photomixer operating under pumping duty cycles below 10%, which offers significantly higher terahertz radiation power levels compared to previously demonstrated photomixers. The record-high terahertz radiation powers are enabled by enhancing the device quantum efficiency through use of plasmonic contact electrodes, and by mitigating thermal breakdown at high optical pump power levels through use of a low duty cycle optical pump. The repetition rate of the optical pump can be specifically selected at a given pump duty cycle to control the spectral linewidth of the generated terahertz radiation. At an average optical pump power of 150 mW with a pump modulation frequency of 1 MHz and pump duty cycle of 2%, we demonstrate up to 0.8 mW radiation power at 1 THz, within each continuous wave radiation cycle.

  3. Quantitative comparison of the OCT imaging depth at 1300 nm and 1600 nm

    PubMed Central

    Kodach, V. M.; Kalkman, J.; Faber, D. J.; van Leeuwen, T. G.

    2010-01-01

    One of the present challenges in optical coherence tomography (OCT) is the visualization of deeper structural morphology in biological tissues. Owing to a reduced scattering, a larger imaging depth can be achieved by using longer wavelengths. In this work, we analyze the OCT imaging depth at wavelengths around 1300 nm and 1600 nm by comparing the scattering coefficient and OCT imaging depth for a range of Intralipid concentrations at constant water content. We observe an enhanced OCT imaging depth for 1600 nm compared to 1300 nm for Intralipid concentrations larger than 4 vol.%. For higher Intralipid concentrations, the imaging depth enhancement reaches 30%. The ratio of scattering coefficients at the two wavelengths is constant over a large range of scattering coefficients and corresponds to a scattering power of 2.8 ± 0.1. Based on our results we expect for biological tissues an increase of the OCT imaging depth at 1600 nm compared to 1300 nm for samples with high scattering power and low water content. PMID:21258456

  4. Photolysis of formic acid at 355 nm

    NASA Astrophysics Data System (ADS)

    Martinez, Denhi; Bautista, Teonanacatl; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2015-05-01

    Formic acid is well known as a food additive and recently an application on fuel cell technology has emerged. In this work we have studied the dissociative ionization process by multiphoton absorption of formic acid molecules at 355nm wavelength photons, using TOF spectrometry in reflectron mode (R-TOF). Some of the most abundant ionic fragments produced are studied at different settings of the laser harmonic generator. The dependence of the products on these conditions is reported. This work was supported by CONACYT Project 165410 and PAPIIT IN102613 and IN101215.

  5. 248nm silicon photoablation: Microstructuring basics

    NASA Astrophysics Data System (ADS)

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-01

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  6. 248nm silicon photoablation: Microstructuring basics

    SciTech Connect

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-15

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  7. 1085 nm Nd:YVO4 laser intracavity pumped at 914 nm and sum-frequency mixing to reach cyan laser at 496 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Yin, X. D.; Wang, D.; Zhang, X. H.

    2010-01-01

    We present for the first time a Nd:YVO4 laser at 1085 nm intracavity pumped at 914 nm by a Nd:YVO4 laser. We obtained intracavity powers of 57 W at 914 nm and 62 W at 1085 nm. Using type-I critical phase-matching LiB3O5 (LBO) crystal, a cyan laser at 496 nm is obtained by 914 and 1085 nm intracavity sum-frequency mixing. The maximum laser output power of 142 mW is obtained when an incident pump laser of 19.6 W is used.

  8. UV RADIATION EFFECTS ON MICROBES AND MICROBIAL PROCESSES

    EPA Science Inventory

    The ultraviolet (UV) region of solar radiation is defined as wavelengths in the range of 200 to 400 nm. In contrast to visible radiation (400 - 800 nm), which has a well-defined role as the energy source for most of the Earth's primary production, the effects of UV radiation on b...

  9. Electrically-pumped 850-nm micromirror VECSELs.

    SciTech Connect

    Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith; Keeler, Gordon Arthur; Mar, Alan

    2005-02-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

  10. Evaluation of a high exposure solar UV dosimeter for underwater use.

    PubMed

    Schouten, Peter W; Parisi, Alfio V; Turnbull, David J

    2007-01-01

    Solar ultraviolet radiation (UV) is known to have a significant effect upon the marine ecosystem. This has been documented by many previous studies using a variety of measurement methods in aquatic environments such as oceans, streams and lakes. Evidence gathered from these investigations has shown that UVB radiation (280-320 nm) can negatively affect numerous aquatic life forms, while UVA radiation (320-400 nm) can both damage and possibly even repair certain types of underwater life. Chemical dosimeters such as polysulphone have been tested to record underwater UV exposures and in turn quantify the relationship between water column depth and dissolved organic carbon levels to the distribution of biologically damaging UV underwater. However, these studies have only been able to intercept UV exposures over relatively short time intervals. This paper reports on the evaluation of a high exposure UV dosimeter for underwater use. The UV dosimeter was fabricated from poly 2,6-dimethyl-1,4-phenylene oxide (PPO) film. This paper presents the dose response, cosine response, exposure additivity and watermarking effect relating to the PPO dosimeter as measured in a controlled underwater environment and will also detail the overnight dark reaction and UVA and visible radiation response of the PPO dosimeter, which can be used for error correction to improve the reliability of the UV data measured by the PPO dosimeters. These results show that this dosimeter has the potential for long-term underwater UV exposure measurements. PMID:17645666

  11. TCSPC FLIM in the wavelength range from 800 nm to 1700 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Becker, Wolfgang; Shcheslavsky, Vladislav

    2016-03-01

    Excitation and detection in the wavelength range above 800nm is a convenient and relatively inexpensive way to increase the penetration depth in optical microscopy. Moreover, detection at long wavelength avoids the problem that tissue autofluorescence contaminates the signals from endogenous fluorescence probes. FLIM at NIR wavelength may therefore be complementary to multiphoton microscopy, especially if the lifetimes of NIR fluorophores report biological parameters of the tissue structures they are bound to. Unfortunately, neither the excitation sources nor the detectors of standard confocal and multiphoton laser scanning systems are directly suitable for excitation and detection of NIR fluorescence. Most of these problems can be solved, however, by using ps diode lasers or Ti:Sapphire lasers at their fundamental wavelength, and NIR-sensitive detectors. With NIR-sensitive PMTs the detection wavelength range can be extended up to 900 nm, with InGaAs SPAD detectors up to 1700 nm. Here, we demonstrate the use of a combination of laser scanning, multi-dimensional TCSPC, and advanced excitation sources and detectors for FLIM at up to 1700 nm. The performance was tested at tissue samples incubated with NIR dyes. The fluorescence lifetimes generally get shorter with increasing absorption and emission wavelengths of the dyes. For the cyanine dye IR1061, absorbing around 1060 nm, the lifetime was found to be as short as 70 ps. Nevertheless the fluorescence decay could still be clearly detected. Almost all dyes showed clear lifetime changes depending on the binding to different tissue constituents.

  12. Comparison of 980-nm and 1070-nm in endovenous laser treatment (EVLT)

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Tabakoglu, Ozgur; Ergenoglu, Mehmet U.; Gülsoy, Murat

    2009-07-01

    The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

  13. High power diode lasers emitting from 639 nm to 690 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

    2014-03-01

    There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

  14. Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

    NASA Astrophysics Data System (ADS)

    Fan, Shanhui; Qin, Lin; Dai, Cuixia; Zhou, Chuanqing

    2014-11-01

    We presented an improved dual channel dual focus spectral domain optical coherence tomography (SD-OCT) with two illuminations at 840 nm and 1050 nm for whole eye segment imaging and biometry in vivo. The two light beams were coupled and optically optimized to scan the anterior and posterior segment of the eye simultaneously. This configuration with dichroic mirrors integrated in the sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample signal. In addition, the full resolved complex (FRC) method was applied to double the imaging depth for the whole anterior segment imaging by eliminating the mirror image. The axial resolution for 1050 nm and 840 nm OCT was 14 μm and 8 μm in air, respectively. Finally, the system was successfully tested in imaging the unaccommodated and accommodated eyes. The preliminary results demonstrated the significant improvements comparing with our previous dual channel SD-OCT configuration in which the two probing beams had the same central wavelength of 840 nm.

  15. 308-nm excimer laser in endodontics

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  16. 1064-nm Nd:YAG laser nucleotomy

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.

    1993-07-01

    The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.

  17. Diode-pumped Nd:LuVO 4-Nd:YLiF 4 crystals blue laser at 489 nm by intracavity sum-frequency-mixing

    NASA Astrophysics Data System (ADS)

    Lü, Yan-Fei; Zhang, Xi-He; Xia, Jing; Li, Chang-Li; Zhao, Zhen-Ming; Liu, Zhi-Teng

    2010-08-01

    We present a laser architecture to obtain continuous-wave blue radiation at 489 nm. An 809 nm diode-pumped the Nd:LuVO 4 crystal emitting at 916 nm. A part of the pump power was then absorbed by the Nd:LuVO 4 crystal. The remaining was used to pump the Nd:YLiF 4 (Nd:YLF) crystal emitting at 1047 nm. Intracavity sum-frequency mixing at 916 and 1047 nm was then realized in a LiB 3O 5 (LBO) crystal to reach the blue radiation. We obtained a continuous-wave output power of 425 mW at 489 nm with a pump laser diode emitting 18.4 W at 809 nm.

  18. Diode-pumped quasi-three-level Nd:GdV O4-Nd:YAG sum-frequency laser at 464 nm

    NASA Astrophysics Data System (ADS)

    Lu, Jie

    2014-04-01

    We report a laser architecture to obtain continuous-wave (cw) blue radiation at 464 nm. A 808 nm diode pumped a Nd:GdV O4 crystal emitting at 912 nm. A part of the pump power was then absorbed by the Nd:GdV O4 crystal. The remainder was used to pump a Nd:YAG crystal emitting at 946 nm. Intracavity sum-frequency mixing at 912 and 946 nm was then realized in a LiB3O5 (LBO) crystal to produce blue radiation. We obtained a cw output power of 1.52 W at 464 nm with a pump laser diode emitting 18.4 W at 808 nm.

  19. Surface micromachined MEMS tunable VCSEL at 1550 nm with > 70 nm single mode tuning

    NASA Astrophysics Data System (ADS)

    Gierl, Christian; Gründl, Tobias; Debernardi, Pierluigi; Zogal, Karolina; Davani, Hooman A.; Grasse, Christian; Böhm, Gerhard; Meissner, Peter; Küppers, Franko; Amann, Markus-Christian

    2012-03-01

    We present surface micro-machined tunable vertical-cavity surface-emitting lasers (VCSELs) operating around 1550nm with tuning ranges up to 100nm and side mode suppression ratios beyond 40 dB. The output power reaches 3.5mW at 1555 nm. The electro-thermal and the electro-statical actuation of a micro electro-mechanical system (MEMS) movable distributed Bragg reflector (DBR) membrane increases/decreases the cavity length which shifts the resonant wavelength of the cavity to higher/lower values. The wavelength is modulated with 200 Hz/120 kHz. Both tuning mechanisms can be used simultaneously within the same device. The newly developed surface micro-machining technology uses competitive dielectric materials for the MEMS, deposited with low temperature plasma enhanced chemical vapor deposition (PECVD), which is cost effective and capable for on wafer mass production.

  20. Absorption Measurements of Periodically Poled Potassium Titanyl Phosphate (PPKTP) at 775 nm and 1550 nm

    PubMed Central

    Steinlechner, Jessica; Ast, Stefan; Krüger, Christoph; Singh, Amrit Pal; Eberle, Tobias; Händchen, Vitus; Schnabel, Roman

    2013-01-01

    The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84±40) ppm/cm and (127±24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption. PMID:23291574

  1. The Doubling of 846 nm Light to Produce 423 nm Light for use in Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Archibald, James; Birrell, Jeremey; Tang, Rebecca; Erickson, Chris; Goggins, Landon; Durfee, Dallin

    2009-10-01

    We present progress on a 423 nm fluorescence probe/cooling laser for use in our neutral calcium atom interferometer. The finished system will include an 846 nm diode laser that is coupled to a tapered amplifier. This light will be sent to a buildup cavity where we will achieve second-harmonic generation (SHG) using either a BBO non-linear crystal or a periodically-poled KTP crystal. We will discuss the theoretical considerations relating to the doubling of light in a crystal and the construction of our buildup cavity. We will also discuss its proposed application for use in atom interferometry.

  2. Measurement of 100 nm and 60 nm Particle Standards by Differential Mobility Analysis

    PubMed Central

    Mulholland, George W.; Donnelly, Michelle K.; Hagwood, Charles R.; Kukuck, Scott R.; Hackley, Vincent A.; Pui, David Y. H.

    2006-01-01

    The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.8 nm ± 1.1 nm and 60.39 nm ± 0.63 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements of aerosolized particles are made using a differential mobility analyzer (DMA) system calibrated using SRM® 1963 (100.7 nm polystyrene spheres). An electrospray aerosol generator was used for generating the 60 nm aerosol to almost eliminate the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is shown to reduce the uncertainty in the measurement of the peak particle size compared to the approach based on the peak in the concentration vs. voltage distribution. A modified aerosol/sheath inlet, recirculating sheath flow, a high ratio of sheath flow to the aerosol flow, and accurate pressure, temperature, and voltage measurements have increased the resolution and accuracy of the measurements. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.8 % of the particle size to about 1.0 %. The effect of non-volatile contaminants in the polystyrene suspensions on the peak particle size and the uncertainty in the size is determined. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the dynamic light scattering mean diameter are computed. The use of these particles for calibrating DMAs and for

  3. 11 W single gain-chip dilute nitride disk laser emitting around 1180 nm.

    PubMed

    Korpijärvi, Ville-Markus; Leinonen, Tomi; Puustinen, Janne; Härkönen, Antti; Guina, Mircea D

    2010-12-01

    We report power scaling experiments of a GaInNAs/GaAs-based semiconductor disk laser operating at ~1180 nm. Using a single gain chip cooled to mount temperature of ~10 °C we obtained 11 W of output power. For efficient thermal management we used a water-cooled microchannel mount and an intracavity diamond heat spreader. Laser performance was studied using different spot sizes of the pump beam on the gain chip and different output couplers. Intracavity frequency-doubling experiments led to generation of ~6.2 W of laser radiation at ~590 nm, a wavelength relevant for the development of sodium laser guide stars. PMID:21164909

  4. Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

    1993-01-01

    Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

  5. Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

    1988-01-01

    Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

  6. Lasing at 300 nm and below: Optical challenges and perspectives

    SciTech Connect

    Garzella, D.; Couprie, M.E. |; Billardon, M.

    1995-12-31

    The FEL experiment in the visible and near UV on the Super ACO storage ring has given, since 1989, important informations on the SRFEL dynamics and, furthermore, a very good beam stability has been achieved. In addition, the operation at 350 nm with this good stability and a long beam lifetime allowed us to perform the first user experiment in biology and to start with a campaign for using the laser as photons source for experiments in other domains, coupling FEL light and the Synchrotron Radiation. For this, FEL starts to be very competitive with respect to the other conventional laser sources, provided that it could oscillate further in the UV, say at 300 nm and below. So, the real challenge is now given by the lasing at shorter wavelengths and, for this, by the optical technology existing nowadays. Since 1992 the efforts have been concentrating to look for every kind of solution allowing us to overcome the problem of having a very low gain. From an optical point of view, in the range of wavelengths explored, there is a lack of transparents dielectric materials for substrates and coatings. Substrates are required at the same time to be relatively not absorbing (a few tens 10{sup -6}), to have a very good surface quality (RMS roughness below 10 {Angstrom}) because of scattering losses dramatically increasing in this spectral range and, due to the thermal load of the undulator emission, to have adequate thermal characteristics. In order to fulfill all these requirements, a good characterisation and modelisation of the substrates is needed, especially to correlate thermal loading and mechanical deformations from one hand, and roughness and scattering losses from the other hand. Coatings must be not absorbing too and, above all, the most amorphous as possible (this could be obtained with IBS deposition technique), in order to insure a good reproduction of the substrate roughness at the interfaces and on the top layer and an higher resistance to the XUV photons load.

  7. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  8. Infrared Radiative Properties of Food Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precisely, infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and microwaves. The infrared portion of the electromagnetic spectrum spans roughly three orders of magnitude (750 nm to 100 µm) and has been...

  9. Laser-Matter Interactions with a 527 nm Drive

    SciTech Connect

    Glenzer, S; Niemann, C; Witman, P; Wegner, P; Mason, D; Haynam, C; Parham, T; Datte, P

    2007-02-16

    The primary goal of this Exploratory Research is to develop an understanding of laser-matter interactions with 527-nm light (2{omega}) for studies of interest to numerous Laboratory programs including inertial confinement fusion (ICF), material strength, radiation transport, and hydrodynamics. In addition, during the course of this work we will develop the enabling technology and prototype instrumentation to diagnose a high fluence laser beam for energy, power, and near field intensity profile at 2{omega}. Through this Exploratory Research we have established an extensive experimental and modeling data base on laser-matter interaction with 527 nm laser light (2{omega}) in plasma conditions of interest to numerous Laboratory programs. The experiments and the laser-plasma interaction modeling using the code pF3D have shown intensity limits and laser beam conditioning requirements for future 2{omega} laser operations and target physics experiments on the National Ignition Facility (NIF). These findings have set requirements for which present radiation-hydrodynamic simulations indicate the successful generation of relevant pressure regimes in future 2{omega} experiments. To allow these experiments on the NIF, optics and optical mounts were prepared for the 18mm Second Harmonic Generation Crystal (SHG crystal) that would provide the desired high conversion efficiency from 1{omega} to 2{omega}. Supporting experimental activities on NIF included high-energy 1{omega} shots at up to 22kJ/beamline (4MJ full NIF 1{omega} equivalent energy) that demonstrated, in excess, the 1{omega} drive capability of the main laser that is required for 2{omega} operations. Also, a very extensive 3{omega} campaign was completed (see ''The National Ignition Facility Laser Performance Status'' UCRL-JRNL-226553) that demonstrated that not only doubling the laser, but also tripling the laser (a much more difficult and sensitive combination) met our model predictions over a wide range of laser

  10. Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm

    SciTech Connect

    Neumark., D.M.; Crider, P.E.; Castiglioni, L.; Kautzman, K.K.

    2009-01-21

    The photodissociation of perdeuterated propargyl (D{sub 2}CCCD) and propynyl (D{sub 3}CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 nm and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated by 248 nm or 193 nm light. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D{sub 2} loss, CD + C{sub 2}D{sub 2}, and CD{sub 3} + C{sub 2}. Obervation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D{sub 2} loss peaked at nonzero translational energy, consistent with ground state dissociation over small (< 1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.

  11. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  12. Characterization of LANDSAT Panels Using the NIST BRDF Scale from 1100 nm to 2500 nm

    NASA Technical Reports Server (NTRS)

    Markham, Brian; Tsai, Benjamin K.; Allen, David W.; Cooksey, Catherine; Yoon, Howard; Hanssen, Leonard; Zeng, Jinan; Fulton, Linda; Biggar, Stuart; Markham, Brian

    2010-01-01

    Many earth observing sensors depend on white diffuse reflectance standards to derive scales of radiance traceable to the St Despite the large number of Earth observing sensors that operate in the reflective solar region of the spectrum, there has been no direct method to provide NIST traceable BRDF measurements out to 2500 rim. Recent developments in detector technology have allowed the NIST reflectance measurement facility to expand the operating range to cover the 250 nm to 2500 nm range. The facility has been modified with and additional detector using a cooled extended range indium gallium arsenide (Extended InGaAs) detector. Measurements were made for two PTFE white diffuse reflectance standards over the 1100 nm to 2500 nm region at a 0' incident and 45' observation angle. These two panels will be used to support the OLI calibration activities. An independent means of verification was established using a NIST radiance transfer facility based on spectral irradiance, radiance standards and a diffuse reflectance plaque. An analysis on the results and associated uncertainties will be discussed.

  13. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  14. Analysis of the UV-B Regime and Potential Effects on Alfalfa

    NASA Technical Reports Server (NTRS)

    Seitz, Jeffery C.

    1998-01-01

    Life at the surface of the Earth, over the last 400 m.y., evolved under conditions of decreased short-wave radiation (i.e., ultraviolet) relative to solar output due to absorption and scattering by constituents (e.g., ozone, water vapor, aerosols) in the upper atmosphere. However, a significant amount of ultraviolet radiation in the range from 280-320 nm, known as ultraviolet-B radiation, reaches the Earth's surface and has sufficient energy to be damaging to biologic tissue. Natural fluctuations in atmospheric constituents (seasonal variation, volcanic eruptions, etc.), changes in the orbital attitude of the Earth (precession, axial tilt, orbital eccentricity), and long-term solar variability contribute to changes in the total amount of ultraviolet radiation reaching the surface of the Earth, and thus, the biosphere. More recently, the atmospheric release of commercial propellants and refrigerants, known as chlorofluorocarbons (CFCs), has contributed to a significant depletion in naturally occurring ozone in the stratosphere. Thus, decreased stratospheric ozone has resulted in an increased UV-B flux at the Earth's surface which may have profound effects on terrestrial and marine organisms. In this study, we are investigating the effects of differing solar UV-B fluxes on alfalfa (Medicago sativa L.), an important agricultural crop. A long-term goal of this research is to develop spectral signatures to detect plant response to increased UV-B radiation from remote sensor platforms.

  15. Near infrared imaging of teeth at wavelengths between 1200 and 1600 nm

    NASA Astrophysics Data System (ADS)

    Chung, Soojeong; Fried, Daniel; Staninec, Michal; Darling, Cynthia L.

    2011-03-01

    Near-IR (NIR) imaging is a new technology that is currently being investigated for the detection and assessment of dental caries without the use of ionizing radiation. Several papers have been published on the use of transillumination and reflectance NIR imaging to detect early caries in enamel. The purpose of this study was to investigate alternative near infrared wavelengths besides 1300-nm in the range from 1200- 1600-nm to determine the wavelengths that yield the highest contrast in both transmission and reflectance imaging modes. Artificial lesions were created on thirty tooth sections of varying thickness for transillumination imaging. NIR images at wavelengths from the visible to 1600-nm were also acquired for fifty-four whole teeth with occlusal lesions using a tungsten halogen lamp with several spectral filters and a Ge-enhanced CMOS image sensor. Cavity preparations were also cut into whole teeth and Z250 composite was used as a restorative material to determine the contrast between composite and enamel at NIR wavelengths. Slightly longer NIR wavelengths are likely to have better performance for the transillumination of occlusal caries lesions while 1300-nm appears best for the transillumination of proximal surfaces. Significantly higher performance was attained at wavelengths that have higher water absorption, namely 1460-nm and wavelengths greater than 1500-nm and these wavelength regions are likely to be more effective for reflectance imaging. Wavelengths with higher water absorption also provided higher contrast of composite restorations.

  16. What are the causes for the spread of GLE parameters deduced from NM data?

    NASA Astrophysics Data System (ADS)

    Bütikofer, R.; Flückiger, E.

    2015-08-01

    Investigations have shown that the analysis results of ground level enhancements (GLEs) based on neutron monitor (NM) data for a selected event can differ considerably depending the procedure used. This may have significant consequences e.g. for the assessment of radiation doses at flight altitudes. The reasons for the spread of the GLE parameters deduced from NM data can be manifold and are at present unclear. They include differences in specific properties of the various analysis procedures (e.g. NM response functions, different ways in taking into account the dynamics of the Earth's magnetospheric field), different characterisations of the solar particle flux near Earth as well as the specific selection of NM stations used for the analysis. In the present paper we quantitatively investigate this problem for a time interval during the maximum phase of the GLE on 13 December 2006. We present and discuss the changes in the resulting GLE parameters when using different NM response functions, different model representations of the Earth's magnetospheric field as well as different assumptions for the solar particle spectrum and pitch angle distribution near Earth. The results of the study are expected to yield a basis for the reduction in the spread of the GLE parameters deduced from NM data.

  17. Faster qualification of 193-nm resists for 100-nm development using photo cell monitoring

    NASA Astrophysics Data System (ADS)

    Jones, Chris M.; Kallingal, Chidam; Zawadzki, Mary T.; Jeewakhan, Nazneen N.; Kaviani, Nazila N.; Krishnan, Prakash; Klaum, Arthur D.; Van Ess, Joel

    2003-05-01

    The development of 100-nm design rule technologies is currently taking place in many R&D facilities across the world. For some critical alyers, the transition to 193-nm resist technology has been required to meet this leading edge design rule. As with previous technology node transitions, the materials and processes available are undergoing changes and improvements as vendors encounter and solve problems. The initial implementation of the 193-nm resits process did not meet the photolithography requirements of some IC manufacturers due to very high Post Exposure Bake temperature sensitivity and consequently high wafer to wafer CD variation. The photoresist vendors have been working to improve the performance of the 193-nm resists to meet their customer's requirements. Characterization of these new resists needs to be carried out prior to implementation in the R&D line. Initial results on the second-generation resists evaluated at Cypress Semicondcutor showed better CD control compared to the aelrier resist with comparable Depth of Focus (DOF), Exposure Latitute, Etch Resistance, etc. In addition to the standard lithography parameters, resist characterization needs to include defect density studies. It was found that the new resists process with the best CD control, resulted in the introduction of orders of magnitude higher yield limiting defects at Gate, Contact adn Local Interconnect. The defect data were shared with the resists vendor and within days of the discovery the resist vendor was able to pinpoint the source of the problem. The fix was confirmed and the new resists were successfully released to production. By including defect monitoring into the resist qualification process, Cypress Semiconductor was able to 1) drive correction actions earlier resulting in faster ramp and 2) eliminate potential yield loss. We will discuss in this paper how to apply the Micro Photo Cell Monitoring methodology for defect monitoring in the photolithogprhay module and the

  18. 65nm RadSafe™ Technology for RC64 and Advanced SOCs

    NASA Astrophysics Data System (ADS)

    Liran, Tuvia; Ginosar, Ran; Lange, Fredy; Mandler, Alberto; Aviely, Peleg; Meirov, Henri; Goldberg, Michael; Meister, Zeev; Oliel, Mickey

    2015-09-01

    The trend of scaling of microelectronic provides certain advantages for space components, as well as some challenges. It enables implementing highly integrated and high performance ASICs, reducing power, area and weight. Scaling also improves the immunity to TID and SEL in most cases, but increases soft error rate significantly. Ramon Chips adopted the 65nm technology for implementing RC64 [1,2], a 64 core DSP for space applications, and for making other future products. The 65nm process node is widely used, very mature, and supported by wide range of IP providers. Thus the need for full custom design of cores and IPs is minimized, and radiation hardening is achievable by mitigating the radiation effects on the available IPs, and developing proprietary IPs only for complementing the available IPs. The RadSafe_65TM technology includes hardened standard cells and I/O libraries, methods for mitigation of radiation effects in COTS IP cores (SRAM, PLL, SERDES, DDR2/3 interface) and adding unique cores for monitoring radiation effects and junction temperature. We had developed RADIC6, a technology development vehicle, for verification of all hard cores and verification of the methodologies and design flow required for RC64. RADIC6 includes the test structures for characterizing the IP cores for immunity to all radiation effects. This paper describes the main elements and IP cores of RadSafe_65TM, as well as the contents of RADIC6 test chip.

  19. Emission in argon and krypton at 147 nm excited by runaway-electron-induced diffusion discharge

    SciTech Connect

    Gerasimov, Gennadii N; Krylov, B E; Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F

    2010-05-26

    Plasma emission of a pulsed diffuse discharge produced at increased pressures due to the preionisation of the gap by runaway electrons is studied in argon, krypton, and xenon. Nanosecond voltage pulses with the amplitude {approx}220 kV were applied to the discharge gap. It is shown that the presence of xenon ({approx}0.01%) in argon and krypton leads to the emergence of high-power narrowband radiation at awavelength of 147 nm. It is assumed that this radiation belongs to the bands of heteronuclear molecules Xe*Ar and Xe*Kr.

  20. Collateral damage-free debridement using 193nm ArF laser

    NASA Astrophysics Data System (ADS)

    Wynne, James J.; Felsenstein, Jerome M.; Trzcinski, Robert; Zupanski-Nielsen, Donna; Connors, Daniel P.

    2011-03-01

    Burn eschar and other necrotic areas of the skin and soft tissue are anhydrous compared to the underlying viable tissue. A 193 nm ArF excimer laser, emitting electromagnetic radiation at 6.4 eV at fluence exceeding the ablation threshold, will debride such necrotic areas. Because such radiation is strongly absorbed by aqueous chloride ions through the nonthermal process of electron photodetachment, debridement will cease when hydrated (with chloride ions) viable tissue is exposed, avoiding collateral damage to this tissue. Such tissue will be sterile and ready for further treatment, such as a wound dressing and/or a skin graft.

  1. Low-cost, broadly tunable (375-433 nm & 746-887 nm) Cr:LiCAF laser pumped by one single-spatial-mode diode.

    PubMed

    Demirbas, Umit; Uecker, Reinhard; Klimm, Detlef; Wang, Jing

    2012-12-10

    We describe a low-cost, compact, and efficient Cr(3+):LiCaAlF(6) (Cr:LiCAF) laser that is broadly tunable in the near infrared (746-887 nm) and blue/ultraviolet (375-433 nm) regions of the optical spectrum. The pump source is a 660 nm single-mode-diode with 145 mW of output power. A melt-grown Cr:LiCAF crystal with an extremely high figure of merit above 2000 was used as the gain medium. This enabled the construction of a high-Q-cavity with continuous wave (cw) lasing thresholds as low as 3 mW, slope efficiencies as high as 54%, and output powers up to 63 mW. The stored intracavity power levels were above 30 W. By placing a beta-barium-borate crystal at a second intracavity focus, we could obtain tunable cw blue/ultraviolet radiation with output powers up to 3.5 mW around 400 nm. When mode-locked using a saturable Bragg reflector around 800 nm, the Cr:LiCAF laser produced 95 fs pulses with average powers of 33 mW and peak powers of 3.58 kW at a repetition rate of 85.5 MHz. Extracavity second harmonic generation enables generation of femtosecond pulses around 400 nm. These results demonstrate the possibility to grow Cr:LiCAF crystals with passive losses below 0.15% per cm, which enables construction of low-cost and complexity systems that are pumped only with one low-power single-mode-diode. PMID:23262540

  2. Radiation sickness

    MedlinePlus

    ... to determine the amount of radiation exposure from nuclear accidents, the best signs of the severity of the ... doses of radiation, such as radiation from a nuclear power plant accident Exposure to excessive radiation for medical treatments

  3. Thin film type 248-nm bottom antireflective coatings

    NASA Astrophysics Data System (ADS)

    Enomoto, Tomoyuki; Nakayama, Keisuke; Mizusawa, Kenichi; Nakajima, Yasuyuki; Yoon, Sangwoong; Kim, Yong-Hoon; Kim, Young-Ho; Chung, Hoesik; Chon, Sang Mun

    2003-06-01

    A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13-micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity towards resist. SAMSUNG Electronics has developed the advanced Organic BARC with Nissan Chemical Industries, Ltd. and Brewer Science, Inc. for achieving the above purpose. As a result, the suitable high performance SNAC2002 series KrF Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of SNAC2002 series is about 1.4 times higher than that of conventional KrF resists and 1.25 times higher than the existing product. The SNAC2002 series can minimize the substrate reflectivity at below 40nm BARC thickness, shows excellent litho performance and coating properties.

  4. 10{times} reduction imaging at 13.4nm

    SciTech Connect

    Tichenor, D.A.; Kubiak, G.D.; Malinowski, M.E.

    1994-08-01

    A Schwarzschild imaging system has been designed to achieve 0.1 {mu}m resolution in a 0.4 mm diameter field of view when operated at a center wavelength of 13.4 nm. A decentered aperture is located on the convex primary resulting in an unobstructed numerical aperture of 0.08 and a corresponding depth of field of {plus_minus} 1 {mu}m. The Schwarzschild imaging objective is part of a five-reflection system containing the laser plasma source (LPS), condensing optics, turning mirror and reflection mask as shown in Figure 1. Extreme ultraviolet (EUV) radiation is generated by impinging a laser beam onto a copper target. The plasma source is driven by a Lambda Physik PLX 250 KrF excimer laser emitting 0.6 Joule, 20 ns pulses at a 200 Hz maximum repetition rate. Measurements of the source indicate that the full-width-half-maximum diameter is less than 100 {mu}m.

  5. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  6. Injection locking of a diode-pumped Nd:YAG laser at 946 nm

    SciTech Connect

    Hollemann, G.; Peik, E.; Rusch, A.; Walther, H.

    1995-09-15

    Injection locking in the quasi-three-level laser system Nd:YAG {sup 4}{ital F}{sub 3/2}--{sup 4}{ital I}{sub 9/2} at 946 nm is reported. The master and slave oscillators are pumped by laser diodes. The master oscillator is frequency stabilized to a high-finesse cavity, resulting in a laser linewidth of less than 10 Hz. Using intracavity frequency doubling of the slave oscillator, we achieve a single-mode output power of 60 mW at 473 nm. The laser radiation was frequency quadrupled, resulting in an UV power of 0.55 mW at 236.5 nm. The laser system was used to excite a strongly forbidden In{sup +} transition, proposed as a new optical frequency standard. {copyright} 1995 Optical Society of America

  7. Gd plasma source modeling at 6.7 nm for future lithography

    SciTech Connect

    Li Bowen; Dunne, Padraig; O'Sullivan, Gerry; Higashiguchi, Takeshi; Yugami, Noboru; Otsuka, Takamitsu; Jiang, Weihua; Endo, Akira

    2011-12-05

    Plasmas containing gadolinium have been proposed as sources for next generation lithography at 6.x nm. To determine the optimum plasma conditions, atomic structure calculations have been performed for Gd{sup 11+} to Gd{sup 27+} ions which showed that n = 4 - n = 4 resonance transitions overlap in the 6.5-7.0 nm region. Plasma modeling calculations, assuming collisional-radiative equilibrium, predict that the optimum temperature for an optically thin plasma is close to 110 eV and that maximum intensity occurs at 6.76 nm under these conditions. The close agreement between simulated and experimental spectra from laser and discharge produced plasmas indicates the validity of our approach.

  8. 2.14 mW deep-ultraviolet laser at 165 nm by eighth-harmonic generation of a 1319 nm Nd:YAG laser in KBBF

    NASA Astrophysics Data System (ADS)

    Dai, Shi-Bo; Chen, Ming; Zhang, Shen-Jin; Wang, Zhi-Min; Zhang, Feng-Feng; Yang, Feng; Wang, Zhi-Chao; Zong, Nan; Liu, Li-Juan; Wang, Xiao-Yang; Zhang, Jing-Yuan; Bo, Yong; Cui, Da-Fu; Peng, Qin-Jun; Li, Ru-Kang; Chen, Chuang-Tian; Xu, Zu-Yan

    2016-03-01

    We report a nanosecond (ns) 165 nm deep-ultraviolet (DUV) laser with a maximum average power of 2.14 mW by eighth-harmonic generation (EHG) of a homemade ns 1319 nm Nd:YAG laser. The EHG was performed by cascaded second-harmonic generation (SHG) through successive stages of two LiB3O5 crystals and one KBe2BO3F2 crystal. The generated radiation at 165 nm is the shortest DUV wavelength ever generated through SHG method and the highest average power of all solid state lasers below 170 nm to our knowledge. Such a ns DUV laser at 165 nm is of great interest for photoemission spectroscopy and Raman spectroscopy.

  9. Radiation dosimetry.

    PubMed Central

    Cameron, J

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists. PMID:2040250

  10. Imaging at high spatial resolution: Soft x-ray microscopy to 15nm

    SciTech Connect

    Attwood, D.; Chao, W.; Anderson, E.; Liddle, J.A.; Harteneck, B.; Fischer, P.; Schneider, G.; Le Gros, M.; Larabell, C.

    2006-04-05

    Soft x-ray microscopy has now achieved 15 nm spatial resolution with new zone plates and bending magnet radiation. Combined with elemental sensitivity and flexible sample environment (applied magnetic or electric fields, wet samples, windows, overcoatings) this emerges as a valuable tool for nanoscience and nanotechnology, complimenting common electron and scanning tip microscopies. In this presentation we describe recent advances in spatial resolution, expectations for the near future, and applications to magnetic materials, bio-tomography, etc.

  11. Sub-500  nm hard x ray focusing by compound long kinoform lenses.

    PubMed

    Liao, Keliang; Liu, Jing; Liang, Hao; Wu, Xuehui; Zhang, Kai; Yuan, Qingxi; Yi, Futing; Sheng, Weifan

    2016-01-01

    The focusing performance of polymethyl methacrylate compound long kinoform lenses with 70 μm aperture and 19.5 mm focal length was characterized with 8 keV x rays using the knife-edge scan method at the 4W1A transmission x-ray microscope beamline of Beijing Synchrotron Radiation Facility. The experiment result shows a best FWHM focus size of 440 nm with 31% diffraction efficiency. PMID:26835618

  12. Fast dispersion encoded full range OCT for retinal imaging at 800 nm and 1060 nm

    NASA Astrophysics Data System (ADS)

    Hofer, Bernd; Považay, Boris; Unterhuber, Angelika; Wang, Ling; Hermann, Boris; Rey, Sara; Matz, Gerald; Drexler, Wolfgang

    2011-03-01

    The dispersion mismatch between sample and reference arm in frequency-domain OCT can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. We propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed for in vivo retinal tomograms at 800 nm. Best results have been achieved with about 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves an average suppression ratio of 55 dB and converges within 5 to 10 iterations. The processing time on non-dedicated hardware was 5 to 10 seconds for tomograms with 512 depth scans and 4096 sampling points per depth scan. Application of DEFR to the more challenging 1060 nm wavelength region is demonstrated by introducing an additional optical fibre in the sample arm.

  13. Polarization properties of lidar scattering from clouds at 347 nm and 694 nm.

    PubMed

    Pal, S R; Carswell, A I

    1978-08-01

    The polarization characteristics of lidar scattering from cumulus and low-lying shower clouds have been measured with a system operating at 694 nm (red) and 347 nm (blue). The backscatter profiles of the polarization components as well as of the total intensity of the return are presented and discussed for the two wavelengths. The linear depolarization ratio delta, which can be used as a measure of the unpolarized multiple scattering, has been obtained at both wavelengths. This quantity has a very low value at cloud base for both wavelengths and increases with pulse penetration. The blue registers generally higher values of a within the cloud. The measured total intensity backscatter functions for both wavelengths are presented and discussed in relation to theoretical calculations of cloud models. PMID:20203781

  14. TUNABLE DIODE LASER MEASUREMENTS OF NO2 NEAR 670 NM AND 395 NM. (R823933)

    EPA Science Inventory

    Two single-mode diode lasers were used to record high-resolution absorption spectra of NO2 (dilute in Ar) near 670.2 and 394.5 nm over a range of temperatures (296 to 774 K) and total pressures (2.4 x 10(-2) to 1 atm). A commercial InGaAsP laser was tuned 1.3 cm(-1) at a repetiti...

  15. Analysis of multi-mode to single-mode conversion at 635 nm and 1550 nm

    NASA Astrophysics Data System (ADS)

    Zamora, Vanessa; Bogatzki, Angelina; Arndt-Staufenbiel, Norbert; Hofmann, Jens; Schröder, Henning

    2016-03-01

    We propose two low-cost and robust optical fiber systems based on the photonic lantern (PL) technology for operating at 635 nm and 1550 nm. The PL is an emerging technology that couples light from a multi-mode (MM) fiber to several single-mode (SM) fibers via a low-loss adiabatic transition. This bundle of SM fibers is observed as a MM fiber system whose spatial modes are the degenerate supermodes of the bundle. The adiabatic transition allows that those supermodes evolve into the modes of the MM fiber. Simulations of the MM fiber end structure and its taper transition have been performed via functional mode solver tools in order to understand the modal evolution in PLs. The modelled design consists of 7 SM fibers inserted into a low-index capillary. The material and geometry of the PLs are chosen such that the supermodes match to the spatial modes of the desired step-index MM fiber in a moderate loss transmission. The dispersion of materials is also considered. These parameters are studied in two PL systems in order to reach a spectral transmission from 450 nm to 1600 nm. Additionally, an analysis of the geometry and losses due to the mismatching of modes is presented. PLs are typically used in the fields of astrophotonics and space photonics. Recently, they are demonstrated as mode converters in telecommunications, especially focusing on spatial division multiplexing. In this study, we show the use of PLs as a promising interconnecting tool for the development of miniaturized spectrometers operating in a broad wavelength range.

  16. Active radiation hardening technology for fiber-optic source

    NASA Astrophysics Data System (ADS)

    Yang, Yuanhong; Suo, Xinxin; Yang, Mingwei

    2013-09-01

    We demonstrated an active radiation hardening technology for fiber optic source developed for high performance fiber optic gyroscope. The radiation characteristic of erbium-doped fiber was studied experimentally. The radiation induced attenuation (RIA) at 980nm pump light was identified to be the main reason for the degradation and there was photo-bleaching effect in EDF too. A variable parameters control technology was proposed and taken to keep the 980nm and 1550nm light energy stable and high stability and radiation-resistance fiber source with gauss profile spectrum was realized .The source can stand against more than 50 krad (Si) total radiation dose.

  17. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    DOE PAGESBeta

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; et al

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environmentsmore » for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.« less

  18. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    SciTech Connect

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; Schrimpf, R. D.; Labello, R.; Nichols, J.; Weeden-Wright, S. L.

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environments for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.

  19. Demonstration of a high output power 1533nm optical parametric oscillator pumped at 1064nm

    NASA Astrophysics Data System (ADS)

    Foltynowicz, Robert J.; Wojcik, Michael D.

    2010-10-01

    A high output power, eye-safe, LIDAR transmitter based on a KTA optical parametric oscillator (OPO) was demonstrated. The OPO was based on a two crystal, NCPM, KTA ring cavity which was doubly resonant. A 7ns, 30Hz, flashlamp-pumped, Q-switched Nd:YAG laser was injection seeded and used to pump the OPO. The OPO converted the 1064 nm pump beam into a 1533 nm signal wave and 3475 nm idler wave. In addition to demonstrating a high power OPO system, we investigated the effects of seeding the pump laser on the OPO's conversion efficiency, oscillation threshold, maximum signal power, and beam quality. The power conversion efficiency between the signal and the injection seeded pump was 22% with an oscillation threshold of 104 MW/cm2 (500 mJ) and a maximum signal power of 6.44 W (215 mJ). The power conversion efficiency between the signal and the unseeded pump was 24% with an oscillation threshold of 77 MW/cm2 (367mJ) and a maximum signal power of 7 W (233 mJ). The beam quality of the signal beam was produced an M2 =15. When the pump laser was seeded, the full angle divergence improved by nearly a factor of five.

  20. Tunable UV generation at 286 nm by frequency tripling of a high-power mode-locked semiconductor laser

    SciTech Connect

    Goldberg, L.; Kliner, D.A.V.

    1995-08-01

    We produced ultraviolet radiation by frequency tripling the mode-locked emission of an external cavity laser containing a tapered GaAlAs amplifier gain element. The 429-nm second harmonic produced by a KNbO{sub 3} crystal was sum-frequency mixed with the 858-nm fundamental in a Li{sub 3}BO{sub 5} crystal, generating as much as 50{mu}W of power at 286 nm. {copyright} {ital 1995} {ital Optical} {ital Society} {ital of} {ital America}.

  1. 504 nm blue-green laser based on sum-frequency mixing of diode pumped Nd3+ lasers

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Jin, G. Y.; Dong, Y.

    2011-08-01

    We report for the first time a continuous-wave (CW) blue-green radiation at 504 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1080 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 504 nm blue-green laser was obtained by 946 and 1080 nm intra-cavity sum-frequency mixing, and output power of 215 mW was demonstrated. At the output power level of 215 mW, the output power stability is better than 4.7% and laser beam quality M2 factor is 1.21.

  2. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    SciTech Connect

    Thiyagarajan, Magesh; Thompson, Shane

    2012-04-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then

  3. Designing dual-trench alternating phase-shift masks for 140-nm and smaller features using 248-nm KrF and 193-nm ArF lithography

    NASA Astrophysics Data System (ADS)

    Petersen, John S.; Socha, Robert J.; Naderi, Alex R.; Baker, Catherine A.; Rizvi, Syed A.; Van Den Broeke, Douglas J.; Kachwala, Nishrin; Chen, J. Fung; Laidig, Thomas L.; Wampler, Kurt E.; Caldwell, Roger F.; Takeuchi, Susumu; Yamada, Yoshiro; Senoh, Takashi; McCallum, Martin

    1998-09-01

    One method for making the alternating phase-shift mask involves cutting a trench into the quartz of the mask using an anisotropic dry etch, followed by an isotropic etch to move the corners of the trench underneath the chrome to minimize problems caused by diffraction at the bottom corners of the phase-trench. This manufacturing method makes the addition of subresolution scattering bars and serifs problematic, because the amount of the undercut causes chrome lifting of these small features. Adding an additional anisotropically etched trench to both cut and uncut regions is helpful, but the etch does not move the trench corners under the chrome and result in a loss to intensity and image contrast. At 248 nm illumination and 4X magnification, our work shows that a combination of 240 nm dual-trench and 5 nm to 10 nm undercut produces images with equal intensity between shifted and unshifted regions without loss of image contrasts. This paper demonstrates optical proximity correction for doing 100 nm, 120 nm, 140 nm and 180 nm lines of varying pitch for a simple alternating phase-shift mask, with no dual-trench or undercut. Then the electromagnetic field simulator, TEMPEST, is used to find the best combination of dual-trench depth and amount of undercut for an alternating phase-shift mask. Phase measurement using 248 nm light and depth measurement of thirty-six unique combinations of dual-trench and phase-shift trench are shown. Based on modeling and experimental results, recommendations for making a fine tuned dual-trench 248 nm mask, as well as an extension of the dual-trench alternating phase-shift technique to 193 nm lithography, are made.

  4. High performance spectrograph for solar UV 250-400 band

    NASA Astrophysics Data System (ADS)

    Di Menno, I.; Rafanelli, C.; De Simone, S.; Di Menno, M.

    2007-09-01

    The solar electromagnetic radiation flux is one of the important factors to evaluate the energy balance of the planet. It is important in the studies on the properties of the atmosphere and its components as AOD, on the energy requirements for anthropogenic activities as agriculture, industry and so on. The ever-increasing interest about the effects on the biosphere as consequence of anthropogenic activities has contributed to develop further studies about the solar radiation and in particular the UV band, 280-320 nm. The consequence has been a growing of instrumental site and radiometric networks. Many decisions affecting on civil society are taken using the data of these nets and consequently it is very important to study the effect of the environmental factors on the instrument output. The classical electromechanical equipments have good sensibility and resolution but their handicap is the time of the measure, generally some minutes. In this time, the sun is moved and the clouds in the sky too. The new generation of spectrometer based on solid state technology avoid the long time measurements. The paper show a new radiograph (fast spectroradiometer) for solar UV band 250-400 nm. It is based on CCD array and optical fiber. The performance are compared with a Brewer spectrophotometer during a comparison campaign close to Rome, Italy.

  5. Ultralow-threshold electrically injected AlGaN nanowire ultraviolet lasers on Si operating at low temperature.

    PubMed

    Li, K H; Liu, X; Wang, Q; Zhao, S; Mi, Z

    2015-02-01

    Ultraviolet laser radiation has been adopted in a wide range of applications as diverse as water purification, flexible displays, data storage, sterilization, diagnosis and bioagent detection. Success in developing semiconductor-based, compact ultraviolet laser sources, however, has been extremely limited. Here, we report that defect-free disordered AlGaN core-shell nanowire arrays, formed directly on a Si substrate, can be used to achieve highly stable, electrically pumped lasers across the entire ultraviolet AII (UV-AII) band (∼320-340 nm) at low temperatures. The laser threshold is in the range of tens of amps per centimetre squared, which is nearly three orders of magnitude lower than those of previously reported quantum-well lasers. This work also reports the first demonstration of electrically injected AlGaN-based ultraviolet lasers monolithically grown on a Si substrate, and offers a new avenue for achieving semiconductor lasers in the ultraviolet B (UV-B) (280-320nm) and ultraviolet C (UV-C) (<280 nm) bands. PMID:25599190

  6. Ultralow-threshold electrically injected AlGaN nanowire ultraviolet lasers on Si operating at low temperature

    NASA Astrophysics Data System (ADS)

    Li, K. H.; Liu, X.; Wang, Q.; Zhao, S.; Mi, Z.

    2015-02-01

    Ultraviolet laser radiation has been adopted in a wide range of applications as diverse as water purification, flexible displays, data storage, sterilization, diagnosis and bioagent detection. Success in developing semiconductor-based, compact ultraviolet laser sources, however, has been extremely limited. Here, we report that defect-free disordered AlGaN core-shell nanowire arrays, formed directly on a Si substrate, can be used to achieve highly stable, electrically pumped lasers across the entire ultraviolet AII (UV-AII) band (˜320-340 nm) at low temperatures. The laser threshold is in the range of tens of amps per centimetre squared, which is nearly three orders of magnitude lower than those of previously reported quantum-well lasers. This work also reports the first demonstration of electrically injected AlGaN-based ultraviolet lasers monolithically grown on a Si substrate, and offers a new avenue for achieving semiconductor lasers in the ultraviolet B (UV-B) (280-320nm) and ultraviolet C (UV-C) (<280 nm) bands.

  7. Prophylaxis and treatment of acute radiation ulcers in rats with low-power infrared laser radiation

    NASA Astrophysics Data System (ADS)

    Kursova, Larisa V.; Kaplan, Michael A.; Nikitina, Rosa G.; Maligina, Antonina I.

    1999-12-01

    Exposure of radiation ulcers in rats to low-power infrared laser radiation (LPLR) (wavelength--890 nm, pulse power--6 W, frequency--150 and 300 Hz, irradiation time--10 min) noticeably accelerates their healing, reduces exudative processes, increases number of specialized cells in wound. Application of LPLR prior to radiation damage decreases ulcer dimensions.

  8. Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy

    NASA Astrophysics Data System (ADS)

    Grifoni, D.; Carreras, G.; Zipoli, G.; Sabatini, F.; Dalla Marta, A.; Orlandini, S.

    2008-11-01

    Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines ( Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade.

  9. First principles study on the interfacial properties of NM/graphdiyne (NM = Pd, Pt, Rh and Ir): The implications for NM growing

    NASA Astrophysics Data System (ADS)

    Lu, Zhansheng; Li, Shuo; Lv, Peng; He, Chaozheng; Ma, Dongwei; Yang, Zongxian

    2016-01-01

    Based on the dispersion-corrected density functional calculations (DFT-D), we systematically studied the adsorption of noble metals (NM), Pd, Pt, Rh and Ir, on graphdiyne (GDY). We present a systematic study on the geometry, embedded adsorption energy and electronic structure of four different adatoms adsorbed on the GDY. The strong interaction between the NM adatoms and the GDY substrate is found with the NM embedded in the 18C-hexagon of the GDY. We investigated the mobility of the NM adatoms on the GDY, and found that the mobility barrier energy increases along with the increasing of the embedded adsorption energy. We present the NM adatoms growth of high concentrations on the GDY. Upon the analysis of the electronic structure and the frontier molecular orbitals, Rh and Ir adatoms of low concentrations (about 1.37 at%) on the GDY have the potential to be applied as single metal catalysts or gas molecule sensors.

  10. UV 380 nm Reflectivity of the Earth's Surface

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Celarier, E.; Larko, D.

    2000-01-01

    The 380 nm radiance measurements of TOMS (Total Ozone Mapping Spectrometer) have been converted into a global data set of daily (1979 to 1992) Lambert equivalent reflectivities R of the Earth's surface and boundary layer (clouds, aerosols, surface haze, and snow/ice). Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicates the presence of clouds, haze, or aerosols in the satellite field of view. Statistical analysis of 14 years of daily data show that most snow/ice-free regions of the Earth have their largest fraction of days each year when the reflectivity is low (R less than 10%). The 380 nm reflectivity data shows that the true surface reflectivity is 2 to 3% lower than the most frequently occurring reflectivity value for each TOMS scene. The most likely cause of this could be a combination of frequently occurring boundary-layer water or aerosol haze. For most regions, the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are cloud-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain-forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant cloud cover (R greater than 15%) more than half of each year. In the low to middle latitudes, the areas with the heaviest cloud cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show the presence of large nearly clear ocean areas and the effects

  11. Cycloolefin/cyanoacrylate (COCA) copolymers for 193-nm and 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Dammel, Ralph R.; Sakamuri, Raj; Lee, Sang-Ho; Rahman, Dalil; Kudo, Takanori; Romano, Andrew R.; Rhodes, Larry F.; Lipian, John-Henry; Hacker, Cheryl; Barnes, Dennis A.

    2002-07-01

    The copolymerization reaction between methyl cyanoacrylate (MCA) and a variety of cycloolefins (CO) was investigated. Cycololefin/cyanoacrylate (COCA) copolymers were obtained in good yields and with lithographically interesting molecular weights for all cycoolefins studied. Anionic MCA homopolymerization could be largely suppressed using acetic acid. Based on NMR data, the copolymerization may tend to a 1:1 CO:MCA incorporation ratio but further work with better suppression of the anionic component is needed to confirm this. Lithographic tests on copolymers of appropriately substituted norbornenes and MCA showed semi-dense and isolated line performance down to 90 nm.

  12. The Mg 280-nm doublet as a monitor of changes in solar ultraviolet irradiance

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Schlesinger, B. M.

    1986-01-01

    Solar irradiance data gathered with the Nimbus 7 spacecraft from 1978-1985 are compared with atmospheric MG 289-nm doublet emission line data to evaluate the possibility of using the rotational line data to calculate the total solar UV input. The satellite instrumentation is described, including the calibration equipment and procedures. The spacecraft records solar irradiance once per day and the remainder of the time records irradiance scattered by the atmosphere. The measured irradiances are converted to equivalent brightness temperatures, which can be interpolated for specific layers of the atmosphere. Sample daily data are provided to illustrate the correlation between variations in the Mg-II core radiation and the soalr UV irradiance. Techniques are defined for correcting for periodic variations in instrument performance to quantify long-term solar UV radiance variations. Using the atmospheric Mg-II doublet radiation for measuring soalr UV irradiance is concluded of value for characterizing the effects of solar radiation on the atmosphere.

  13. EUV light source with high brightness at 13.5 nm

    SciTech Connect

    Borisov, V M; Prokof'ev, A V; Khristoforov, O B; Koshelev, K N; Khadzhiyskiy, F Yu

    2014-11-30

    The results of the studies on the development of a highbrightness radiation source in the extreme ultraviolet (EUV) range are presented. The source is intended for using in projection EUV lithography, EUV mask inspection, for the EUV metrology, etc. Novel approaches to creating a light source on the basis of Z-pinch in xenon allowed the maximal brightness [130 W(mm{sup 2} sr){sup -1}] to be achieved in the vicinity of plasma for this type of radiation sources within the 2% spectral band centred at the wavelength of 13.5 nm that corresponds to the maximal reflection of multilayer Mo/Si mirrors. In this spectral band the radiation power achieves 190 W in the solid angle of 2π at a pulse repetition rate of 1.9 kHz and an electric power of 20 kW, injected into the discharge. (laser applications and other topics in quantum electronics)

  14. Suppression of high-order-harmonic intensities observed in aligned CO2 molecules with 1300-nm and 800-nm pulses

    NASA Astrophysics Data System (ADS)

    Kato, Kosaku; Minemoto, Shinichirou; Sakai, Hirofumi

    2011-08-01

    High-order-harmonic generation from aligned N2, O2, and CO2 molecules is investigated by 1300-nm and 800-nm pulses. The harmonic intensities of 1300-nm pulses from aligned molecules show harmonic photon energy dependence similar to those of 800-nm pulses. Suppression of harmonic intensity from aligned CO2 molecules is observed for both 1300- and 800-nm pulses over the same harmonic photon energy range. As the dominant mechanism for the harmonic intensity suppression from aligned CO2 molecules, the present results support the two-center interference picture rather than the dynamical interference picture.

  15. Flux-calibration of medium-resolution spectra from 300 nm to 2500 nm

    NASA Astrophysics Data System (ADS)

    Moehler, Sabine; Modigliani, Andrea; Freudling, Wolfram; Giammichele, Noemi; Gianninas, Alexandros; Gonneau, Anais; Kausch, Wolfgang; Lançon, Ariane; Noll, Stefan; Rauch, Thomas; Vinther, Jakob

    2014-08-01

    While the near-infrared wavelength regime is becoming more and more important for astrophysics there are few spectrophotometric standard star data available to flux calibrate such data. On the other hand flux calibrating high-resolution spectra is a challenge even in the optical wavelength range, because the available flux standard data are often too coarsely sampled. We describe a method to obtain reference spectra derived from stellar model atmospheres, which allow users to derive response curves from 300 nm to 2500 nm also for high-resolution spectra. We verified that they provide an appropriate description of the observed standard star spectra by checking for residuals in line cores and line overlap regions in the ratios of observed spectra to model spectra. The finally selected model spectra are then empirically corrected for remaining mismatches and photometrically calibrated using independent observations. In addition we have defined an automatic method to correct for moderate telluric absorption using telluric model spectra with very high spectral resolution, that can easily be adapted to the observed data. This procedure eliminates the need to observe telluric standard stars, as long as some knowledge on the target spectrum exists.

  16. On Helium 1083 nm Line Polarization during the Impulsive Phase of an X1 Flare

    NASA Astrophysics Data System (ADS)

    Judge, Philip G.; Kleint, Lucia; Sainz Dalda, Alberto

    2015-12-01

    We analyze spectropolarimetric data of the He i 1083 nm multiplet (1s2s{}3{S}1-1s2p{}3{P}2,1,0o) during the X1 flare SOL2014-03-29T17:48, obtained with the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope. While scanning active region NOAA 12017, the FIRS slit crossed a flare ribbon during the impulsive phase, when the helium line intensities turned into emission at ≲twice the continuum intensity. Their linear polarization profiles are of the same sign across the multiplet including 1082.9 nm, intensity-like, at ≲5% of the continuum intensity. Weaker Zeeman-induced linear polarization is also observed. Only the strongest linear polarization coincides with hard X-ray (HXR) emission at 30-70 keV observed by RHESSI. The polarization is generally more extended and lasts longer than the HXR emission. The upper J = 0 level of the 1082.9 nm component is unpolarizable thus, lower-level polarization is the culprit. We make non-LTE radiative transfer calculations in thermal slabs optimized to fit only intensities. The linear polarizations are naturally reproduced, through a systematic change of sign with wavelength of the radiation anisotropy when slab optical depths of the 1082.9 component are ≲1. Neither are collisions with beams of particles needed, nor can they produce the same sign of polarization of the 1082.9 and 1083.0 nm components. The He i line polarization merely requires heating sufficient to produce slabs of the required thickness. Widely different polarizations of Hα, reported previously, are explained by different radiative anisotropies arising from slabs of different optical depths.

  17. Photoconductive response of type IIa diamond in the 222-353-nm range

    NASA Astrophysics Data System (ADS)

    Krishnan, Mahadevan; Lipatov, Evgenii E. I.; Parks, D.; Panchenko, Alexei N.; Schein, Jochen; Tarasenko, Victor F.; Thompson, J.

    2004-05-01

    Diamond radiation detectors (DRDs) operate on the principle of photoconductive response of the normally insulating, Type IIa diamond when dosed by electromagnetic radiation or high energy particles. As detectors, they offer fast response (~100 ps) and can handle high radiation doses (~1 GGy) without degradation. Diamond also offers significant advantages over semiconducting materials as a compact, bi-polar, high voltage switching medium because of its high dielectric strength and thermal conductivity. However, the wide band-gap of diamond and its normally insulating state impose stringent requirements on the trigger radiation that is used to make the diamond conductive. This paper describes a simple model for conduction in diamond, and compares this model with experimental conductivity as measured in a natural diamond Type IIa radiation detector that was irradiated by laser excitation at various wavelengths from 222-353 nm. The DRD geometry consisted of a 3x1x0.5 mm3 Type IIa diamond with metallization on the 3x0.5mm2 sides. The DRD was exposed to laser light in the orthogonal 3x1 mm2 plane. Agreement with the measured data is achieved by fitting a parameter (defined here as β) at the various irradiation wavelengths. This fitting parameter is itself a function of two physical quantities: α, the absorption coefficient of the diamond and ɛo, the ionization cost to produce a hole-pair. Using published values of α, we deduce values of ɛo and compare them with published values for Type IIa diamond in the deep UV to soft x-ray regions. This model also provides a basis for design of high voltage diamond switches that are triggered by near-bandgap (220-250 nm) UV radiation.

  18. Correlation between Sun Protection Factor and Antioxidant Activity, Phenol and Flavonoid Contents of some Medicinal Plants

    PubMed Central

    Ebrahimzadeh, Mohammad Ali; Enayatifard, Reza; Khalili, Masoumeh; Ghaffarloo, Mahdieh; Saeedi, Majid; Yazdani Charati, Jamshid

    2014-01-01

    Long exposure of UV radiation increases risk of skin diseases such as cancer and photoallergic reactions. UV-B (280-320 nm) radiation is mainly responsible for inducing the skin problems. Skin protection is a suitable method against ultraviolet radiation-induced damage. Various synthetic agents have been used as photo protective but because of their potential toxicity in humans, they have limited usage. Natural substances have been recently considered as potential sunscreen resources due to their absorption in the UV region and their antioxidant activity. In the present study, the UV protective effects of 20 extracts from four common medicinal plants were evaluated. Their phenol and flavonoid contents and antioxidant activities were determined and correlation between SPF and these contents were evaluated. SPFs were between 0.102 and 24.470. The highest value was reached with ultrasonic extract of Crataegus pentagyna (SPF = 24.47) followed by methanolic extract of Feijoa sellowiana (SPF = 1.30). Good correlation was found between SPF and phenolic contents (Correlation Coefficient = 0.55 and p = 0.01) but no correlations were found between SPF and flavonoid contents or antioxidant activity. These extracts can be used alone or as additives in other sun screen formulations to enhance their SPF. PMID:25276206

  19. Correlation between Sun Protection Factor and Antioxidant Activity, Phenol and Flavonoid Contents of some Medicinal Plants.

    PubMed

    Ebrahimzadeh, Mohammad Ali; Enayatifard, Reza; Khalili, Masoumeh; Ghaffarloo, Mahdieh; Saeedi, Majid; Yazdani Charati, Jamshid

    2014-01-01

    Long exposure of UV radiation increases risk of skin diseases such as cancer and photoallergic reactions. UV-B (280-320 nm) radiation is mainly responsible for inducing the skin problems. Skin protection is a suitable method against ultraviolet radiation-induced damage. Various synthetic agents have been used as photo protective but because of their potential toxicity in humans, they have limited usage. Natural substances have been recently considered as potential sunscreen resources due to their absorption in the UV region and their antioxidant activity. In the present study, the UV protective effects of 20 extracts from four common medicinal plants were evaluated. Their phenol and flavonoid contents and antioxidant activities were determined and correlation between SPF and these contents were evaluated. SPFs were between 0.102 and 24.470. The highest value was reached with ultrasonic extract of Crataegus pentagyna (SPF = 24.47) followed by methanolic extract of Feijoa sellowiana (SPF = 1.30). Good correlation was found between SPF and phenolic contents (Correlation Coefficient = 0.55 and p = 0.01) but no correlations were found between SPF and flavonoid contents or antioxidant activity. These extracts can be used alone or as additives in other sun screen formulations to enhance their SPF. PMID:25276206

  20. Effector and suppressor circuits of the immune response are activated in vivo by different mechanisms.

    PubMed

    Okamoto, H; Kripke, M L

    1987-06-01

    The application of fluorescein isothiocyanate (FITC) onto the skin of mice induces a contact hypersensitivity immune response. Lymph nodes draining the skin painted with FITC contain fluorescent cells that induce contact hypersensitivity to FITC when injected into normal mice. The antigen-presenting cells responsible for activating the effector pathway of the contact hypersensitivity response express Ia histocompatibility determinants and are resistant to inactivation with gamma-radiation. Exposing the skin to low doses of UV radiation (280-320 nm) before the application of FITC suppresses the contact hypersensitivity response to FITC. Cells present in the draining lymph nodes of these mice induce suppressor T lymphocytes when injected into normal recipients. The inducer cells in the draining lymph nodes are Thy 1+, Ia- and are inactivated by gamma-radiation. These studies demonstrate that different mechanisms are involved in the in vivo activation of effector and suppressor immune responses, and they suggest that the mode of initial antigen presentation determines which immunologic circuit will be activated in response to a contact-sensitizing antigen. PMID:2884661

  1. Joint Effect of Solar UVB and Heat Stress on the Seasonal Change of Egg Hatching Success in the Herbivorous False Spider Mite (Acari: Tenuipalpidae).

    PubMed

    Sudo, M; Osakabe, M

    2015-12-01

    Seasonal population dynamics of an herbivorous mite has been documented in terms of the relationship between thermoresponses and temporal biological factors such as resource availability or predation risk. Although recent studies emphasize the deleterious effects of solar ultraviolet-B (UVB; 280-320nm wavelengths) radiation on plant-dwelling mites, how UVB affects mite population remains largely unknown. On a wild shrub Viburnum erosum var. punctatum in Kyoto, an herbivorous false spider mite, Brevipalpus obovatus Donnadieu, occurs only in autumn. Females of this species lay one-third of their eggs on upper leaf surfaces. Oviposition on upper surfaces is beneficial for avoiding predation by phytoseiids, but exposes eggs to solar UVB and heat stress. To test the hypothesis that the seasonal occurrence of this mite is determined by interactions between solar UVB radiation and temperature, we examined variation in egg hatching success under near-ambient and UV-attenuated sunlight conditions from spring to autumn. The UV-attenuation significantly improved hatching success. However, most eggs died under heat stress regardless of UV treatments in July and August. We established a deterministic heat stress-cumulative UVB dose-egg hatching success response model, which we applied to meteorological data. The model analyses illustrated lower and higher survivability peaks in late May and October, respectively, which partly corresponded to data for annual field occurrence, indicating the importance of solar UVB radiation and heat stress as determinants of the seasonal occurrence of this mite. PMID:26314033

  2. Effector and suppressor circuits of the immune response are activated in vivo by different mechanisms

    SciTech Connect

    Okamoto, H.; Kripke, M.L.

    1987-06-01

    The application of fluorescein isothiocyanate (FITC) onto the skin of mice induces a contact hypersensitivity immune response. Lymph nodes draining the skin painted with FITC contain fluorescent cells that induce contact hypersensitivity to FITC when injected into normal mice. The antigen-presenting cells responsible for activating the effector pathway of the contact hypersensitivity response express Ia histocompatibility determinants and are resistant to inactivation with gamma-radiation. Exposing the skin to low doses of UV radiation (280-320 nm) before the application of FITC suppresses the contact hypersensitivity response to FITC. Cells present in the draining lymph nodes of these mice induce suppressor T lymphocytes when injected into normal recipients. The inducer cells in the draining lymph nodes are Thy 1+, Ia- and are inactivated by gamma-radiation. These studies demonstrate that different mechanisms are involved in the in vivo activation of effector and suppressor immune responses, and they suggest that the mode of initial antigen presentation determines which immunologic circuit will be activated in response to a contact-sensitizing antigen.

  3. Quantifying the inversion accuracy of simplified physical models for the nighttime OI 135.6 nm emission

    NASA Astrophysics Data System (ADS)

    Qin, Jianqi; Kamalabadi, Farzad; Makela, Jonathan J.

    2016-06-01

    A comprehensive statistical analysis is performed to investigate the effects of plasma and neutral density variability on the OI 135.6 nm emission in the nighttime ionosphere. Typical and extreme cases obtained from climatological models are incorporated into a radiative transfer model recently developed by Qin et al. (2015) to systematically quantify the production and loss of the nighttime 135.6 nm emission, as well as to understand their dependence on the ionospheric and thermospheric conditions. It is shown that mutual neutralization can contribute ˜8%-40% of the 135.6 nm emission. Radiative transfer effects due to scattering and absorption reduce the peak brightness measured from a satellite platform in the limb direction by ˜0.3% to 22%. The reduction is more significant for a larger observing zenith angle, typically by ˜45% for lines of sight that go through altitudes below ˜150 km. Furthermore, inversion results show that ignoring radiative transfer effects lead to a maximum ˜12% underestimation of the NmF2, while ignoring mutual neutralization leads to a maximum ˜30% overestimation of the NmF2. In the presence of measurement noise, the estimation accuracy decreases with a decreasing signal-to-noise ratio, and the errors introduced by simplified physical models lead to a significant bias in the inversion results.

  4. CW light sources at the 589 nm sodium D2 line by sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Lu, J.; Xu, L. J.; Sun, G. C.; Zhao, Z. M.; Gao, X.; Lin, J. Q.

    2010-10-01

    We present a laser architecture to obtain continuous-wave (CW) light sources at the 589 nm sodium D2 line. A 808 nm diode-pumped a Nd:YLiF4 (Nd:YLF) crystal emitting at 1053 nm. A part of the pump power was then absorbed by the Nd:YLF crystal. The remaining was used to pump a Nd:YAG crystal emitting at 1338 nm. Intracavity sum-frequency mixing at 1053 and 1338 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 235 mW at 589 nm with a pump laser diode emitting 17.8 W at 808 nm.

  5. SASE free electron lasers as short wavelength coherent sources. From first results at 100 nm to a 1 Å X-ray laser

    NASA Astrophysics Data System (ADS)

    Treusch, R.; Feldhaus, J.

    2003-10-01

    During the last few years free electron lasers (FELs) based on self-amplified spontaneous emission (SASE) have been demonstrated at wavelengths of 12 μm [CITE], 830 nm [CITE], 530 nm [CITE] and 385 nm [CITE], and around 100 nm [CITE]. Recently, saturation has been observed in the vacuum ultraviolet (VUV) spectral region between 82 nm and 125 nm at the TESLA Test Facility (TTF) at DESY. The radiation pulses have been characterized with respect to pulse energy, statistical fluctuations, angular divergence and spectral distribution, both in the linear gain and in the saturation regime of the FEL [CITE]. The results are in good agreement with theoretical simulations, providing a solid basis for other projects aiming at still shorter wavelengths down to the 0.1 nm range [CITE].

  6. An efficient continuous-wave 591 nm light source based on sum-frequency mixing of a diode pumped Nd:GdVO4-Nd:CNGG laser

    NASA Astrophysics Data System (ADS)

    Zhao, Y. D.; Liu, J. H.

    2013-08-01

    We report a laser architecture to obtain continuous-wave (CW) yellow-orange light sources at the 591 nm wavelength. An 808 nm diode pumped a Nd:GdVO4 crystal emitting at 1063 nm. A part of the pump power was then absorbed by the Nd:CNGG crystal. The remaining pump power was used to pump a Nd:CNGG crystal emitting at 1329 nm. Intracavity sum-frequency mixing at 1063 and 1329 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 494 mW at 591 nm with a pump laser diode emitting 17.8 W at 808 nm.

  7. Radiation Therapy

    MedlinePlus

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from ... half of all cancer patients receive it. The radiation may be external, from special machines, or internal, ...

  8. Radiation therapy

    MedlinePlus

    Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. ... faster than normal cells in the body. Because radiation is most harmful to quickly growing cells, radiation ...

  9. Radiation Therapy

    MedlinePlus

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them ... places inside your body. The type of radiation therapy you receive depends on many factors, including The ...

  10. Radiation Therapy

    MedlinePlus

    ... people who have radiation therapy may feel more tired than usual, not feel hungry, or lose their ... of radiation therapy include: Fatigue. Fatigue, or feeling tired, is the most common side effect of radiation ...

  11. Radiation Emergencies

    MedlinePlus

    ... day from sources such as sunlight. A radiation emergency would involve larger amounts of radiation and could ... are no guarantees of safety during a radiation emergency, you can take actions to protect yourself. You ...

  12. Novel high refractive index fluids for 193nm immersion lithography

    NASA Astrophysics Data System (ADS)

    Santillan, Julius; Otoguro, Akihiko; Itani, Toshiro; Fujii, Kiyoshi; Kagayama, Akifumi; Nakano, Takashi; Nakayama, Norio; Tamatani, Hiroaki; Fukuda, Shin

    2006-03-01

    Despite the early skepticism towards the use of 193-nm immersion lithography as the next step in satisfying Moore's law, it continuous to meet expectations on its feasibility in achieving 65-nm nodes and possibly beyond. And with implementation underway, interest in extending its capability for smaller pattern sizes such as the 32-nm node continues to grow. In this paper, we will discuss the optical, physical and lithographic properties of newly developed high index fluids of low absorption coefficient, 'Babylon' and 'Delphi'. As evaluated in a spectroscopic ellipsometer in the 193.39nm wavelength, the 'Babylon' and 'Delphi' high index fluids were evaluated to have a refractive index of 1.64 and 1.63 with an absorption coefficient of 0.05/cm and 0.08/cm, respectively. Lithographic evaluation results using a 193-nm 2-beam interferometric exposure tool show the imaging capability of both high index fluids to be 32-nm half pitch lines and spaces.

  13. Temperature characteristic of 808nm VCSELs with large aperture

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Feng, Dawei; Hao, Yongqin; Wang, Yong; Yan, Changling; Lu, Peng; Li, Yang

    2015-03-01

    In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/°, the thermal resistance is 0.098°/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.

  14. [Influence of cold spot temperature on 253.7 nm resonance spectra line of electrodeless discharge lamps].

    PubMed

    Dong, Jin-yang; Zhang, Gui-xin; Wang, Chang-quan

    2012-01-01

    As a kind of new electric light source, electrodeless discharge lamps are of long life, low mercury and non-stroboscopic light. The lighting effect of electrodeless discharge lamps depends on the radiation efficiency of 253.7 nm resonance spectra line to a large extent. The influence of cold temperature on 253.7 nm resonance spectra line has been studied experimentally by atomic emission spectral analysis. It was found that the radiation efficiency of 253.7 nm resonance spectra line is distributed in a nearly normal fashion with the variation of cold spot temperature, in other words, there is an optimum cold spot temperature for an electrodeless discharge lamp. At last, the results of experiments were analyzed through gas discharge theory, which offers guidance to the improvement of lighting effect for electrodeless discharge lamps. PMID:22497125

  15. Segmentation of the macular choroid in OCT images acquired at 830nm and 1060nm

    NASA Astrophysics Data System (ADS)

    Lee, Sieun; Beg, Mirza F.; Sarunic, Marinko V.

    2013-06-01

    Retinal imaging with optical coherence tomography (OCT) has rapidly advanced in ophthalmic applications with the broad availability of Fourier domain (FD) technology in commercial systems. The high sensitivity afforded by FD-OCT has enabled imaging of the choroid, a layer of blood vessels serving the outer retina. Improved visualization of the choroid and the choroid-sclera boundary has been investigated using techniques such as enhanced depth imaging (EDI), and also with OCT systems operating in the 1060-nm wavelength range. We report on a comparison of imaging the macular choroid with commercial and prototype OCT systems, and present automated 3D segmentation of the choroid-scleral layer using a graph cut algorithm. The thickness of the choroid is an important measurement to investigate for possible correlation with severity, or possibly early diagnosis, of diseases such as age-related macular degeneration.

  16. Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

    NASA Astrophysics Data System (ADS)

    Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

    2016-04-01

    5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

  17. Atmospheric radiation

    SciTech Connect

    Harshvardhan, M.R. )

    1991-01-01

    Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

  18. 40nm tunable multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Qingsong; Wang, Tianshu; Zhang, Peng; Dong, Keyan; Jiang, Huilin

    2014-12-01

    A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier (EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

  19. 7nm logic optical lithography with OPC-Lite

    NASA Astrophysics Data System (ADS)

    Smayling, Michael C.; Tsujita, Koichiro; Yaegashi, Hidetami; Axelrad, Valery; Nakayama, Ryo; Oyama, Kenichi; Yamauchi, Shohei; Ishii, Hiroyuki; Mikami, Koji

    2015-03-01

    The CMOS logic 22nm node was the last one done with single patterning. It used a highly regular layout style with Gridded Design Rules (GDR). Smaller nodes have required the same regular layout style but with multiple patterning for critical layers. A "line/cut" approach is being used to achieve good pattern fidelity and process margin.[1] As shown in Fig. 1, even with "line" patterns, pitch division will eventually be necessary. For the "cut" pattern, Design-Source-Mask Optimization (DSMO) has been demonstrated to be effective at the 20nm node and below.[2,3,4] Single patterning was found to be suitable down to 16nm, while double patterning extended optical lithography for cuts to the 10-12nm nodes. Design optimization avoided the need for triple patterning. Lines can be patterned with 193nm immersion with no complex OPC. The final line dimensions can be achieved by applying pitch division by two or four.[5] In this study, we extend the scaling using simplified OPC to the 7nm node for critical FEOL and BEOL layers. The test block is a reasonably complex logic function with ~100k gates of combinatorial logic and flip-flops, scaled from previous experiments. Simulation results show that for cuts at 7nm logic dimensions, the gate layer can be done with single patterning whose minimum pitch is 53nm, possibly some of the 1x metal layers can be done with double patterning whose minimum pitch is 53nm, and the contact layer will require triple patterning whose minimum pitch is 68nm. These pitches are less than the resolution limit of ArF NA=1.35 (72nm). However these patterns can be separated by a combination of innovative SMO for less than optical resolution limit and a process trick of hole-repair technique. An example of triple patterning coloring is shown in Fig 3. Fin and local interconnect are created by lines and trims. The number of trim patterns are 3 times (min. pitch=90nm) and twice (min. pitch=120nm), respectively. The small number of masks, large pitches, and

  20. Polarization-dependent aluminum metasurface operating at 450 nm.

    PubMed

    Højlund-Nielsen, Emil; Zhu, Xiaolong; Carstensen, Marcus S; Sørensen, Michael K; Vannahme, Christoph; Asger Mortensen, N; Kristensen, Anders

    2015-11-01

    We report on a polarization-dependent plasmonic aluminum-based high-density metasurface operating at blue wavelengths. The fabricated sub-wavelength structures, tailored in size and geometry, possess strong, localized, plasmonic resonances able to control linear polarization. Best performance is achieved by rotating an elongated rectangular structure of length 180 nm and width 110 nm inside a square lattice of period 250 nm. In the case of 45 degrees rotation of the structure with respect to the lattice, the normal-incidence reflectance drops around the resonance wavelength of 457 nm from about 60 percent to below 2 percent. PMID:26561151

  1. The Influence of Water Vapor Absorption in the 290-350 nm Region on Solar Irradiance: Laboratory Studies and Model Simulation

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Du, J.; Huang, L.; Min, Q.

    2015-12-01

    Water vapor is the most abundant greenhouse gas in the earth's atmosphere. Absorption of the solar radiation by water vapor in the near UV region may partially account for the up to 30% discrepancy between the modeled and the observed solar energy absorbed by the atmosphere. But the magnitude of water vapor absorption in the near UV region at wavelengths shorter than 384 nm was not known prior to this study. We have determined absorption cross sections of water vapor at 5 nm intervals in the 290-350 nm region, by using cavity ring-down spectroscopy. Water vapor cross section values range from 2.94×10-24 to 2.13×10-25 cm2/molecule in the wavelength region studied. The effect of the water vapor absorption in the 290-350 nm region on the modeled radiation flux at the ground level has been evaluated using radiative transfer model.

  2. Development of a metrology to characterize EUV optics at 13.5nm

    NASA Astrophysics Data System (ADS)

    Vongehr, Monika; Predehl, Peter; Hasinger, Günter

    2006-04-01

    Light sources, focusing elements and detectors working at wavelengths from 5nm to 40nm, so called EUV, are of increasing interest for the semiconductor industry, especially for lithography. A metrology has been developed to characterize modified nested Wolter grazing incidence optics which act as the condenser optic. It consists of a monochromatic EUV source and a MCP detector. The EUV source is designed to emit radiation at a wavelength of 13.5nm into a solid angle of up to 1.8sr, which is realized by a silicon-zirconium target used in transmission. Detector and EUV source have been calibrated. In particular, the angular dependences of the source radiation and the detector efficiency have been investigated. The calibrated metrology could be used for measuring the imaging properties of modified nested Wolter optics revealing the point-spread function (psf), the focal length and the effective collecting area. In this paper we will report on experimental setup in the X-ray test facility "PUMA," developing the EUV source, multi-channel plate detector properties, and the results of testing a modified EUV optics.

  3. Radiation Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Mihalas, Dimitri

    Basic Radiation Theory Specific Intensity Photon Number Density Photon Distribution Function Mean Intensity Radiation Energy Density Radiation Energy Flux Radiation Momentum Density Radiation Stress Tensor (Radiation Pressure Tensor) Thermal Radiation Thermodynamics of Thermal Radiation and a Perfect Gas The Transfer Equation Absorption, Emission, and Scattering The Equation of Transfer Moments of the Transfer Equation Lorentz Transformation of the Transfer Equation Lorentz Transformation of the Photon 4-Momentum Lorentz Transformation of the Specific Intensity, Opacity, and - Emissivity Lorentz Transformation of the Radiation Stress Energy Tensor The Radiation 4-Force Density Vector Covariant Form of the Transfer Equation Inertial-Frame Equations of Radiation Hydrodynamics Inertial-Frame Radiation Equations Inertial-Frame Equations of Radiation Hydrodynamics Comoving-Frame Equation of Transfer Special Relativistic Derivation (D. Mihalas) Consistency Between Comoving-Frame and Inertial-Frame Equations Noninertial Frame Derivation (J. I. Castor) Analysis of O (v/c) Terms Lagrangian Equations of Radiation Hydrodynamics Momentum Equation Gas Energy Equation First Law of Thermodynamics for the Radiation Field First Law of Thermodynamics for the Radiating Fluid Mechanical Energy Equation Total Energy Equation Consistency of Different Forms of the Radiating-Fluid Energy - and Momentum Equations Consistency of Inertial-Frame and Comoving-Frame Radiation Energy - and Momentum Equations Radiation Diffusion Radiation Diffusion Nonequilibrium Diffusion The Problem of Flux Limiting Shock Propagation: Numerical Methods Acoustic Waves Numerical Stability Systems of Equations Implications of Shock Development Implications of Diffusive Energy Transport Illustrative Example Numerical Radiation Hydrodynamics Radiating Fluid Energy and Momentum Equations Computational Strategy Energy Conservation Formal Solution Multigroup Equations An Astrophysical Example Adaptive-Grid Radiation

  4. Photodissociation dynamics of 2-nitropropane and 2-methyl-2-nitropropane at 248 and 193 nm.

    PubMed

    Sengupta, Sumana; Indulkar, Yogesh; Kumar, Awadhesh; Dhanya, Suresh; Naik, Prakash Dattatray; Bajaj, Parma Nand

    2008-12-11

    Dynamics of formation of electronically excited NO2 and formation of OH fragment, during photo dissociation of 2-nitropropane (NP) and 2-methyl-2-nitropropane (MNP), were investigated at 193 and 248 nm. The radiative lifetime of the electronically excited NO2 fragment, observed at 193 nm, was measured to be 1.2 ( 0.1 micros and the rate coefficient of quenching of its emission by MNP was measured as (2.7 ( 0.1) x 10(-10) molecule(-1) cm3 s(-1). Formation of the ground electronic state of OH was confirmed in both molecules. State selective laser induced fluorescence technique was used to detect the nascent OH (X 2Pi, v'', J'') fragments in different ro-vibrational states, and to obtain information on energy partitioning. Though MNP and NP differ in the types of the available H atoms, the dynamics of OH formation is found to be the same in both. The relative population in different rotational states does not follow Boltzmann equilibrium distribution in both the molecules at 193 and 248 nm. The translational energies of the OH fragments, calculated from the Doppler width, are 21.2 ( 7.2 and 25.0 ( 2.5 kcal mol-1 for NP at 248 and 193 nm, respectively. The translational energies of the OH fragments, in the case of MNP, are found to be lower, 17.5 ( 4.1 and 22.0 ( 3.2 kcal mol-1,respectively, at 248 nm 193 nm. These results are compared with the earlier reports on photodissociation of nitromethane (NM), nitroethane (NE), and other nitroalkanes. All possible dissociation pathways of these molecules--NM, NE, NP, and MNPs leading to the formation of the OH fragment were investigated computationally, with geometry optimization at the B3LYP/6-311+G(d,p) level and energy calculation at the MP4(SDQ)/6-311+G (d,p) level. The results suggest that in NM, OH is formed after isomerization to CH2N(OH)O, whereas in all other cases OH is formed from HONO, a primary product of molecular elimination of nitroalkanes, formed with sufficient internal energy. PMID:19053556

  5. The degradation of alzak by short wavelength ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Donohoe, M. J.; Mcintosh, R., Jr.; Henninger, J. H.

    1972-01-01

    The changes in reflectance of thermal aluminum coating samples exposed to different irradiating utraviolet wavelengths are discussed. It is shown that the coating is damaged faster and further by 180 to 210 in radiation than by Lyman alpha radiation. On an equivalent incident energy basis, Lyman alpha does less damage than 180 to 210 nm radiation. Above 300 nm no degradation is observed for long exposures and below 300 nm increasing degradation with decreasing wavelength is found. It is concluded that Lyman alpha radiation need not be included in laboratory testing of this thermal coating for spacecraft structures.

  6. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    NASA Astrophysics Data System (ADS)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760

  7. Quantifying solar spectral irradiance in aquatic habitats for the assessment of photoenhanced toxicity

    USGS Publications Warehouse

    Barron, M.G.; Little, E.E.; Calfee, R.; Diamond, S.

    2000-01-01

    The spectra and intensity of solar radiation (solar spectral irradiance [SSI]) was quantified in selected aquatic habitats in the vicinity of an oil field on the California coast. Solar spectral irradiance measurements consisted of spectral scans (280-700 rim) and radiometric measurements of ultraviolet (UV): UVB (280-320 nm) and UVA (320-400 nm). Solar spectral irradiance measurements were taken at the surface and at various depths in two marsh ponds, a shallow wetland, an estuary lagoon, and the intertidal area of a high-energy sandy beach. Daily fluctuation in SSI showed a general parabolic relationship with time; maximum structure-activity relationship (SAR) was observed at approximate solar noon. Solar spectral irradiance measurements taken at 10-cm depth at approximate solar noon in multiple aquatic habitats exhibited only a twofold variation in visible light and UVA and a 4.5-fold variation in UVB. Visible light ranged from 11,000 to 19,000 ??W/cm2, UVA ranged from 460 to 1,100 ??W/cm2, and UVB ranged from 8.4 to 38 ??W/cm2. In each habitat, the attenuation of light intensity with increasing water depth was differentially affected over specific wavelengths of SSI. The study results allowed the development of environmentally realistic light regimes necessary for photoenhanced toxicity studies.

  8. Spectral emission properties of a LPP light source in the sub-200nm range for wafer inspection applications

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Hudgins, Duane; Abhari, Reza; Abreau, F.

    2015-03-01

    In this work, the spectral emission proprieties of a droplet-based laser-produced plasma are investigated in the VUV range. These studies are performed with a spectrograph operating from 30 nm to 180 nm at a spectral resolution of 0.1 nm. The emission spectra are recorded for different droplet-based metal fuels such as tin, indium and gallium in the presence of different background gas pressure levels. The experimental results are relevant for alternative light sources that would be needed for future wafer inspection tools. In addition, the experimental results help to determine the Out- Of-Band (OOB) radiation emission of the EUV source. By tuning the type of fuel, the laser energies and the background gas, the LPP light source shows good capabilities to be operated as a tunable light source that covers a spectral emission range from the EUV to the sub-200 nm range.

  9. 500.5-nm blue-green laser based on sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Na, Y. X.

    2011-07-01

    We report for the first time a continuous-wave (CW) coherent radiation at 500.5 nm by intracavity sum-frequency generation of 1063 nm Nd:GdVO4 laser and 946 nm Nd:YAG laser. Blue-green laser is obtained by using a doubly cavity, type-II critical phase matching KTiOPO4 (KTP) crystal sum-frequency mixing. With total pump power of 27.8 W, TEM00 mode blue-green laser at 500.5 nm of 421 mW is obtained. At the output power level of 421 mW, the blue-green power stability is better than 2.8% and laser beam quality M 2 factor is 1.37.

  10. Electric Field-Assisted Photochemical Water Splitting Should Operate with 287 nm Light.

    PubMed

    Bachler, Vinzenz; Gärtner, Wolfgang

    2016-05-01

    The major photoreaction of water is the homolytic splitting of one O-H bond starting from the 1(1) B1 excited state (λmax = 167 nm). This reaction produces H• and •OH radicals. The combination of two H• atoms leads to the potential energy carrier dihydrogen. However, the energy required to obtain the photoreactive 1(1) B1 electronic state is about 7.4 eV, which cannot be effectively provided by solar radiation. The sun light spectrum on earth comprises the visible and ultraviolet region, but shows vanishing intensity near 7 eV (177.1 nm). This work provides theoretical evidence that the photoreactive 1(1) B1 state of water can be shifted into the ultraviolet (UV-B) light region (≈287 nm) by including explicitly an electric field in the calculations of the water absorption spectrum. To accomplish such bathochromic shift, a large field strength of 3.08 VÅ(-1) is required. The field-dependent excitation energies were calculated by applying the symmetry-adapted cluster configuration interaction (SAC-CI) procedure. Based on this theoretical analysis, we propose that photochemical water splitting can be accomplished by means of 287 nm light provided the water molecule is favorably oriented by an external electric field and is subsequently activated by a reversal of the field orientation. PMID:26876336

  11. Solar Spectral Irradiance at 782 nm as Measured by the SES Sensor Onboard Picard

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki, S.; Damé, L.; Bolsée, D.; Pereira, N.

    2016-04-01

    Picard is a satellite dedicated to the simultaneous measurement of the total and solar spectral irradiance, the solar diameter, the solar shape, and to the Sun's interior through the methods of helioseismology. The satellite was launched on June 15, 2010, and pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the satellite. The SES sensor produced an image of the Sun at 782 ± 2.5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782 nm from 2010 to 2014. During this period of Solar Cycle 24, the amplitude of the changes has been of the order of ± 0.08 %, corresponding to a range of about 2× 10^{-3} W m^{-2} nm^{-1}. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm. SES data show similar amplitude variations with the semi-empirical model Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S), whereas the Spectral Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and Climate Experiment satellite (SORCE) highlights higher amplitudes.

  12. 1319 nm and 1356 nm dual-wavelength operation of diode-side-pumped Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Wang, Zhi-chao; Zhang, Shen-jin; Yang, Feng; Zhang, Feng-feng; Yuan, Lei; He, Miao; Li, Jia-jia; Zhang, Xiao-wen; Zong, Nan; Wang, Zhi-min; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2016-05-01

    We report the first demonstration on a diode-side-pumped quasi continuous wave (QCW) dual-wavelength Nd:YAG laser operating at 1319 nm and 1356 nm. The resonator adopts symmetrical L-shaped flat-flat structure working in a thermally near unstable cavity. By precise coating on the cavity mirrors, the simultaneous oscillation at 1319 nm and 1356 nm is delivered. A maximum dual-wavelength output power of 9.4 W is obtained. The beam quality factor M2 is measured to be 1.9.

  13. Evaluation of dental pulp repair using low level laser therapy (688 nm and 785 nm) morphologic study in capuchin monkeys

    NASA Astrophysics Data System (ADS)

    Pretel, H.; Oliveira, J. A.; Lizarelli, R. F. Z.; Ramalho, L. T. O.

    2009-02-01

    The aim of this study was to evaluate the hypothesis that low-level laser therapy (LLLT) 688 nm and 785 nm accelerate dentin barrier formation and repair process after traumatic pulp exposure. The sample consisted of 45 premolars of capuchin monkeys (Cebus apella) with pulp exposure Class V cavities. All premolars were treated with calcium hydroxide (Ca(OH)2), divided in groups of 15 teeth each, and analyzed on 7th, 25th, and 60th day. Group GI - only Ca(OH)2, GII - laser 688 nm, and GIII - laser 785 nm. Laser beam was used in single and punctual dose with the parameters: continuous, 688 nm and 785 nm wavelength, tip's area of 0.00785 cm2, power 50 mW, application time 20 s, dose 255 J/cm2, energy 2 J. Teeth were capped with Ca(OH)2, Ca(OH)2 cement and restored with amalgam. All groups presented pulp repair. On 25th day the thickness of the formed dentin barrier was different between the groups GI and GII (p < 0.05) and between groups GI and GIII (p < 0.01). On 60th day there was difference between GI and GIII (p < 0.01). It may be concluded that, LLLT 688 nm and 785 nm accelerated dentin barrier formation and consequently pulp repair process, with best results using infrared laser 785 nm.

  14. Demonstration of miniaturized 20mW CW 280nm and 266nm solid-state UV laser sources

    NASA Astrophysics Data System (ADS)

    Landru, Nicolas; Georges, Thierry; Beaurepaire, Julien; Le Guen, Bruno; Le Bail, Guy

    2015-02-01

    Visible 561 nm and 532 nm laser emissions from 14-mm long DPSS monolithic cavities are frequency converted to deep UV 280 nm and 266 nm in 16-mm long monolithic external cavities. Wavelength conversion is fully insensitive to mechanical vibrations and the whole UV laser sources fit in a miniaturized housing. More than 20 mW deep UV laser emission is demonstrated with high power stability, low noise and good beam quality. Aging tests are in progress but long lifetimes are expected thanks to the cavity design. Protein detection and deep UV resonant Raman spectroscopy are applications that could benefit from these laser sources.

  15. Model-based scattering bars implementation for 65nm and 45nm nodes using IML technology

    NASA Astrophysics Data System (ADS)

    Hsu, Michael; Van Den Broeke, Doug; Laidig, Tom; Wampler, Kurt E.; Hollerbach, Uwe; Socha, Robert; Chen, J. F.; Hsu, Stephen; Shi, Xuelong

    2005-06-01

    Scattering Bars (SB) OPC, together with optimized illumination, is no doubt one of the critical enablers for low k1 lithography manufacturing. The manufacturing implementation of SB so far has been mainly based on rule-based approach. While this has been working well, a more effective model-based approach is much more desired lithographically for manufacturing at 65nm and 45nm nodes. This is necessary to ensure sufficient process margin using hyper NA for patterning random IC design. In our model-based SB (M-SB) OPC implementation, we have based on the patented IML Technology from ASML MaskTools. In this report, we use both dark field contact hole and clear field poly gate mask to demonstrate this implementation methodology. It is also quite applicable for dark field trench masks, such as local interconnect mask with damascene metal. For our full-chip implementation flow, the first step is to determine the critical design area and then to proceed with NA and illumination optimization. We show that, using LithoCruiser, we are able to select the best NA in combination with optimum illumination via a Diffraction Optical Element (DOE). The decision to use a custom DOE or one from the available DOE library from ASML can be made based on predicted process performance and cost effectiveness. With optimized illumination, it is now possible to construct an interference map for the full-chip mask pattern. Utilizing the interference map, M-SB OPC is generated. Next, model OPC can be applied with the presence of M-SB for the entire chip. It is important to note here, that from our experience, the model OPC must be calibrated with the presence of SB in order to achieve the desired accuracy. We report the full-chip processing benchmark using MaskWeaver to apply both M-SB and model OPC. For actual patterning performance, we have verified the full chip OPC treatment using SLiC, a DFM tool from Cadence. This implementation methodology can be applied to binary chrome mask

  16. Pelvic radiation - discharge

    MedlinePlus

    Radiation of the pelvis - discharge; Cancer treatment - pelvic radiation; Prostate cancer - pelvic radiation; Ovarian cancer - pelvic radiation; Cervical cancer - pelvic radiation; Uterine cancer - pelvic radiation; Rectal cancer - ...

  17. Method for radiation detection and measurement

    DOEpatents

    Miller, Steven D.

    1993-01-01

    Dose of radiation to which a body of crystalline material has been exposed is measured by exposing the body to optical radiation at a first wavelength, which is greater than about 540 nm, and measuring optical energy emitted from the body by luminescence at a second wavelength, which is longer than the first wavelength.

  18. Method for radiation detection and measurement

    DOEpatents

    Miller, S.D.

    1993-12-21

    Dose of radiation to which a body of crystalline material has been exposed is measured by exposing the body to optical radiation at a first wavelength, which is greater than about 540 nm, and measuring optical energy emitted from the body by luminescence at a second wavelength, which is longer than the first wavelength. 9 figures.

  19. Electron beam inspection of 16nm HP node EUV masks

    NASA Astrophysics Data System (ADS)

    Shimomura, Takeya; Narukawa, Shogo; Abe, Tsukasa; Takikawa, Tadahiko; Hayashi, Naoya; Wang, Fei; Ma, Long; Lin, Chia-Wen; Zhao, Yan; Kuan, Chiyan; Jau, Jack

    2012-11-01

    EUV lithography (EUVL) is the most promising solution for 16nm HP node semiconductor device manufacturing and beyond. The fabrication of defect free EUV mask is one of the most challenging roadblocks to insert EUVL into high volume manufacturing (HVM). To fabricate and assure the defect free EUV masks, electron beam inspection (EBI) tool will be likely the necessary tool since optical mask inspection systems using 193nm and 199nm light are reaching a practical resolution limit around 16nm HP node EUV mask. For production use of EBI, several challenges and potential issues are expected. Firstly, required defect detection sensitivity is quite high. According to ITRS roadmap updated in 2011, the smallest defect size needed to detect is about 18nm for 15nm NAND Flash HP node EUV mask. Secondly, small pixel size is likely required to obtain the high sensitivity. Thus, it might damage Ru capped Mo/Si multilayer due to accumulated high density electron beam bombardments. It also has potential of elevation of nuisance defects and reduction of throughput. These challenges must be solved before inserting EBI system into EUV mask HVM line. In this paper, we share our initial inspection results for 16nm HP node EUV mask (64nm HP absorber pattern on the EUV mask) using an EBI system eXplore® 5400 developed by Hermes Microvision, Inc. (HMI). In particularly, defect detection sensitivity, inspectability and damage to EUV mask were assessed. As conclusions, we found that the EBI system has capability to capture 16nm defects on 64nm absorber pattern EUV mask, satisfying the sensitivity requirement of 15nm NAND Flash HP node EUV mask. Furthermore, we confirmed there is no significant damage to susceptible Ru capped Mo/Si multilayer. We also identified that low throughput and high nuisance defect rate are critical challenges needed to address for the 16nm HP node EUV mask inspection. The high nuisance defect rate could be generated by poor LWR and stitching errors during EB writing

  20. Hard X-ray Microscopy with sub 30 nm Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Tang, Mau-Tsu; Song, Yen-Fang; Yin, Gung-Chian; Chen, Fu-Rong; Chen, Jian-Hua; Chen, Yi-Ming; Liang, Keng S.; Duewer, F.; Yun, Wenbing

    2007-01-01

    A transmission X-ray microscope (TXM) has been installed at the BL01B beamline at National Synchrotron Radiation Research Center in Taiwan. This state-of-the-art TXM operational in a range 8-11 keV provides 2D images and 3D tomography with spatial resolution 60 nm, and with the Zernike-phase contrast mode for imaging light materials such as biological specimens. A spatial resolution of the TXM better than 30 nm, apparently the best result in hard X-ray microscopy, has been achieved by employing the third diffraction order of the objective zone plate. The TXM has been applied in diverse research fields, including analysis of failure mechanisms in microelectronic devices, tomographic structures of naturally grown photonic specimens, and the internal structure of fault zone gouges from an earthquake core. Here we discuss the scope and prospects of the project, and the progress of the TXM in NSRRC.

  1. Hard X-ray Microscopy with sub 30 nm Spatial Resolution

    SciTech Connect

    Tang, M.-T.; Song, Y.-F.; Yin, G.-C.; Chen, J.-H.; Chen, Y.-M.; Liang, Keng S.; Chen, F.-R.; Duewer, F.; Yun Wenbing

    2007-01-19

    A transmission X-ray microscope (TXM) has been installed at the BL01B beamline at National Synchrotron Radiation Research Center in Taiwan. This state-of-the-art TXM operational in a range 8-11 keV provides 2D images and 3D tomography with spatial resolution 60 nm, and with the Zernike-phase contrast mode for imaging light materials such as biological specimens. A spatial resolution of the TXM better than 30 nm, apparently the best result in hard X-ray microscopy, has been achieved by employing the third diffraction order of the objective zone plate. The TXM has been applied in diverse research fields, including analysis of failure mechanisms in microelectronic devices, tomographic structures of naturally grown photonic specimens, and the internal structure of fault zone gouges from an earthquake core. Here we discuss the scope and prospects of the project, and the progress of the TXM in NSRRC.

  2. Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

    SciTech Connect

    Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C.

    2013-04-22

    There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

  3. Demonstration of a GaAs-based 1550-nm continuous wave photomixer

    SciTech Connect

    Zhang, W.-D. Brown, E. R.; Middendorf, J. R.

    2015-01-12

    An Er:GaAs-based 1550-nm CW photomixer is demonstrated. The related mechanism is extrinsic photoconductivity with optical absorption between the localized deep levels created by the Er and the extended states above the conduction band edge of GaAs. With the power boost made possible by a fiber-coupled erbium-doped-fiber amplifier, the Er:GaAs photomixers, operating at 1550 nm, radiate THz power levels easily measured by a Golay cell, and display a power spectrum having a −3 dB roll-off frequency of 307 GHz. This corresponds to a photocarrier lifetime of 520 fs, in good agreement with a previous measurement of the bandwidth of the same material in a photoconductive switch.

  4. Temperature- and pressure-dependent absorption coefficients for CO2 and O2 at 193 nm

    NASA Astrophysics Data System (ADS)

    Hartinger, K. T.; Nord, S.; Monkhouse, P. B.

    Absorption of laser radiation at 193 nm by CO2 and O2 was studied at a series of different temperatures up to 1273 K and pressures up to 1 bar. The spectrum for CO2 was found to be broadband, so that absorption could be fitted to a Beer-Lambert law. On the other hand, the corresponding O2 spectrum is strongly structured and parameterisation requires a more complex relation, depending on both temperature and the product (pressure × absorption path length). In this context, the influence of spectral structure on the resulting spectrally integrated absorption coefficients is discussed. Using the fitting parameters obtained, effective transmissions at 193 nm can be calculated for a wide range of experimental conditions. As an illustration of the practical application of these data, the calculation of effective transmission for a typical industrial flue gas is described.

  5. Next-generation 193-nm laser for sub-100-nm lithography

    NASA Astrophysics Data System (ADS)

    Duffey, Thomas P.; Blumenstock, Gerry M.; Fleurov, Vladimir B.; Pan, Xiaojiang; Newman, Peter C.; Glatzel, Holger; Watson, Tom A.; Erxmeyer, J.; Kuschnereit, Ralf; Weigl, Bernhard

    2001-09-01

    The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with

  6. Scattering matrices of martian dust analogs at 488 nm and 647 nm

    NASA Astrophysics Data System (ADS)

    Dabrowska, Dominika D.; Muñoz, Olga; Moreno, Fernando; Ramos, José L.; Martínez-Frías, Jesús; Wurm, Gerhard

    2015-04-01

    We present measurements of the complete scattering matrix as a function of the scattering angle of five martian dust analogs, namely montmorillonite, two palagonite (JSC-1) samples, basalt, and calcite. The measurements are performed at 488 and 647 nm, covering the scattering angle range from 3° to 177°. The experimental scattering matrices are compared with results of Lorenz-Mie calculations performed for the same size distributions and refractive indices as our analog samples. As expected, we find that scattering matrices of realistic polydispersions of dust particles cannot be replaced by such calculated matrices. In contrast, the measured phase functions for our martian dust analogs may be considered a good approximation for martian dust at the studied wavelengths. Further, because of the sensitivity of polarimetry to particle microphysics, spectro-polarimetric observations from the martian surface appear to be a powerful diagnostic tool to infer the composition of the dust in the martian atmosphere. To facilitate the use of the experimental matrices for multiple-scattering calculations with polarization included, we compute the corresponding synthetic scattering matrices based on the measurements and defined in the full angle range from 0° to 180°.

  7. Tailoring 10 nm scale suspended graphene junctions and quantum dots.

    PubMed

    Tayari, Vahid; McRae, Andrew C; Yiğen, Serap; Island, Joshua O; Porter, James M; Champagne, Alexandre R

    2015-01-14

    The possibility to make 10 nm scale, and low-disorder, suspended graphene devices would open up many possibilities to study and make use of strongly coupled quantum electronics, quantum mechanics, and optics. We present a versatile method, based on the electromigration of gold-on-graphene bow-tie bridges, to fabricate low-disorder suspended graphene junctions and quantum dots with lengths ranging from 6 nm up to 55 nm. We control the length of the junctions, and shape of their gold contacts by adjusting the power at which the electromigration process is allowed to avalanche. Using carefully engineered gold contacts and a nonuniform downward electrostatic force, we can controllably tear the width of suspended graphene channels from over 100 nm down to 27 nm. We demonstrate that this lateral confinement creates high-quality suspended quantum dots. This fabrication method could be extended to other two-dimensional materials. PMID:25490053

  8. High-efficency stable 213-nm generation for LASIK application

    NASA Astrophysics Data System (ADS)

    Wang, Zhenglin; Alameh, Kamal; Zheng, Rong

    2005-01-01

    213nm Solid-state laser technology provides an alternative method to replace toxic excimer laser in LASIK system. In this paper, we report a compact fifth harmonic generation system to generate high pulse energy 213nm laser from Q-switched Nd:YAG laser for LASIK application based on three stages harmonic generation procedures. A novel crystal housing was specifically designed to hold the three crystals with each crystal has independent, precise angular adjustment structure and automatic tuning control. The crystal temperature is well maintained at ~130°C to improve harmonic generation stability and crystal operation lifetime. An output pulse energy 35mJ is obtained at 213nm, corresponding to total conversion efficiency ~10% from 1064nm pump laser. In system verification tests, the 213nm output power drops less than 5% after 5 millions pulse shots and no significant damage appears in the crystals.

  9. Methods to achieve sub-100-nm contact hole lithography

    NASA Astrophysics Data System (ADS)

    Lindsay, Tracy K.; Kavanagh, Robert J.; Pohlers, Gerd; Kanno, Takafumi; Bae, Young C.; Barclay, George G.; Kanagasabapathy, Subbareddy; Mattia, Joseph

    2003-06-01

    There are numerous methods being explored by lithographers to achieve contact holes below 100nm. Regarding optical impact on contact hole imaging, very high numerical aperture tools are becoming available at 193nm (as high as 0.9) and various optical extension techniques such as assist features, focus drilling, phase shift masks, and off-axis illumination are being employed to improve the aerial image. In this paper, the impact of the ArF photoresist is investigated. Polymers capable of thermal reflow of larger (~140nm) to smaller (90nm and below) contact holes are presented. Improved materials to achieve the properties necessary for good contact hole imaging for standard single layer resist (SLR) processing are also discussed. State-of-the-art ultra-thin resists (UTR) for contact holes and 193nm bi-layer resist systems are also studied as viable techniques to achieving very small contact holes.

  10. Applications of the 308-nm excimer laser in dermatology

    NASA Astrophysics Data System (ADS)

    Farkas, A.; Kemeny, L.

    2006-05-01

    Excimer lasers contain a mixture of a noble inert gas and a halogen, which form excited dimers only in the activated state. High-energy current is used to produce these dimers, which have a very short lifetime, and after their fast dissociation they release the excitation energy through ultraviolet photons. The application of these lasers proved to be successful in medicine, including the field of ophthalmology, cardiology, angiology, dentistry, orthopaedics, and, in recent years, dermatology. For medical purposes, the 193-nm argon fluoride, the 248-nm krypton fluoride, the 351-nm xenon fluoride, and the 308-nm xenon chloride lasers are used. Recently, the 308-nm xenon chloride laser has gained much attention as a very effective treatment modality in dermatological disorders. It was successfully utilized in psoriasis; later, it proved to be useful in handling other lightsensitive skin disorders and even in the treatment of allergic rhinitis. This review summarizes the possible applications of this promising tool in dermatology.

  11. The preventive effect of linalool on acute and chronic UVB-mediated skin carcinogenesis in Swiss albino mice.

    PubMed

    Gunaseelan, Srithar; Balupillai, Agilan; Govindasamy, Kanimozhi; Muthusamy, Ganesan; Ramasamy, Karthikeyan; Shanmugam, Mohana; Prasad, N Rajendra

    2016-07-01

    In this study, we evaluated the role of linalool in acute ultraviolet-B (UVB; 280-320 nm) radiation-induced inflammation and chronic UVB-mediated photocarcinogenesis in mouse skin. Acute UVB-irradiation (180 mJ cm(-2)) causes hyperplasia, edema formation, lipid peroxidation, antioxidant depletion, and overexpression of cyclooxygenase-2 (COX-2) and ornithine decarboxylase (ODC) in mouse skin. Topical or intraperitoneal (i.p.) treatment of linalool prevented acute UVB-induced hyperplasia, edema formation, lipid peroxidation, and antioxidant depletion in mouse skin. Further, linalool treatment prevented UVB-induced overexpression of COX-2 and ODC in mouse skin. In the chronic study, mice were subjected to UVB-exposure thrice weekly for 30 weeks. Chronic UVB-exposure induced tumor incidence and expression of proliferative markers such as NF-κB, TNF-α, IL-6, COX-2, VEGF, TGF-β1, Bcl-2 and mutated p53 in mouse skin. Treatment with linalool before each UVB-exposure significantly prevented the expression of these proliferative markers and subsequently decreased the tumor incidence in mice skin. Histopathological studies confirmed the development of dysplasia and squamous cell carcinoma (SCC) in the chronic UVB-exposed mouse skin; and this was prevented by both topical and i.p. linalool treatment. Therefore, linalool may be considered as a photochemopreventive agent against UVB radiation induced skin carcinogenesis. PMID:27251985

  12. Icecolors `93: Beginnings of an antarctic phytoplankton and bacterial DNA library from southern ocean natural communities exposed to ultraviolet-B

    SciTech Connect

    Jovine, R.V.M.; Prezelin, B.

    1994-12-31

    Springtime ozone depletion and the resultant increase in ultraviolet-B (UV-B) radiation [280-320 nanometers (nm)] have deleterious effects on primary productivity. To assess damage to cellular components other than the photosynthetic apparatus, we isolated total community DNA from samples in the field before, during, and after the 1993 springtime depletion in stratospheric ozone. The effort was motivated by the concern that the ozone-dependent increases in UV-B radiation may increase DNA damage within primary producers. This increase in damage could result in changes of species composition as well as hereditary changes within species that can influence the competitiveness of these organisms in their natural community. Previous studies have focused on DNA damage in isolated cultures of antarctic phytoplankton that were irradiated with UV-B under lab conditions. These studies clearly indicate variable species sensitivities to the increase in UV-B flux. These studies, however, did not resolve the question of whether such damage occurred in field samples collected from actively mixing, polyphyletic phytoplankton communities. Potential species composition changes and the resultant changes in the trophic dynamics cannot be interpreted in terms of DNA damage unless this damage can be documented in samples isolated under these dynamic natural conditions. 7 refs., 2 figs.

  13. Design of 200-nm, 170-nm, and 140-nm DUV contact sweeper high-transmission attenuating phase-shift mask: II. Experimental results

    NASA Astrophysics Data System (ADS)

    Socha, Robert J.; Shi, Xuelong; Holman, Ken C.; Dusa, Mircea V.; Conley, Will; Petersen, John S.; Chen, J. Fung; Laidig, Thomas L.; Wampler, Kurt E.; Caldwell, Roger F.; Chu, M. C.; Su, Chung Jen; Hung, Kuei-Chun; Chen, C.; Wang, F.; Le, C.; Pierrat, Christophe; Su, Bo

    1999-07-01

    Experiments for 140nm and 160nm contacts were optimized through simulation on an 18 percent transmitting phase shift mask for KrF lithography. A transmission of 18 percent is shown to have the most linear aerial image behavior through focus. The simulations were run using a primitive positive photoresist model in order to predict trends in resolution and to predict when side lobes begin printing. Experiments show that the 140nm and 160nm contact holes resolve without side lobe printing through focus and through exposure. Reticle SEMs verify that a ternary contact hole mask is capable of manufacture. By adding both opaque and clear sub- resolution assist features, the experiments show contacts as small as 140nm resolve with 0.50 micrometers focus latitude with 10 percent exposure latitude through pitch. Cross sectional SEMs verify that contact holes are larger due to the addition of zero order light as suggested by theory and show that side lobes begin to print. Experiments also prove that NA has the largest impact on resolution and exposure latitude and that (sigma) has the largest impact on depth of focus.

  14. Development of a 266 nm Raman lidar for profiling atmospheric water vapor

    NASA Astrophysics Data System (ADS)

    Uesugi, T.; Tsuda, T.; Yabuki, M.; Liu, Y.

    2014-12-01

    It is projected that localized extreme weather events could increase due to the effects of global warming, resulting in severe weather disasters, such as a torrential rain, floods, and so on. Understanding water vapor's behavior in the atmosphere is essen- tial to understand a fundamental mechanism of these weather events. Therefore, continuous monitoring system to measure the atmospheric water vapor with good spatio-temporal resolution is required. We have developed several water vapor Raman lidar systems employing the laser wavelengths of 355 and 532 nm. However, the signal-to-noise ratio of the Raman lidar strongly depends on the sky background because of the detection of the weak inelastic scattering of light by molecules. Therefore, these systems were mainly used during nighttime. Hence, we have newly developed a water vapor Raman lidar using a quadrupled Nd:YAG laser at a wavelength of 266 nm. This wavelength is in the ultraviolet (UV) range below 300 nm known as the "solar-blind" region, because practically all radiation at these wavelengths is absorbed by the ozone layer in the stratosphere. It has the advantage of having no daytime solar background radiation in the system. The lidar is equipped with a 25 cm receiving telescope and is used for measuring the light separated into an elastic backscatter signal and vibrational Raman signals of nitrogen and water vapor at wavelengths of 266.1, 283.6, and 294.6 nm, respectively. This system can be used for continuous water vapor measurements in the lower troposphere. This study introduces the design of the UV lidar system and shows the preliminary results of water vapor profiles.

  15. Lead extraction by selective operation of a nanosecond-pulsed 355nm laser

    NASA Astrophysics Data System (ADS)

    Herzog, Amir; Bogdan, Stefan; Glikson, Michael; Ishaaya, Amiel A.; Love, Charles

    2016-03-01

    Lead extraction (LE) is necessary for patients who are suffering from a related infection, or in opening venous occlusions that prevent the insertion of additional lead. In severe cases of fibrous encapsulation of the lead within a vein, laser-based cardiac LE has become one of the foremost methods of removal. In cases where the laser radiation (typically at 308 nm wavelength) interacts with the vein wall rather than with the fibrotic lesion, severe injury and subsequent bleeding may occur. Selective tissue ablation was previously demonstrated by a laser operating in the UV regime; however, it requires the use of sensitizers (e.g.: tetracycline). In this study, we present a preliminary examination of efficacy and safety aspects in the use of a nanosecond-pulsed solid-state laser radiation, at 355 nm wavelength, guided in a catheter consisting of optical fibers, in LE. Specifically, we demonstrate a correlation between the tissue elasticity and the catheter advancement rate, in ex-vivo experiments. Our results indicate a selectivity property for specific parameters of the laser radiation and catheter design. The selectivity is attributed to differences in the mechanical properties of the fibrotic tissue and a normal vein wall, leading to a different photomechanical response of the tissue's extracellular matrix. Furthermore, we performed successful in-vivo animal trials, providing a basic proof of concept for using the suggested scheme in LE. Selective operation using a 355 nm laser may reduce the risk of blood vessel perforation as well as the incidence of major adverse events.

  16. All-fiber femtosecond Cherenkov radiation source.

    PubMed

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

    2012-07-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580-630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics such as bioimaging and microscopy. PMID:22743523

  17. Wavelength dependence on the forensic analysis of glass by nanosecond 266 nm and 1064 nm laser induced breakdown spectroscopy

    SciTech Connect

    Cahoon, Erica M.; Almirall, Jose R.

    2010-05-01

    Laser induced breakdown spectroscopy can be used for the chemical characterization of glass to provide evidence of an association between a fragment found at a crime scene to a source of glass of known origin. Two different laser irradiances, 266 nm and 1064 nm, were used to conduct qualitative and quantitative analysis of glass standards. Single-pulse and double-pulse configurations and lens-to-sample-distance settings were optimized to yield the best laser-glass coupling. Laser energy and acquisition timing delays were also optimized to result in the highest signal-to-noise ratio corresponding to the highest precision and accuracy. The crater morphology was examined and the mass removed was calculated for both the 266 nm and 1064 nm irradiations. The analytical figures of merit suggest that the 266 nm and 1064 nm wavelengths are capable of good performance for the forensic chemical characterization of glass. The results presented here suggest that the 266 nm laser produces a better laser-glass matrix coupling, resulting in a better stoichiometric representation of the glass sample. The 266 nm irradiance is therefore recommended for the forensic analysis and comparison of glass samples.

  18. 1064 nm laser emission of highly doped Nd: Yttrium aluminum garnet under 885 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Lupei, V.; Pavel, N.; Taira, T.

    2002-06-01

    Highly efficient 1064 nm continuous-wave laser emission under 885 nm diode pumping in concentrated Nd: Yttrium aluminum garnet (YAG) crystals (up to 3.5 at. % Nd) and ceramics (up to 3.8 at. % Nd) is reported. A highly doped (2.4 at. %) Nd:YAG laser, passively Q switched by a Cr4+:YAG saturable absorber, is demonstrated.

  19. Optimization of a gas discharge plasma source for extreme ultraviolet interference lithography at a wavelength of 11 nm

    NASA Astrophysics Data System (ADS)

    Bergmann, K.; Danylyuk, S. V.; Juschkin, L.

    2009-10-01

    In this work, we report about the optimization of the spectral emission characteristic of a gas discharge plasma source for high-resolution extreme ultraviolet (EUV) interference lithography based on achromatic Talbot self-imaging. The working parameters of the source are optimized to achieve a required narrowband emission spectrum and to fulfill the necessary coherence and intensity requirements. The intense 4f-4d transitions around 11 nm in a highly ionized (Xe8+-Xe12+) xenon plasma are chosen to provide the working wavelength. This allows us to increase the available radiation intensity in comparison with an in-band EUV xenon emission at 13.5 nm and opens up the possibility to strongly suppress the influence of the 5p-4d transitions at wavelengths between 12 and 16 nm utilizing a significant difference in conditions for optical thickness between 4f-4d and 5p-4d transitions. The effect is achieved by using the admixture of argon to the pinch plasma, which allows keeping the plasma parameters approximately constant while, at the same time, reducing the density of xenon emitters. It is demonstrated that with this approach it is possible to achieve a high intensity 11 nm EUV radiation with a bandwidth of 3%-4% without the use of multilayer mirrors or other additional spectral filters in the vicinity of the working wavelength. The achieved radiation parameters are sufficient for high-performance interference lithography based on the achromatic Talbot effect.

  20. Time-resolved analysis of catastrophic optical damage in 975 nm emitting diode lasers

    NASA Astrophysics Data System (ADS)

    Hempel, Martin; Ziegler, Mathias; Tomm, Jens W.; Elsaesser, Thomas; Michel, Nicolas; Krakowski, Michel

    2010-06-01

    Catastrophic optical damage (COD) is analyzed during single current pulse excitation of 975 nm emitting diode lasers. Power transients and thermal images are monitored during each pulse. The COD process is unambiguously related to the occurrence of a "thermal flash" of Planck's radiation. We observe COD to ignite multiple times in subsequent pulses. Thermography allows for tracing a spatial motion of the COD site on the front facet of the devices. The time constant of power decay after the onset of COD has values from 400 to 2000 ns, i.e., an order of magnitude longer than observed for shorter-wavelength devices.

  1. Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity

    PubMed Central

    Saeed, A.; Panaro, S.; Zaccaria, R. Proietti; Raja, W.; Liberale, C.; Dipalo, M.; Messina, G. C.; Wang, H.; De Angelis, F.; Toma, A.

    2015-01-01

    The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding. PMID:26057661

  2. Temperature-dependent 780-nm laser absorption by engineering grade aluminum, titanium, and steel alloy surfaces

    SciTech Connect

    Rubenchik, Alexander M.; Wu, Sheldon S. Q.; Kanz, V. Keith; LeBlanc, Mary M.; Lowdermilk, W. Howard; Rotter, Mark D.; Stanley, Joel R.

    2014-07-17

    When modeling laser interaction with metals for various applications it requires a knowledge of absorption coefficients for real, commercially available materials with engineering grade (unpolished, oxidized) surfaces. But, most currently available absorptivity data pertain to pure metals with polished surfaces or vacuum-deposited thin films in controlled atmospheres. A simple laboratory setup is developed for the direct calorimetric absorptivity measurements using a diode-array laser emitting at 780 nm. A scheme eliminating the effect of convective and radiative losses is implemented. Futhermore, the obtained absorptivity results differ considerably from existing data for polished pure metals and are essential for the development of predictive laser-material interaction models.

  3. Evidence for high-efficiency laser-heated hohlraum performance at 527 nm.

    PubMed

    Stevenson, R M; Oades, K; Thomas, B R; Schneider, M; Slark, G E; Suter, L J; Kauffman, R; Hinkel, D; Miller, M C

    2005-02-11

    A series of experiments conducted on the HELEN laser system [M. J. Norman, Appl. Opt.4120023497], into thermal x-ray generation from hohlraum targets using 527 nm (2omega) wavelength laser light, has shown that it is possible to exceed radiation temperatures previously thought limited by high levels of superthermal or hot electron production or stimulated backscatter. This Letter questions whether the assumptions traditionally applied to hohlraum design with respect to hot plasma filling and the use of 2omega light are too conservative. PMID:15783658

  4. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  5. Modeling the distributed gain of single--(1050 or 1410 nm) and dual-wavelength--(800 + 1050 nm or 800 + 1410 nm) pumped thulium-doped fiber amplifiers.

    PubMed

    Floridia, Claudio; Carvalho, M T; Lüthi, S R; Gomes, A S L

    2004-09-01

    The distributed gain of single- and dual-wavelength-pumped thulium-doped fiber amplifiers is modeled. The excellent agreement between the model and coherent optical frequency domain reflectometry measurements enables us to estimate intrinsic loss, branching ratios of fluorescence originating from the 3H4 level, and cross sections of upconversion pumping at 1050 and 1410 nm for the Tm3+ ions in the fiber. With the branching ratios obtained it is possible to describe induced signal absorption when pumping at 800 nm. PMID:15455754

  6. Phase-matched frequency conversion below 150 nm in KBe2BO3F2.

    PubMed

    Nakazato, Tomoharu; Ito, Isao; Kobayashi, Yohei; Wang, Xiaoyang; Chen, Chuangtian; Watanabe, Shuntaro

    2016-07-25

    Sum frequency mixing has been demonstrated below 150 nm in KBeBO3F2 by using the fundamental with its fourth harmonic of a 6 kHz Ti: sapphire laser system. The wavelength of 149.8 nm is the shortest ever obtained to our knowledge by phase matching in nonlinear crystals. The output powers were 3.6 μW at 149.8 nm and 110 μW at 154.0 nm, respectively. The phase matching angles measured from 149.8 to 158.1 nm are larger by 3-4 degrees than those expected from the existing Sellmeier equation. The measured transmission spectra of KBeBO3F2 crystals support the generation of coherent radiation below 150 nm. PMID:27464165

  7. Study of 193-nm resist degradation under various etch chemistries

    NASA Astrophysics Data System (ADS)

    Bazin, Arnaud; May, Michael; Pargon, Erwine; Mortini, Benedicte; Joubert, Olivier

    2007-03-01

    The effectivity of 193nm photoresists as dry etch masks is becoming more and more critical as the size of integrated devices shrinks. 193nm resists are known to be much less resistant to dry etching than 248nm resists based on a poly(hydroxystyrene) polymer backbone. The decrease in the resist film budget implies a better etch resistance to use single layer 193nm photoresists for the 65nm node and beyond. In spite of significant improvements made in the past decade regarding the etch resistance of photoresists, much of the fundamental chemistry and physics that could explain the behaviour of these materials has to be better understood. Such knowledge is necessary in order to propose materials and etch processes for the next technology nodes (45nm and below). In this paper, we report our studies on the etch behaviour of different 193nm resist materials as a function of etch chemistry. In a first step, we focus our attention on the interactions between photoresists and the reactive species of a plasma during a dry etch step. Etch experiments were carried out in a DPS (Decoupled Plasma Source) high density chamber. The gas chemistry in particular was changed to check the role of the plasma reactive species on the resist. O II, Cl II, CF 4, HBr and Ar gas were used. Etch rates and chemical modifications of different materials were quantified by ellipsometry, Fourier Transformed Infrared Spectroscopy (FTIR), and X-Ray Photoelectrons Spectroscopy (XPS). We evaluated different materials including 248nm model polymer backbones (pure PHS or functionalized PHS), and 193nm model polymers (PMMA and acrylate polymers) or resist formulations. Besides the influence of resist chemistry, the impact of plasma parameters was addressed.

  8. Characterization of focused beam of desktop 10-Hz capillary-discharge 46.9-nm laser

    NASA Astrophysics Data System (ADS)

    Vyšin, Ludek; Burian, Tomás; Chalupský, Jaromír; Grisham, Michael; Hájková, Vera; Heinbuch, Scott; Jakubczak, Krzysztof; Martz, Dale; Mocek, Tomás; Pira, Peter; Polan, Jirí; Rocca, Jorge J.; Rus, Bedrich; Sobota, Jaroslav; Juha, Libor

    2009-05-01

    The desktop capillary-discharge Ne-like Ar laser (CDL) providing 10-μJ nanosecond pulses of coherent 46.9-nm radiation with a repetition rate up to 12 Hz was developed and built at the Colorado State University in Fort Collins and then installed in Prague. The beam of the laser was focused by a spherical mirror covered with Si/Sc multilayer coating onto the surface of poly(methyl methacrylate) - PMMA. Interaction parameters vary by changing the distance between sample surface and beam focus. The samples were exposed to various numbers of shots. Analysis of damaged PMMA by atomic force (AFM) and Nomarski (DIC - differential interference contrast) microscopes allows not only to determine the key characteristics of the focused beam (e.g. Rayleigh's parameter, focal spot diameter, tight focus position, etc.) but also to investigate mechanisms of the radiation-induced erosion processes.

  9. 1-Grad total dose evaluation of 65 nm CMOS technology for the HL-LHC upgrades

    NASA Astrophysics Data System (ADS)

    Menouni, M.; Barbero, M.; Bompard, F.; Bonacini, S.; Fougeron, D.; Gaglione, R.; Rozanov, A.; Valerio, P.; Wang, A.

    2015-05-01

    The radiation tolerance of 65 nm bulk CMOS devices was investigated using 10 keV X-rays up to a Total Ionizing Dose (TID) of 1 Grad. Irradiation tests were performed at room temperature (25°C) as well as at low temperature (-15°C). The implications on the DC performance of n and p channel transistors are presented. For small size devices, a strong performance degradation is observed from a dose of 100 Mrad. Irradiations made at room temperature up to 1 Grad show a complete drive loss in PMOS devices, due to decreasing transconductance. When the irradiation is conducted at -15°C, the devices show less radiation damage. Annealing helps recovering a small part of the drive capabilities of the small size devices, but the threshold voltage shift is still high and might compromise the operation in some digital applications.

  10. Shot noise startup of the 6 NM SASE FEL at the Tesla Test Facility

    SciTech Connect

    Pierini, P.; Fawley, W.M.

    1995-12-31

    We present here an analysis of the shot noise startup of the 6 nm SASE FEI proposal at the TESLA Test Facility in DESY The statistical of the saturation length and output power due to the intrinsic randomness of the noise startup are investigated with the use of the 2D time dependent code GINGER, that takes into account propagation effects and models shot noise. We then provide estimates for the spectral contents and linewidth of the emitted radiation and describe its spiking characteristics. The output radiation will develop superradiant spikes seeded by the shot noise in the electron beam, which can entrance the average emitted power at the expense of some spectral broadening.

  11. Sub-100 nm patterning of supported bilayers by nanoshaving lithography.

    PubMed

    Shi, Jinjun; Chen, Jixin; Cremer, Paul S

    2008-03-01

    Sub-100 nm wide supported phospholipid bilayers (SLBs) were patterned on a planar borosilicate substrate by AFM-based nanoshaving lithography. First, a bovine serum albumin monolayer was coated on the glass and then selectively removed in long strips by an AFM tip. The width of vacant strips could be controlled down to 15 nm. Bilayer lines could be formed within the vacant strips by vesicle fusion. It was found that stable bilayers formed by this method had a lower size limit of approximately 55 nm in width. This size limit stems from a balance between a favorable bilayer adhesion energy and an unfavorable bilayer edge energy. PMID:18257567

  12. 80 nm tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.

    2016-07-01

    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  13. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S; Kurkov, A S

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  14. Histological study of the thyroid gland following 904-nm laser radiation

    NASA Astrophysics Data System (ADS)

    Perez de Vargas, I.; Parrado, C.; Gonzalez, V.; Vidal, Lourdes; Rius, F.

    1993-06-01

    The present histological and stereological studies are on thyroid glands of Wistar rats irradiated with an IR laser. The animals were exposed to total doses of 46,80 J/cm2, and sacrificed at 1, 40, and 180 days after the last treatment. A morphological and stereological study was made on follicular epithelium, follicle, stroma, and capillary. The laser beam produced an increase of follicular epithelial volume and hyperplasia of follicular cells in the animals sacrificed at 1, 40, and 180 days after the last treatment. Capillary dilation underwent a progressive decrease as time passed. It was higher in the animals sacrificed after 24 hours, then it decreased after 40 days and finally disappeared after 180 days.

  15. Evaluation of a 345 nm Femtosecond Laser for Corneal Surgery with Respect to Intraocular Radiation Hazard

    PubMed Central

    Tourtas, Theofilos; Polisetti, Naresh; Klenke, Jörg; Skerl, Katrin; Wüllner, Christian; Donitzky, Christof; Kruse, Friedrich E.; Kremers, Jan; Hammer, Christian M.

    2015-01-01

    Purpose We report our findings from a preclinical safety study designed to assess potential side effects of corneal ultraviolet femtosecond laser treatment on lens and retina. Methods Refractive lenticules (-5 dpt) with a diameter of 6 mm were created in the right cornea of eight Dutch Belted rabbits. Radiant exposure was 0.5 J/cm² in two animals and 18 J/cm² in six animals. The presence of lens opacities was assessed prior to and up to six months following laser application using Scheimpflug images (Pentacam, Oculus) and backscatter analysis (Opacity Lensmeter 702, Interzeag). Ganzfeld flash and flicker electroretinogram (ERG) recordings were obtained from both eyes prior to and up to six weeks following laser application. At the study endpoint, retinas were examined by light microscopy. Results Independent of energy dose applied, no cataract formation could be observed clinically or with either of the two objective methods used. No changes in ERG recordings over time and no difference between treated and untreated eye were detected. Histologically, retinal morphology was preserved and retinal pigment epithelium as well as photoreceptor inner and outer segments appeared undamaged. Quantitative digital image analysis did not reveal cell loss in inner or outer nuclear layers. Conclusions Our analysis confirms theoretical considerations suggesting that ultraviolet femtosecond laser treatment of the cornea is safe for intraocular tissues. Transmitted light including stray light induces no photochemical effects in lens or retina at energy levels much higher than required for the clinical purpose. These conclusions cannot be applied to eyes with pre-existing retinal damage, as these may be more vulnerable to light. PMID:26361228

  16. Imaging spectrometer measurement of water vapor in the 400 to 2500 nm spectral region

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Roberts, Dar A.; Conel, James E.; Dozier, Jeff

    1995-01-01

    The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) measures the total upwelling spectral radiance from 400 to 2500 nm sampled at 10 nm intervals. The instrument acquires spectral data at an altitude of 20 km above sea level, as images of 11 by up to 100 km at 17x17 meter spatial sampling. We have developed a nonlinear spectral fitting algorithm coupled with a radiative transfer code to derive the total path water vapor from the spectrum, measured for each spatial element in an AVIRIS image. The algorithm compensates for variation in the surface spectral reflectance and atmospheric aerosols. It uses water vapor absorption bands centered at 940 nm, 1040 nm, and 1380 nm. We analyze data sets with water vapor abundances ranging from 1 to 40 perceptible millimeters. In one data set, the total path water vapor varies from 7 to 21 mm over a distance of less than 10 km. We have analyzed a time series of five images acquired at 12 minute intervals; these show spatially heterogeneous changes of advocated water vapor of 25 percent over 1 hour. The algorithm determines water vapor for images with a range of ground covers, including bare rock and soil, sparse to dense vegetation, snow and ice, open water, and clouds. The precision of the water vapor determination approaches one percent. However, the precision is sensitive to the absolute abundance and the absorption strength of the atmospheric water vapor band analyzed. We have evaluated the accuracy of the algorithm by comparing several surface-based determinations of water vapor at the time of the AVIRIS data acquisition. The agreement between the AVIRIS measured water vapor and the in situ surface radiometer and surface interferometer measured water vapor is 5 to 10 percent.

  17. Etching of fused silica and glass with excimer laser at 351 nm

    NASA Astrophysics Data System (ADS)

    Zimmer, K.; Braun, A.; Böhme, R.

    2003-03-01

    The etching of solid surfaces at the interface to liquids is a new promising method for micro-machining of transparent materials. To extend the method to additional materials the pulsed radiation of a XeF-excimer laser (351 nm) was used for etching different types of glass (Corning Inc.: Pyrex, 7059 and Schott Group: D263, AF45) and fused silica for comparison. The etch rates of the investigated materials increase almost linear at low laser fluences. Threshold fluences for glass as low as 0.5 J/cm 2 and etch rates from 6 to 10 nm per pulse at 1 J/cm 2 have been determined. The etch rate and the threshold fluence depend also on the used liquid, consisting of a solvent (acetone, toluene) and a certain concentration of dissolved pyrene, but only little on the glass type. Due to the low etch rate typically very smooth surfaces are achieved. The surface roughness measured by AFM on Corning 7059-glass at an etch depth of 3.7 μm is as low as 4 nm. Contrary to the other glasses the surface roughness of Pyrex is much higher and dominated by typical arbitrary etch pits with micron dimensions. Comparing the etching of fused silica at a wavelength of 248 and 351 nm the used solution influences both the etch threshold and the etch rate. In accordance to earlier investigations at 248 nm also XeF-laser etching at the interface to an absorbing liquid results in a good surface quality, well defined patterns and almost no debris deposition. Thus, this technique is a good candidate for precise micro-machining applications.

  18. Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

    SciTech Connect

    Tong, A.K.; Tan, O.T.; Boll, J.; Parrish, J.A.; Murphy, G.F.

    1987-06-01

    It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.

  19. Space Radiation

    NASA Technical Reports Server (NTRS)

    Wu, Honglu

    2006-01-01

    Astronauts receive the highest occupational radiation exposure. Effective protections are needed to ensure the safety of astronauts on long duration space missions. Increased cancer morbidity or mortality risk in astronauts may be caused by occupational radiation exposure. Acute and late radiation damage to the central nervous system (CNS) may lead to changes in motor function and behavior, or neurological disorders. Radiation exposure may result in degenerative tissue diseases (non-cancer or non-CNS) such as cardiac, circulatory, or digestive diseases, as well as cataracts. Acute radiation syndromes may occur due to occupational radiation exposure.

  20. Method of Express Analysis of Temporal Evolution of the Spectral and Angular Distributions of Seps during Gles Using NM Data

    NASA Astrophysics Data System (ADS)

    Mishev, Alexander; Usoskin, Ilya

    It is important for space weather studies to be estimate radiation environment during major SEP (solar energetic particle) events. For this purpose, the main characteristics, viz. spectra and anisotropy of SEPs, should be derived in near real time. Here we present a method for a quasi-real time analysis of ground level enhancements using neutron monitor (NM) data. The method is based on a precise computations of SEP propagation in the Earth's magnetosphere, namely the assymptotic cones of acceptance of NM, application of the new computed neutron monitor yield function and non-linear optimization. Several examples and a comparison with previously obtained results as well with full scale modeling are demonstrated.

  1. Measurement of the Electron Impact Photoemission Cross Sections of the 92.0 NM and 93.2 NM Emission Lines of Argon II for the VUV Radiometric Project.

    NASA Astrophysics Data System (ADS)

    McPherson, Leroy Armon, Jr.

    Measurements of the electron impact photoemission cross sections for 92.0 nm and 93.2 nm radiation from Ar II have been made. The unpolarized radiation is produced by transitions from the 3s3p('6) ('2)S(,1/2) state to the 3s('2)3p('5) ('2)P(,1/2'3/2) states. The cross sections were determined at an incident electron energy of 100 eV and found to be (5.81 (+OR-) 0.48) x 10('-18) cm('2) for the 92.0 nm line (S(,1/2)(--->)P(,3/2)) and (3.00 (+OR -) 0.25) x 10('-18) cm('2) for the 93.2 nm line (S(,1/2)( --->)P(,1/2)). The Ar II photoemission cross sections will be part of an atlas of electron impact photoemission cross sections for emission lines throughout the vuv wavelength region. This atlas will form the basis of a new portable primary vuv radiometric standard. The new intensity standard consists of an electron beam used to excite gas atoms which subsequently emit characteristic line radiation. The absolute photon flux emitted in an emission line can be determined if the electron impact photoemission cross section for the emission line is known, along with the target gas density and the electron beam current. The absolute radiometric standard can be used to determine the detection efficiency of any uncalibrated spectrometer-detector system. The cross section measurements were made using a spectrometer with an optical system similar to the Seya -Namioka design. A type IV holographic grating with an aluminum surface overcoated with MgF(,2) was used. The detector was a venetian blind photomultiplier with a BeCu cathode. The detection efficiency was determined by using well parameterized synchrotron radiation from SURF-II at the National Bureau of Standards in Gaithersburg, Maryland. A large multiadjustable manipulator positioned the spectrometer to view a beam of synchrotron radiation as if it originated from points along the electron beam. The spectrometer -detector system response was determined separately for incident synchrotron radiation polarized both parallel

  2. Radiation in controlled environments: influence of lamp type and filter material

    NASA Technical Reports Server (NTRS)

    Bubenheim, D. L.; Bugbee, B.; Salisbury, F. B.

    1988-01-01

    Radiation in controlled environments was characterized using fluorescent and various high-intensity-discharge (HID) lamps, including metal halide, low-pressure sodium, and high-pressure sodium as the radiation source. The effects of water, glass, or Plexiglas filters on radiation were determined. Photosynthetic photon flux (PPF, 400 to 700 nm), spectra (400 to 1000 nm), shortwave radiation (285-2800 nm), and total radiation (300 to 100,000 nm) were measured, and photosynthetically active radiation (PAR, 400 to 700 nm) and longwave radiation (2800 to 100,000 nm) were calculated. Measurement of PPF alone was not an adequate characterization of the radiation environment. Total radiant flux varied among lamp types at equal PPF. HID lamps provided a lower percentage of longwave radiation than fluorescent lamps, but, when HID lamps provided PPF levels greater than that possible with fluorescent lamps, the amount of longwave radiation was high. Water was the most effective longwave radiation filter. Glass and Plexiglas similarly filtered longwave more than shortwave radiation, but transmission of nonphotosynthetic shortwave radiation was less with Plexiglas than glass. The filter materials tested would not be expected to influence photomorphogenesis because radiation in the action spectrum of phytochrome was not altered, but this may not be the only pigment involved.

  3. Metastasis suppressors Nm23H1 and Nm23H2 differentially regulate neoplastic transformation and tumorigenesis.

    PubMed

    Tong, Yao; Yung, Lisa Y; Wong, Yung H

    2015-06-01

    Nm23H1 and H2 are prototypical metastasis suppressors with diverse functions, but recent studies suggest that they may also regulate tumorigenesis. Here, we employed both cellular and in vivo assays to examine the effect of Nm23H1 and H2 on tumorigenesis induced by oncogenic Ras and/or p53 deficiency. Co-expression of Nm23H1 but not H2 in NIH3T3 cells effectively suppressed neoplastic transformation and tumorigenesis induced by the oncogenic H-Ras G12V mutant. Overexpression of Nm23H1 but not H2 also inhibited tumorigenesis by human cervical cancer HeLa cells with p53 deficiency. However, in human non-small-cell lung carcinoma H1299 cells harboring N-Ras Q61K oncogenic mutation and p53 deletion, overexpression of Nm23H1 did not affect tumorigenesis in nude mice assays, while overexpression of Nm23H2 enhanced tumor growth with elevated expression of the c-Myc proto-oncogene. Collectively, these results suggest that Nm23H1 and H2 have differential abilities to modulate tumorigenesis. PMID:25748386

  4. Efficient laser operation of Nd3+:Lu2O3 at various wavelengths between 917 nm and 1463 nm

    NASA Astrophysics Data System (ADS)

    von Brunn, P.; Heuer, A. M.; Fornasiero, L.; Huber, G.; Kränkel, C.

    2016-08-01

    Even though the first Nd3+-doped sesquioxide lasers have been realized more than 50 years ago, up to now no reports on efficient laser operation of Nd3+:doped sesquioxides can be found. In this work, we review the favorable spectroscopic properties of the sesquioxide Nd3+:Lu2O3 in terms of ground state absorption, stimulated emission, and excited state absorption cross sections as well as the upper level lifetime. Making use of these properties, we achieved efficient laser performance on eight different laser transitions in the wavelength range between 917 nm and 1463 nm under Ti:sapphire laser pumping using state-of-the-art HEM-grown Nd3+:Lu2O3 crystals with good optical quality. At the strongest transition around 1076 nm we determined a slope efficiency of 69%, which represents the highest efficiency ever obtained for a Nd3+-doped sesquioxide. Furthermore, we could generate watt level output powers and high slope efficiencies for seven other transitions. Lasers at 917 nm, 1053 nm, 1108 nm and 1463 nm were realized for the first time and the latter represents one of the longest laser wavelengths obtained on the 4F3/2  →  4I13/2 transition in Nd3+-doped materials.

  5. High-resolution optical signatures of fresh and aged explosives in the 420nm to 620nm illumination range

    NASA Astrophysics Data System (ADS)

    Lunsford, Robert; Grun, Jacob; Gump, Jared

    2012-06-01

    Optical signatures of fresh and aged explosives are measured and compared to determine whether there exist differences in the signatures that can be exploited for detection. The explosives examined are RDX, TNT, and HMX, which have been heated for two weeks at 75 degrees centigrade or irradiated for two weeks with a 15-Watt ultraviolet lamp (254nm). The optical signatures are obtained by illuminating the samples with a sequence of laser wavelengths between 420nm and 620nm in 10 nm steps and measuring the spectra of light scattered from the sample at each laser wavelength. The measurements are performed on the Naval Research Laboratory's SWOrRD instrument. SWOrRD is capable of illuminating a sample with laser wavelength between 210nm and 2000nm, in steps of 0.1nm, and measuring the spectrum of light scattered from the sample at each wavelength. SWOrRD's broad tuning range, high average power (1- 300mW), narrow line width (< 4cm-1), and rapid wavelength tunability enable these measurements. Results, based on more than 80 measurements - each at 21 sequential laser wavelengths, indicate that the variation in spectral line amplitude observed when altering laser illumination wavelength differs between fresh and aged explosives. Thus, an instrument for rapid and reagent-less differentiation between aged and fresh explosives, based on illumination with a few appropriately chosen laser wavelengths appears feasible.

  6. Compact frequency-quadrupled pulsed 1030nm fiber laser

    NASA Astrophysics Data System (ADS)

    McIntosh, Chris; Goldberg, Lew; Cole, Brian; DiLazaro, Tom; Hays, Alan D.

    2016-03-01

    A compact 1030nm fiber laser for ultraviolet generation at 257.5nm is presented. The laser employs a short length of highly-doped, large core (20μm), coiled polarization-maintaining ytterbium-doped double-clad fiber pumped by a wavelength-stabilized 975nm diode. It is passively Q-switched via a Cr4+:YAG saturable absorber and generates 2.4W at 1030nm in a 110μJ pulse train. Lithium triborate (LBO) and beta-barium borate (BBO) are used to achieve 325mW average power at the fourth harmonic. The laser's small form factor, narrow linewidth and modest power consumption are suitable for use in a man-portable ultraviolet Raman explosives detection system.

  7. Fiber-integrated 780 nm source for visible parametric generation.

    PubMed

    Hu, D J J; Murray, R T; Legg, T; Runcorn, T H; Zhang, M; Woodward, R I; Lim, J L; Wang, Y; Luan, F; Gu, B; Shum, P P; Kelleher, E J R; Popov, S V; Taylor, J R

    2014-12-01

    We report the development of a fully fiber-integrated pulsed master oscillator power fibre amplifier (MOPFA) source at 780 nm, producing 3.5 W of average power with 410 ps pulses at a repetition rate of 50 MHz. The source consists of an intensity modulated 1560 nm laser diode amplified in an erbium fiber amplifier chain, followed by a fiber coupled periodically poled lithium niobate crystal module for frequency doubling. The source is then used for generating visible light through four-wave mixing in a length of highly nonlinear photonic crystal fiber: 105 mW at 668 nm and 95 mW at 662 nm are obtained, with pump to anti-Stokes conversion slope efficiencies exceeding 6% in both cases. PMID:25606903

  8. Photorefractive effect at 775 nm in doped lithium niobate crystals

    SciTech Connect

    Nava, G.; Minzioni, P.; Cristiani, I.; Degiorgio, V.; Argiolas, N.; Bazzan, M.; Ciampolillo, M. V.; Pozza, G.; Sada, C.

    2013-07-15

    The photorefractive effect induced by 775-nm laser light on doped lithium niobate crystals is investigated by the direct observation in the far field of the transmitted-beam distortion as a function of time. Measurements performed at various Zr-doping concentrations and different light intensities show that the 775-nm light beam induces a steady-state photorefractive effect comparable to that of 532-nm light, but the observed build-up time of the photovoltaic field is longer by three-orders of magnitude. The 775-nm photorefractivity of lithium niobate crystals doped with 3 mol. % ZrO{sub 2} or with 5.5 mol. % MgO is found to be negligible.

  9. 100-nm node lithography with KrF?

    NASA Astrophysics Data System (ADS)

    Fritze, Michael; Tyrrell, Brian; Astolfi, David K.; Yost, Donna; Davis, Paul; Wheeler, Bruce; Mallen, Renee D.; Jarmolowicz, J.; Cann, Susan G.; Liu, Hua-Yu; Ma, M.; Chan, David Y.; Rhyins, Peter D.; Carney, Chris; Ferri, John E.; Blachowicz, B. A.

    2001-09-01

    We present results looking into the feasibility of 100-nm Node imaging using KrF, 248-nm, exposure technology. This possibility is not currently envisioned by the 1999 ITRS Roadmap which lists 5 possible options for this 2005 Node, not including KrF. We show that double-exposure strong phase- shift, combined with two mask OPC, is capable of correcting the significant proximity effects present for 100-nm Node imaging at these low k1 factors. We also introduce a new PSM Paradigm, dubbed 'GRATEFUL,' that can image aggressive 100-nm Node features without using OPC. This is achieved by utilizing an optimized 'dense-only' imaging approach. The method also allows the re-use of a single PSM for multiple levels and designs, thus addressing the mask cost and turnaround time issues of concern in PSM technology.

  10. Absolute measurement of F2-laser power at 157 nm

    SciTech Connect

    Kueck, Stefan; Brandt, Friedhelm; Kremling, Hans-Albert; Gottwald, Alexander; Hoehl, Arne; Richter, Mathias

    2006-05-10

    We report a comparison of laser power measurements at the F2-laser wavelength oaf nm made at two facilities of the Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute. At the PTB laboratory at the electron storage ring BESSY II in Berlin, the scale for laser power was directly traced to a cryogenic radiometer operating at 157 nm, whereas at the PTB laser radiometry facility in Braunschweig the calibration of transfer detectors was performed with a newly developed standard for laser power at 157 nm, which is traceable in several steps to a cryogenic radiometer operating at 633 nm. The comparison was performed under vacuum conditions with laser pulse energies of?10 {mu}J, however with different average powers because different primary standard radiometers were used. The relative deviation for the responsivity of the transfer detector was 4.8% and thus within the combined standard uncertainty.

  11. 980 nm narrow linewidth Yb-doped phosphate fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Yao, Yifei; Hu, Haowei; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Zhang, Guangju

    2014-12-01

    A narrow-linewidth ytterbium (Yb)-doped phosphate fiber laser based on fiber Bragg grating (FBG) operating around 980 nm is reported. Two different kinds of cavity are applied to obtain the 980 nm narrow-linewidth output. One kind of the cavity consists of a 0.35 nm broadband lindwidth high-reflection FBG and the Yb-doped phosphate fiber end with 0° angle, which generates a maximum output power of 25 mW. The other kind of resonator is composed of a single mode Yb-doped phosphate fiber and a pair of FBGs. Over 10.7 mW stable continuous wave are obtained with two longitudinal modes at 980 nm. We have given a detailed analysis and discussion for the results.

  12. Raman spectroscopy using 1550 nm (retina-safe) laser excitation.

    PubMed

    Brouillette, Carl; Huang, Hermes; Smith, Wayne; Farquharson, Stuart

    2011-05-01

    During the past decade, the use of portable Raman analyzers for field measurements has grown dramatically. However, most analyzers use 785 nm excitation lasers that can cause permanent eye damage. To overcome this safety concern, we have built a portable Fourier transform (FT) Raman analyzer using a 1550 nm retina-safe excitation laser and have compared its performance to our 1064 nm FT-Raman analyzer, which uses the same optical design. Raman theory predicts approximately five times lower peak intensities at 1550 nm. Although we found that intensities were as much as 20 times less intense, the analyzer is still capable of measuring spectra of sufficient quality to identify and differentiate chemicals. PMID:21513601

  13. The inactivation of eggs of helminthes under the action of narrowband ultraviolet radiation of excilamps

    NASA Astrophysics Data System (ADS)

    Lipatov, Evgeniy I.; Sosnin, Edward A.; Avdeev, Sergey M.

    2015-12-01

    The inactivation of eggs of Opisthorchis felineus and Diphyllobothrium latum in the water under the action of UV excilamps at 222 and 282 nm in dependence on the surface dose of radiation was studied. It was observed that the water disinfection from eggs of helminthes was more efficient at 222 nm, than at 282 nm. At the surface dose up to 5 mJ/cm2 of UV radiation at 222 nm up to 85 % of Opisthorchis felineus eggs were inactivated. At the comparable surface dose of UV radiation at 222 nm up to 56 % of Diphyllobothrium latum eggs were inactivated.

  14. The Missing Solar Irradiance Spectrum: 1 to 7 nm

    NASA Astrophysics Data System (ADS)

    Sojka, J. J.; Lewis, M.; David, M.; Schunk, R. W.; Woods, T. N.; Eparvier, F. G.; Warren, H. P.

    2015-12-01

    During large X-class flares the Earth's upper atmospheric E-region responds immediately to solar photons in the 1 to 7 nm range. The response can change the E-region density by factors approaching 10, create large changes in conductivity, and plague HF communications. GOES-XRS provide 0.1 to 0.8 nm and a 0.05 to 0.4 nm integral channels; SOHO-SEM provided a 0 to 50 nm irradiance; TIMED and SORCE-XPS diode measurements also integrated down to 0.1 nm; and most recently SDO-EVE provided a 0.1 to 7 nm irradiance. For atmospheric response to solar flares the cadence is also crucial. Both GOES and SDO provided integral measurements at 10 seconds or better. Unfortunately these measurements have failed to capture the 1 to 7 nm spectral changes that occur during flares. It is these spectral changes that create the major impact since the ionization cross-section of the dominant atmospheric species, N2 and O2, both contain step function changes in the cross-sections. Models of the solar irradiance over this critical wavelength regime have suffered from the need to model the spectral variability based on incomplete measurements. The most sophisticated empirical model FISM [Chamberlin et al., 2008] used 1 nm spectral binning and various implementations of the above integral measurements to describe the 1 to 7 nm irradiance. Since excellent solar observations exist at other wavelengths it is possible to construct an empirical model of the solar atmosphere and then use this model to infer the spectral distribution at wavelengths below 5 nm. This differential emission measure approach has been used successfully in other contexts [e.g., Warren, 2005, Chamberlin et al., 2009]. This paper contrasts the broadband versus spectrally resolved descriptions of the incoming irradiance that affects the upper atmospheric E-layer. The results provide a prescription of what wavelength resolution would be needed to adequately measure the incoming solar irradiance in the 1 to 7 nm range.

  15. Low-k/copper integration scheme suitable for ULSI manufacturing from 90nm to 45nm nodes

    NASA Astrophysics Data System (ADS)

    Nogami, T.; Lane, S.; Fukasawa, M.; Ida, K.; Angyal, M.; Chanda, K.; Chen, F.; Christiansen, C.; Cohen, S.; Cullinan, M.; Dziobkowski, C.; Fitzsimmons, J.; Flaitz, P.; Grill, A.; Gill, J.; Inoue, K.; Klymko, N.; Kumar, K.; Labelle, C.; Lane, M.; Li, B.; Liniger, E.; Madon, A.; Malone, K.; Martin, J.; McGahay, V.; McLaughlin, P.; Melville, I.; Minami, M.; Molis, S.; Nguyen, S.; Penny, C.; Restaino, D.; Sakamoto, A.; Sankar, M.; Sherwood, M.; Simonyi, E.; Shimooka, Y.; Tai, L.; Widodo, J.; Wildman, H.; Ono, M.; McHerron, D.; Nye, H.; Davis, C.; Sankaran, S.; Edelstein, D.; Ivers, T.

    2005-11-01

    This paper discusses low-k/copper integration schemes which has been in production in the 90 nm node, have been developed in the 65 nm node, and should be taken in the 45 nm node. While our baseline 65 nm BEOL process has been developed by extension and simple shrinkage of our PECVD SiCOH integration which has been in production in the 90 nm node with our SiCOH film having k=3.0, the 65 nm SiCOH integration has two other options to go to extend to lower capacitance. One is to add porosity to become ultra low-k (ULK). The other is to stay with low-k SiCOH, which is modified to have a "lower-k". The effective k- value attained with the lower-k (k=2.8) SiCOH processed in the "Direct CMP" scheme is very close to that with an ULK (k=2.5) SiCOH film built with the "Hard Mask Retention" scheme. This paper first describes consideration of these two damascene schemes, whose comparison leads to the conclusion that the lower-k SiCOH integration can have more advantages in terms of process simplicity and extendibility of our 90 nm scheme under certain assumptions. Then describing the k=2.8 SiCOH film development and its successful integration, damascene schemes for 45nm nodes are discussed based on our learning from development of the lower-k 65nm scheme. Capability of modern dry etchers to define the finer patterns, non-uniformity of CMP, and susceptibility to plasma and mechanical strength and adhesion of ULK are discussed as factors to hamper the applicability of ULK.

  16. Evolution of the gate current in 32 nm MOSFETs under irradiation

    NASA Astrophysics Data System (ADS)

    Palumbo, F.; Debray, M.; Vega, N.; Quinteros, C.; Kalstein, A.; Guarin, F.

    2016-05-01

    Radiation induced currents on single 32 nm MOSFET transistors have been studied using consecutive runs of 16O at 25 MeV. The main feature is the generation of current peaks - in the gate and channel currents - due to the collection of the electro-hole pairs generated by the incident radiation runs. It has been observed that the incident ions cause damage in the dielectric layer and in the substrate affecting the collection of carriers, and hence the radiation-induced current peaks. It has been find out a decrease of the current peak due to the increase of the series resistance by non-ionizing energy loss in the semiconductor substrate, and an increase of the leakage current due to defects in the gate oxide by ionizing energy loss. For low levels of damage in the gate oxide, the main feature is the shift of the VTH. Hot carriers heated by the incident radiation in the depletion region and injected in the gate oxide cause the change of the VTH due to electron or hole trapping for n- or p-channel respectively. The overall results illustrate that these effects must be taken into consideration for an accurate reliability projection.

  17. Applications of combination wavelength (1060-nm and 530-nm) and pulsed Nd:YAG laser for contact laser surgery.

    PubMed

    Liu, K R; Peyman, G A; Myers, J D; Hamlin, S A; Katoh, N

    1989-01-01

    Two pulsed neodimium yittrium aluminum garnet (Nd:YAG) laser systems were evaluated for contact surgery through a fiberoptic system with a sapphire tip. Pulsed Nd:YAG laser at 1060 nm was as effective as continuous-wave Nd:YAG laser in producing tissue incisions. A combination of 1060-nm and 530-nm wavelengths achieved smooth cutting at lower energy levels. Corneal endothelial cell damage occurred at the high power level (7 watts) required for smooth underwater incisions with both continuous wave and pulsed lasers. PMID:2733255

  18. Trends in nanosecond melanosome microcavitation up to 1540 nm

    NASA Astrophysics Data System (ADS)

    Schmidt, Morgan S.; Kennedy, Paul K.; Noojin, Gary D.; Vincelette, Rebecca L.; Thomas, Robert J.; Rockwell, Benjamin A.

    2015-09-01

    Thresholds for microcavitation of bovine and porcine melanosomes were previously reported, using single nanosecond (ns) laser pulses in the visible (532 nm) and the near-infrared (NIR) from 1000 to 1319 nm. Here, we report average radiant exposure thresholds for bovine melanosome microcavitation at additional NIR wavelengths up to 1540 nm, which range from ˜0.159 J/cm2 at 800 nm to 4.5 J/cm2 at 1540 nm. Melanosome absorption coefficients were also estimated, and decreased with increasing wavelength. These values were compared to retinal pigment epithelium coefficients, and to water absorption, over the same wavelength range. Corneal total intraocular energy retinal damage threshold values were estimated and compared to the previous (2007) and recently changed (2014) maximum permissible exposure (MPE) safe levels. Results provide additional data that support the recent changes to the MPE levels, as well as the first microcavitation data at 1540 nm, a wavelength for which melanosome microcavitation may be an ns-pulse skin damage mechanism.

  19. Alternatives to chemical amplification for 193nm lithography

    NASA Astrophysics Data System (ADS)

    Baylav, Burak; Zhao, Meng; Yin, Ran; Xie, Peng; Scholz, Chris; Smith, Bruce; Smith, Thomas; Zimmerman, Paul

    2010-04-01

    Research has been conducted to develop alternatives to chemically amplified 193 nm photoresist materials that will be able to achieve the requirements associated with sub-32 nm device technology. New as well as older photoresist design concepts for non-chemically amplified 193 nm photoresists that have the potential to enable improvements in line edge roughness while maintaining adequate sensitivity, base solubility, and dry etch resistance for high volume manufacturing are being explored. The particular platforms that have been explored in this work include dissolution inhibitor photoresist systems, chain scissioning polymers, and photoresist systems based on polymers incorporating formyloxyphenyl functional groups. In studies of two-component acidic polymer/dissolution inhibitor systems, it was found that compositions using ortho-nitrobenzyl cholate (NBC) as the dissolution inhibitor and poly norbornene hexafluoro alcohol (PNBHFA) as the base resin are capable of printing 90 nm dense line/space patterns upon exposure to a 193 nm laser. Studies of chain scission enhancement in methylmethacrylate copolymers showed that incorporating small amounts of absorptive a-cleavage monomers significantly enhanced sensitivity with an acceptable increase in absorbance at 193 nm. Specifically, it was found that adding 3 mol% of α-methyl styrene (α-MS) reduced the dose to clear of PMMA-based resist from 1400 mJ/cm2 to 420 mJ/cm2. Preliminary data are also presented on a direct photoreactive design concept based on the photo-Fries reaction of formyloxyphenyl functional groups in acrylic copolymers.

  20. Tissue measurement using 1064 nm dispersive Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lieber, Chad A.; Wu, Huawen; Yang, William

    2013-03-01

    The use of Raman spectroscopy to provide characterization and diagnosis of biological tissues has shown increasing success in recent years. Most of this work has been performed using near-infrared laser sources such as 785 or 830 nm, in a balance of reduced intrinsic fluorescence in the tissues and quantum efficiency in the silicon detectors often used. However, even at these wavelengths, many tissues still exhibit strong or prohibitive fluorescence, and these wavelengths still cause autofluorescence in many common sampling materials, such as glass. In this study, we demonstrate the use of 1064 nm dispersive Raman spectroscopy for the study of biological tissues. A number of tissues are evaluated using the 1064 nm system and compared with the spectra obtained from a 785 nm system. Sampling materials are similarly compared. These results show that 1064 nm dispersive Raman spectroscopy provides a viable solution for measurement of highly fluorescent biological tissues such as liver and kidney, which are difficult or impossible to extract Raman at 785 nm.

  1. Magneto-optical trap for metastable helium at 389 nm

    SciTech Connect

    Koelemeij, J.C.J.; Stas, R.J.W.; Hogervorst, W.; Vassen, W.

    2003-05-01

    We have constructed a magneto-optical trap (MOT) for metastable triplet helium atoms utilizing the 2 {sup 3}S{sub 1}{yields}3 {sup 3}P{sub 2} line at 389 nm as the trapping and cooling transition. The far-red-detuned MOT (detuning {delta}=-41 MHz) typically contains few times 10{sup 7} atoms at a relatively high ({approx}10{sup 9} cm{sup -3}) density, which is a consequence of the large momentum transfer per photon at 389 nm and a small two-body loss rate coefficient (2x10{sup -10} cm{sup 3}/s<{beta}<1.0x10{sup -9} cm{sup 3}/s). The two-body loss rate is more than five times smaller than in a MOT on the commonly used 2 {sup 3}S{sub 1}{yields}2 {sup 3}P{sub 2} line at 1083 nm. Furthermore, laser cooling at 389 nm results in temperatures somewhat lower than those achieved using 1083 nm. The 389-nm MOT exhibits small losses due to two-photon ionization, which have been investigated as well.

  2. High-index nanocomposite photoresist for 193-nm lithography

    NASA Astrophysics Data System (ADS)

    Bae, Woo Jin; Trikeriotis, Makros; Rodriguez, Robert; Zettel, Michael F.; Piscani, Emil; Ober, Christopher K.; Giannelis, Emmanuel P.; Zimmerman, Paul

    2009-03-01

    In immersion lithography, high index fluids are used to increase the numerical aperture (NA) of the imaging system and decrease the minimum printable feature size. Water has been used in first generation immersion lithography at 193 nm to reach the 45 nm node, but to reach the 38 and 32 nm nodes, fluids and resists with a higher index than water are needed. A critical issue hindering the implementation of 193i at the 32 nm node is the availability of high refractive index (n > 1.8) and low optical absorption fluids and resists. It is critical to note that high index resists are necessary only when a high refractive index fluid is in use. High index resist improves the depth of focus (DOF) even without high index fluids. In this study, high refractive index nanoparticles have been synthesized and introduced into a resist matrix to increase the overall refractive index. The strategy followed is to synthesize PGMEA-soluble nanoparticles and then disperse them into a 193 nm resist. High index nanoparticles 1-2 nm in diameter were synthesized by a combination of hydrolysis and sol-gel methods. A ligand exchange method was used, allowing the surface of the nanoparticles to be modified with photoresist-friendly moieties to help them disperse uniformly in the resist matrix. The refractive index and ultraviolet absorbance were measured to evaluate the quality of next generation immersion lithography resist materials.

  3. Power scaling of laser diode pumped Pr3+:LiYF4 cw lasers: efficient laser operation at 522.6 nm, 545.9 nm, 607.2 nm, and 639.5 nm.

    PubMed

    Gün, Teoman; Metz, Philip; Huber, Günter

    2011-03-15

    We report efficient cw laser operation of laser diode pumped Pr(3+)-doped LiYF4 crystals in the visible spectral region. Using two InGaN laser diodes emitting at λ(P)=443.9 nm with maximum output power of 1 W each and a 2.9-mm-long crystal with a doping concentration of 0.5%, output powers of 938 mW, 418 mW, 384 mW, and 773 mW were achieved for the laser wavelengths 639.5 nm, 607.2 nm, 545.9 nm, and 522.6 nm, respectively. The maximum absorbed pump powers were approximately 1.5 W, resulting in slope efficiencies of 63.6%, 32.0%, 52.1%, and 61.5%, as well as electro-optical efficiencies of 9.4%, 4.2%, 3.8%, and 7.7%, respectively. Within these experiments, laser diode-pumped laser action at 545.9 nm was demonstrated for what is believed to be the first time. PMID:21403756

  4. High-performance 193nm photoresists based on fluorosulfonamide

    NASA Astrophysics Data System (ADS)

    Li, Wenjie; Chen, Kuang-Jung; Kwong, Ranee; Lawson, Margaret C.; Khojasteh, Mahmoud; Popova, Irene; Varanasi, P. Rao; Shimokawa, Tsutomu; Yamaguchi, Yoshikazu; Kusumoto, Shiro; Sugiura, Makoto; Kawakami, Takanori; Slezak, Mark; Dabbagh, Gary; Liu, Zhi

    2007-03-01

    The combination of immersion lithography and reticle enhancement techniques (RETs) has extended 193nm lithography into the 45nm node and possibly beyond. In order to fulfill the tight pitch and small critical dimension requirements of these future technology nodes, the performance of 193nm resist materials needs to further improve. In this paper, a high performance 193nm photoresist system based on fluorosulfonamide (FSM) is designed and developed. The FSM group has good transparency at 193nm. Compared to the commonly used hexafluoroalcohol (HFA) group, the trifluoromethyl sulfonamide (TFSM) functionality has a lower pKa value and contains less fluorine atoms. Polymers containing the TFSM functionality have exhibited improved dissolution properties and better etch resistance than their HFA counterparts. Resists based on the FSM-containing polymers have shown superior lithographic performance for line, trench and contact hole levels under the 45nm node exposure conditions. In addition, FSM resists have also demonstrated excellent bright field and dark field compatibility and thereby make it possible to use one resist for both bright field and dark field level applications. The structure, property and lithographic performance of the FSM resist system are reported.

  5. Radiation therapy

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/001918.htm Radiation therapy To use the sharing features on this page, please enable JavaScript. Radiation therapy uses high-powered x-rays, particles, or ...

  6. Theoretical and experimental investigations of nanosecond 177.3 nm deep-ultraviolet light by second harmonic generation in KBBF

    NASA Astrophysics Data System (ADS)

    Yang, F.; Wang, Z.; Zhou, Y.; Li, F.; Xu, J.; Xu, Y.; Cheng, X.; Lu, Y.; Bo, Y.; Peng, Q.; Cui, D.; Zhang, X.; Wang, X.; Zhu, Y.; Xu, Z.

    2009-08-01

    We have presented theoretical and experimental investigations of nanosecond (ns) deep-ultraviolet (DUV) 177.3 nm radiation by means of second harmonic generation (SHG) from a frequency-tripled Nd:YAG laser (355 nm, 49 ns and 10 kHz) in KBe2BO3F2 (KBBF) nonlinear crystal for the first time. A DUV KBBF-SHG numerical model, accounting for linear absorption, pump depletion, beam spatial birefringent walk-off and diffraction, is performed in the Gaussian approximation of spatial and temporal profiles. In the experiment, a maximum average output power of 14.1 mW at 177.3 nm was obtained. The dependence of 177.3 nm output power on the 355 nm pump power was simulated. The calculated results are in good agreement with the measured data. We used the model further to investigate the optical conversion efficiency, pulse width, beam spatial intensity profile and beam quality factor of the generated 177.3 nm light, in particular the effect of beam birefringent walk-off.

  7. Radiation Exposure

    MedlinePlus

    Radiation is energy that travels in the form of waves or high-speed particles. It occurs naturally in sunlight. Man-made radiation is used in X-rays, nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a ...

  8. A comparative study of atmospheric aerosol effect on UV-B erythemal dosage at Delhi and Port Blair site, India.

    NASA Astrophysics Data System (ADS)

    Singh, Risal; Tanwar, R. S.; Srivastava, M. K.; Singh, S.

    The effect of solar ultraviolet radiation on human skin is a matter of human concern and wide interest in scientific community during last few decades National Physical Laboratory NPL New Delhi India initiated the solar UV-B radiation 280- 320nm intensities studies all over the Indian mainland and over Antarctica since 1980s For Delhi site continuous measurement of the UV-B has been done for the last 20 years along with sporadic field campaigns at various mainland islands and oceanic sites The atmospheric aerosol optical depth in visible and near infrared regions has also been done along with UV-B observations for many locations One such campaign has been done at Port Blair Port Blair Andaman Islands 11 67 N 92 72 E 78m amsl during March 2002 The present work emphasizes the results of this field campaign as a relatively cleaner site and its comparison with urban polluted location -- Delhi 28 4 N 77 1 E 216m amsl The observations at both sites were taken under clear sky conditions and the column atmospheric ozone values were almost similar The UV-B measurements were carried out by Erythemal Probe International Light Inc USA having interference filter of wavelength band 290-301 nm maximum sensitivity transmission at 297 5 nm The aerosol optical depth AOD was derived from the solar radiation intensity measurements by grating based solid-state spectroradiometer operating in the wavelength range 350-1100 nm International Light Inc USA Satellite based measurements were also seen for AOD Results show an average global

  9. Recent developments in Fourier domain mode locked lasers for optical coherence tomography: imaging at 1310 nm vs. 1550 nm wavelength.

    PubMed

    Biedermann, Benjamin R; Wieser, Wolfgang; Eigenwillig, Christoph M; Huber, Robert

    2009-07-01

    We report on recent progress in Fourier domain mode-locking (FDML) technology. The paper focuses on developments beyond pushing the speed of these laser sources. After an overview of improvements to FDML over the last three years, a brief analysis of OCT imaging using FDML lasers with different wavelengths is presented. For the first time, high speed, high quality FDML imaging at 1550 nm is presented and compared to a system at 1310 nm. The imaging results of human skin for both wavelengths are compared and analyzed. Sample arm optics, power on the sample, heterodyne gain, detection bandwidth, colour cut levels and sample location have been identical to identify the influence of difference in scattering and water absorption. The imaging performance at 1310 nm in human skin is only slightly better and the results suggest that water absorption only marginally affects the penetration depth in human skin at 1550 nm. For several applications this wavelength may be preferred. PMID:19565537

  10. The Spectrum of Th-Ar Hollow Cathode Lamps in the 691nm to 5804nm region Database

    National Institute of Standards and Technology Data Gateway

    SRD 161 The Spectrum of Th-Ar Hollow Cathode Lamps in the 691nm to 5804nm region Database (Web, free access)   This atlas presents observations of the infra-red (IR) spectrum of a low current Th-Ar hollow cathode lamp with the 2-m Fourier transform spectrometer (FTS) at NIST. These observations establish more than 2400 lines that are suitable for use as wavelength standards in the range 691 nm to 5804 nm. The observations were made in collaboration with the European Southern Observatory (ESO), in order to provide calibration reference data for new high-resolution Echelle spectrographs, such as the Cryogenic High-Resolution IR Echelle Spectrograph ([CRIRES]), ESO's new IR spectrograph at the Very Large Telescope in Chile.

  11. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    PubMed

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range. PMID:26421536

  12. Absolute absorption cross sections of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Parkinson, W. H.; Freeman, D. E.

    1992-01-01

    An account is given of progress of work on absorption cross section measurements of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm. In this wavelength region, the penetration of solar radiation into the Earth's atmosphere is controlled by O2 and O3. The transmitted radiation is available to dissociate trace species such as halocarbons and nitrous oxide. We have recently measured absolute absorption cross sections of O3 in the wavelength region 240-350 nm (Freeman et al., 1985; Yoshino et al., 1988). We apply these proven techniques to the determination of the absorption cross section of O3 at 300 K, 228 K and 195 K throughout the wavelength region 185-240 nm. A paper titled 'Absolute Absorption Cross Section Measurements of Ozone in the Wavelength Region 185-254 nm and the Temperature Dependence' has been submitted for publication in the Journal of Geophysical Research.

  13. Compact Fiber Laser for 589nm Laser Guide Star Generation

    NASA Astrophysics Data System (ADS)

    Pennington, D.; Drobshoff, D.; Mitchell, S.; Brown, A.

    Laser guide stars are crucial to the broad use of astronomical adaptive optics, because they facilitate access to a large fraction of possible locations on the sky. Lasers tuned to the 589 nm atomic sodium resonance can create an artificial beacon at altitudes of 95-105 km, thus coming close to reproducing the light path of starlight. The deployment of multiconjugate adaptive optics on large aperture telescopes world-wide will require the use of three to nine sodium laser guide stars in order to achieve uniform correction over the aperture with a high Strehl value. Current estimates place the minimum required laser power at > 10 W per laser for a continuous wave source, though a pulsed format, nominally 6?s in length at ~ 16.7 kHz, is currently preferred as it would enable tracking the laser through the Na layer to mitigate spot elongation. The lasers also need to be compact, efficient, robust and turnkey. We are developing an all-fiber laser system for generating a 589 nm source for laser-guided adaptive optics. Fiber lasers are more compact and insensitive to alignment than their bulk laser counterparts, and the heat-dissipation characteristics of fibers, coupled with the high efficiencies demonstrated and excellent spatial mode characteristics, make them a preferred candidate for many high power applications. Our design is based on sum-frequency mixing an Er/Yb:doped fiber laser operating at 1583 nm with a 938 nm Nd:silica fiber laser in a periodically poled crystal to generate 589 nm. We have demonstrated 14 W at 1583 nm with an Er/Yb:doped fiber laser, based on a Koheras single frequency fiber oscillator amplified in an IPG Photonics fiber amplifier. The Nd:silica fiber laser is a somewhat more novel device, since the Nd3+ ions must operate on the resonance transition (i.e. 4F3/2-4I9/2), while suppressing ASE losses at the more conventional 1088 nm transition. Optimization of the ratio of the fiber core and cladding permits operation of the laser at room

  14. Microdrilling of metals using femtosecond laser pulses and high average powers at 515 nm and 1030 nm

    NASA Astrophysics Data System (ADS)

    Döring, S.; Ancona, A.; Hädrich, S.; Limpert, J.; Nolte, S.; Tünnermann, A.

    2010-07-01

    We investigate the microdrilling of metals (stainless steel, copper and tungsten) for two different wavelengths, 1030 nm and 515 nm, in the regime of femtosecond laser pulses. An ytterbium-doped fibre CPA system provides high pulse energies (up to 70 μJ) and high repetition rates (up to 800 kHz), corresponding to high average powers of about 50 W, for this experimental study.

  15. Measurements of Photoabsorpton Cross Sections and their Temperature Dependence for CO2 in the 170nm to 200nm Region

    NASA Astrophysics Data System (ADS)

    Parkinson, W. H.; Yoshino, K.

    2001-11-01

    All the photochemical models for the predominately CO2 Martian atmosphere ar e very sensitive to the amount of CO2 and to the values and spectral details of the absorpton cross sections of CO2 in the region 170nm-200nm. Earlier we had measured and published absolute cross sections of CO2 in the region 118.0 nm-175.5 nm at 295K and 195K. We have recently extended these measurements from 170 nm to 200 nm at 300K and 1 95K. The new measurements have been carried out at high resolution with our 6.65 -m normal incidence , photoelectric spectrometer. To measure the weak photoabsorption of the CO2 bands in the wavelength region 170 --200 nm, we required a high column density of the gas. We obtained this by using a multi pass technique, a White cell. The White cell was designed to have a distance of 1.50 m between two main mirrors, and was set for four, double pas ses making a path length of 12.0 m. CO2 gas was frozen in a stainless cylinder immersed in liquid nitrogen, and t he frozen product (dryice) was pumped by the diffusion pump for purification. The CO2 was warmed up slowly and kept in the cylinder at high pressure. The CO2 pressure used in the White cell was varied from 1 to 1000 Torr depend ing on the wavelength region, and was measured with a a capacitance manometer (M KS Baratron, 10 Torr and 1000 Torr). We divided the spectral region into twenty sections of about 1.5 nm extent. At each scan range, another scan was obtained from the emission spectrum of the fourth positive bands of CO for wavelength calibration. We acknowledge funding from NASA, grant NAGS-7859 to Harvard College Observatory.

  16. Imaging performance and challenges of 10nm and 7nm logic nodes with 0.33 NA EUV

    NASA Astrophysics Data System (ADS)

    van Setten, Eelco; Schiffelers, Guido; Psara, Eleni; Oorschot, Dorothe; Davydova, Natalia; Finders, Jo; Depre, Laurent; Farys, Vincent

    2014-10-01

    The NXE:3300B is ASML's third generation EUV system and has an NA of 0.33 and is positioned at a resolution of 22nm, which can be extended down to 18nm and below with off-axis illumination at full transmission. Multiple systems have been qualified and installed at customers. The NXE:3300B succeeds the NXE:3100 system (NA of 0.25), which has allowed customers to gain valuable EUV experience. It is expected that EUV will be adopted first for critical Logic layers at 10nm and 7nm nodes, such as Metal-1, to avoid the complexity of triple patterning schemes using ArF immersion. In this paper we will evaluate the imaging performance of (sub-)10nm node Logic M1 on the NXE:3300B EUV scanner. We will show the line-end performance of tip-to-tip and tip-to-space test features for various pitches and illumination settings and the performance enhancement obtained by means of a 1st round of OPC. We will also show the magnitude of local variations. The Logic M1 cell is evaluated at various critical features to identify hot spots. A 2nd round OPC model was calibrated of which we will show the model accuracy and ability to predict hot spots in the Logic M1 cell. The calibrated OPC model is used to predict the expected performance at 7nm node Logic using off-axis illumination at 16nm minimum half pitch. Initial results of L/S exposed on the NXE:3300B at 7nm node resolutions will be shown. An outlook is given to future 0.33 NA systems on the ASML roadmap with enhanced illuminator capabilities to further improve performance and process window.

  17. Surface modification of polyhedral oligomeric silsesquioxane block copolymer films by 157 nm laser light

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, Evangelia; Kollia, Zoe; Cefalas, Alkiviadis Constantinos; Siokou, Ageliki Elina; Argitis, Panagiotis; Bellas, Vassilios; Kobe, Spomenka

    2009-06-01

    Thin films of ethyl polyhedral oligomeric silsesquioxane (ethyl-POSS) containing polymers at different compositions were chemically modified using laser irradiation at 157 nm. The irradiation caused photodissociation of C-O and C-H bonds followed by the formation of new chemical bonds. The content of Si-O and C-O bonds increased, as did the surface hardness. Vacuum ultraviolet (VUV) absorption, mass spectrometry, x-ray photoelectron spectroscopy, and atomic force microscopy imaging and indentation were used to evaluate the effects of the 157 nm irradiation. The chemical modification was restricted to a thin surface layer. The layer depth was determined by the penetration depth of the 157 nm VUV photons inside the thin copolymer layer. With prolonged VUV irradiation, the absorbance of the polymers increased, eventually becoming saturated. The chemical changes were accompanied by surface hardening, as evidenced by the increase in the Young's modulus from 4 to 24 GPa due to glassification of the irradiated parts. The chemically modified layer acts as a shield against photodissociation and degradation of the deeper portion of the POSS polymer by VUV radiation. Applications include the protection of solar cells on low orbit satellites from solar VUV photons.

  18. Inversion of photometric He+ (30.4 nm) intensities to obtain He+ distributions

    NASA Astrophysics Data System (ADS)

    Garrido, Dante E.; Smith, Roger W.; Marsh, C. A.; Christensen, Andrew B.; Chakrabarti, Supriya

    1993-07-01

    Radiation at He(superscript +) at 30.4 nm, which is emitted close to the Earth, comes from three distinct regions; the ionosphere, the plasmasphere and the polar cap. Published observational data on He(superscript +) 30.4 nm have shown that the intensities from polar regions are relatively smaller than the other regions. Polar emissions are believed to be due to resonant scattering of ion outflow in sunlight. A 1982 rocket flight from Poker Flat, Alaska has shown that line-of-sight 30.4 nm emission rates are relatively strong in the direction of the pole. Since the roll of the rocket afforded many different observing directions, we have used the variety of viewing geometries to extract ionospheric source densities from the photometric intensity data. We have assumed that the He(superscript +) densities vary with distance along dipole field lines according to a particular functional form, and then we proceeded to extract the source densities by a matrix inversion method. The results give density variations over a range of latitudes including samples from each of the regions mentioned above. The method obtains good fits of the observed profiles of intensity versus observation angle.

  19. Diffraction Properties of Periodic Lattices under Free Electron Laser Radiation

    SciTech Connect

    Rajkovic, I.; Busse, G.; Hallmann, J.; More, R.; Petri, M.; Quevedo, W.; Krasniqi, F.; Rudenko, A.; Tschentscher, T.; Stojanovic, N.; Duesterer, S.; Treusch, R.; Tolkiehn, M.; Techert, S.

    2010-03-26

    In this Letter, we report the pioneering use of free electron laser radiation for the investigation of periodic crystalline structures. The diffraction properties of silver behenate single nanocrystals (5.8 nm periodicity) with the dimensions of 20 nmx20 nmx20 {mu}m and as powder with grain sizes smaller than 200 nm were investigated with 8 nm free electron laser radiation in single-shot modus with 30 fs long free electron laser pulses. This work emphasizes the possibility of using soft x-ray free electron laser radiation for these crystallographic studies on a nanometer scale.

  20. Considerations for fine hole patterning for the 7nm node

    NASA Astrophysics Data System (ADS)

    Yaegashi, Hidetami; Oyama, Kenichi; Hara, Arisa; Natori, Sakurako; Yamauchi, Shohei; Yamato, Masatoshi; Koike, Kyohei

    2016-03-01

    One of the practical candidates to produce 7nm node logic devices is to use the multiple patterning with 193-immersion exposure. For the multiple patterning, it is important to evaluate the relation between the number of mask layer and the minimum pitch systematically to judge the device manufacturability. Although the number of the time of patterning, namely LE(Litho-Etch) ^ x-time, and overlay steps have to be reduced, there are some challenges in miniaturization of hole size below 20nm. Various process fluctuations on contact hole have a direct impact on device performance. According to the technical trend, 12nm diameter hole on 30nm-pitch hole will be needed on 7nm node. Extreme ultraviolet lithography (EUV) and Directed self-assembly (DSA) are attracting considerable attention to obtain small feature size pattern, however, 193-immersion still has the potential to extend optical lithography cost-effectively for sub-7nm node. The objective of this work is to study the process variation challenges and resolution in post-processing for the CD-bias control to meet sub-20nm diameter contact hole. Another pattern modulation is also demonstrated during post-processing step for hole shrink. With the realization that pattern fidelity and pattern placement management will limit scaling long before devices and interconnects fail to perform intrinsically, the talk will also outline how circle edge roughness (CER) and Local-CD uniformity can correct efficiency. On the other hand, 1D Gridded-Design-Rules layout (1D layout) has simple rectangular shapes. Also, we have demonstrated CD-bias modification on short trench pattern to cut grating line for its fabrication.

  1. Analysis of Cervical Supernatant Samples Luminescence Using 355 nm Laser

    NASA Astrophysics Data System (ADS)

    Vaitkuviene, A.; Gegzna, V.; Kurtinaitiene, R.; Stanikunas, R.; Rimiene, J.; Vaitkus, J.

    2010-05-01

    The biomarker discovery for accurate detection and diagnosis of cervical carcinoma and its malignant precursors represents one of the current challenges in clinical medicine. Laser induced autofluorescence spectra in cervical smear content were fitted to predict the cervical epithelium diagnosis as a lab off "optical biopsy" method. Liquid PAP supernatant sediment dried on Quartz plate spectroscopy was performed by 355 nm Nd YAG microlaser STA-1 (Standa, Ltd). For comparison a liquid supernatant spectroscopy was formed by laboratory "Perkin Elmer LS 50B spetrometer at 290, 300, 310 nm excitations. Analysis of spectrum was performed by approximation using the multi-peaks program with Lorentz functions for the liquid samples and with Gaussian functions for the dry samples. Ratio of spectral components area to the area under whole experimental curve (SPP) was calculated. The spectral components were compared by averages of SPP using Mann-Whitney U-test in histology groups. Results. Differentiation of Normal and HSIL/CIN2+ cases in whole supernatant could be performed by stationary laboratory lamp spectroscopy at excitation 290 nm and emission >379 nm with accuracy AUC 0,69, Sens 0,72, Spec 0,65. Differentiation Normal versus HSIL/CIN2+ groups in dried enriched supernatant could be performed by 355 nm microlaser excitation at emission 405-424 nm with accuracy (AUC 0,96, Sens 0,91, Spec 1.00). Diagnostic algorithm could be created for all histology groups differentiation under 355 nm excitation. Microlaser induced "optical biopsy "looks promising method for cervical screening at the point of care.

  2. High-brightness 800nm fiber-coupled laser diodes

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Levy, Moshe; Rappaport, Noam; Tessler, Renana; Peleg, Ophir; Shamay, Moshe; Yanson, Dan; Klumel, Genadi; Dahan, Nir; Baskin, Ilya; Shkedi, Lior

    2014-03-01

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. Single emitters offer reliable multi-watt output power from a 100 m lateral emission aperture. By their combination and fiber coupling, pump powers up to 100 W can be achieved from a low-NA fiber pigtail. Whilst in the 9xx nm spectral range the single emitter technology is very mature with <10W output per chip, at 800nm the reliable output power from a single emitter is limited to 4 W - 5 W. Consequently, commercially available fiber coupled modules only deliver 5W - 15W at around 800nm, almost an order of magnitude down from the 9xx range pumps. To bridge this gap, we report our advancement in the brightness and reliability of 800nm single emitters. By optimizing the wafer structure, laser cavity and facet passivation process we have demonstrated QCW device operation up to 19W limited by catastrophic optical damage to the 100 μm aperture. In CW operation, the devices reach 14 W output followed by a reversible thermal rollover and a complete device shutdown at high currents, with the performance fully rebounded after cooling. We also report the beam properties of our 800nm single emitters and provide a comparative analysis with the 9xx nm single emitter family. Pump modules integrating several of these emitters with a 105 μm / 0.15 NA delivery fiber reach 35W in CW at 808 nm. We discuss the key opto-mechanical parameters that will enable further brightness scaling of multi-emitter pump modules.

  3. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm

    NASA Astrophysics Data System (ADS)

    Saarinen, Esa J.; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G.

    2016-03-01

    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the < 40 nm tuning range make the laser a promising tool for medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  4. Fabricating nanopores with diameters of sub-1 nm to 3 nm using multilevel pulse-voltage injection

    PubMed Central

    Yanagi, Itaru; Akahori, Rena; Hatano, Toshiyuki; Takeda, Ken-ichi

    2014-01-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple method for fabricating solid-state nanopores was reported by Kwok, H. et al. and used to fabricate a nanopore (down to 2 nm in size) in a membrane via dielectric breakdown. In the present study, to fabricate smaller nanopores stably—specifically with a diameter of 1 to 2 nm (which is an essential size for identifying each nucleotide)—via dielectric breakdown, a technique called “multilevel pulse-voltage injection” (MPVI) is proposed and evaluated. MPVI can generate nanopores with diameters of sub-1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The generated nanopores can be widened to the desired size (as high as 3 nm in diameter) with sub-nanometre precision, and the mean effective thickness of the fabricated nanopores was 3.7 nm. PMID:24847795

  5. Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions

    NASA Astrophysics Data System (ADS)

    Damodaran, Vani; Rao, Suresh Ranga; Vasa, Nilesh J.

    2016-08-01

    In this paper, a study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented. The caries when imaged with the 840 nm OCT system showed minute demineralisation in the order of 5 μm. The OCT system was also proposed to study the growth of lesion and this was demonstrated by artificially inducing caries with a demineralisation solution of pH 4.8. The progress of carious lesion to a depth of about 50-60 μm after 60 hours of demineralisation was clearly observed with the 840 nm OCT system. The tooth samples were subjected to accelerated demineralisation condition at pH of approximately 2.3 to study the adverse effects and the onset of cavity formation was clearly observed. The restoration of cavity was also studied by employing different restorative materials (filled and unfilled). In the case of restoration without filler material (unfilled), the restoration boundaries were clearly observed. Overall, results were comparable with that of the widely used 1310 nm OCT system. In the case of restoration with filler material, the 1310 nm OCT imaging displayed better imaging capacity due to lower scattering than 840 nm imaging.

  6. Magnetoelastically induced magnetic anisotropy transition in [CoO5nm/CoPt7nm]5 multilayer films

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Harumoto, Takashi; Sannomiya, Takumi; Muraishi, Shinji; Nakamura, Yoshio; Shi, Ji

    2016-06-01

    The magnetic anisotropy transition of [CoO5nm/CoPt7nm]5 multilayer film with respect to post-annealing has been studied systematically. It undergoes a smooth transition from longitudinal magnetic anisotropy (LMA) to perpendicular magnetic anisotropy (PMA) upon annealing and returns backward to LMA at high temperature of 550 °C. The strongest PMA of [CoO5nm/CoPt7nm]5 is achieved after post-annealing at 300 °C and the tolerable post-annealing temperature with strong PMA is up to 400 °C, which indicates this multilayer film could be a potential candidate for the PMA application at middle-high-temperature-region between 300 °C and 400 °C. The mechanism responsible for the transition of magnetic anisotropy has been investigated by analyzing CoO/CoPt interface and CoPt layer internal stress. It is found the effective PMA energy is proportional to the in-plane tensile stress of CoPt layer but is inversely proportional to the roughness of CoO/CoPt interface. Finally, by means of low temperature experiment we demonstrate the magnetic anisotropy transition observed in [CoO5nm/CoPt7nm]5 multilayer film is mainly attributed to the change of CoPt layer in-plane tensile stress.

  7. Research of the Additional Losses Occurring in Optical Fiber at its Multiple Bends in the Range Waves 1310nm, 1550nm and 1625nm Long

    NASA Astrophysics Data System (ADS)

    Yurchenko, A. V.; Gorlov, N. I.; Alkina, A. D.; Mekhtiev, A. D.; Kovtun, A. A.

    2016-01-01

    Article is devoted to research of the additional losses occurring in the optical fiber at its multiple bends in the range waves of 1310 nanometers, 1550 nanometers and 1625 nanometers long. Article is directed on creation of the external factors methods which allow to estimate and eliminate negative influence. The automated way of calculation of losses at a bend is developed. Results of scientific researches are used by engineers of “Kazaktelekom” AS for practical definition of losses service conditions. For modeling the Wolfram|Alpha environment — the knowledge base and a set of computing algorithms was chosen. The greatest losses are noted on wavelength 1310nm and 1625nm. All dependences are nonlinear. Losses with each following excess are multiplicative.

  8. Photoionization branching ratios and vibrational intensity distribution for N2, CO; and CO2 between 53 and 75 nm

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Gardner, J. L.

    1973-01-01

    The probability of radiation producing ions in specific electronic and vibrational levels was documented. For example, when a narrow band-pass of solar ionizing photons is incident on an atmospheric species it is now possible to describe, accurately, how the radiant energy is shared among the various electronic states of the ions produced. The molecules studied were N2, CO, and CO2. These molecules were photoionized by radiation between 53 and 75 nm. The effects of autoionization are discussed and continuum vibrational intensities are tabulated and compared with theoretical Franck-Condon factors where available. The branching ratios and partial cross sections for ionization into various electronic states are tabulated.

  9. Changes in growth, leaf anatomy and pigment concentrations in pea under modulated UV-B field treatments

    SciTech Connect

    Day, T.A.; Howells, B.W.; Ruhland, C.T.

    1995-06-01

    In growth-chamber and greenhouse studies, garden pea is typically quite sensitive to enhanced UV-B radiation (280-320 nm). We assessed whether growth of pea was reduced under more ecologically relevant UV-B enhancements by employing modulated field lampbanks simulating 0, 16 or 24% ozone depletion. We also examined if these UV-B treatments altered leaf anatomy and concentrations of chlorophyll and UV-B-absorbing compounds, and whether this was dependent on leaf age. We used Pisum sativum mutant Argenteum which has an easily detachable epidermis that allowed us to compare concentrations in epidermal and mesophyll tissues. There were no significant UV-B effects on whole-plant growth. Of the 15 leaf-level parameters we examined, UV-B had a strong effect on only two parameters: the ratio of UV-B-absorbing compounds to chlorophyll (which increased with UV-B dose), and stomatal density of the adaxial surface (which decreased with UV-B dose). Chlorophyll concentrations tended to decrease, while the proportion of UV-B-absorbing compounds in the adaxial epidermis tended to increase with UV-B dose (p = 0.11 for both). In contrast to UV-B effects, we found strong leaf-age effects on nearly all parameters except the ratio of UV-B-absorbing compounds to chlorophyll, which remained relatively constant with leaf age.

  10. Protective Effect of Carvacrol on Oxidative Stress and Cellular DNA Damage Induced by UVB Irradiation in Human Peripheral Lymphocytes.

    PubMed

    Aristatile, Balakrishnan; Al-Numair, Khalid S; Al-Assaf, Abdullah H; Veeramani, Chinnadurai; Pugalendi, Kodukkur Viswanathan

    2015-11-01

    Exposure to ultraviolet B (UVB; 280-320 nm) radiation induces the formation of reactive oxygen species (ROS) in the biological system. In this study, we examined the protective effect of carvacrol on UVB-induced lipid peroxidation and oxidative DNA damage with reference to alterations in cellular an-tioxidant status in human lymphocytes. A series of in vitro assays (hydroxyl radical, superoxide, nitric oxide, DPPH (2,2-Diphenyl-1-picryl hydrazyl), and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays) demonstrate antioxidant property of carvacrol in our study. UVB exposure significantly increased thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LHPs), % tail DNA and tail moment; decreased % cell viability and antioxidant status in UVB-irradiated lymphocytes. Treatment with carvacrol 30 min prior to UVB-exposure resulted in a significant decline of TBARS, LHP, % tail DNA, and tail moment and increased % cell viability as carvacrol concentration increased. UVB irradiated lymphocytes with carvacrol alone (at 10 μg/mL) gave no significant change in cell viability, TBARS, LHP, % tail DNA, and tail moment when compared with normal lymphocytes. On the basis of our results, we conclude that carvacrol, a dietary antioxidant, mediates its protective effect through modulation of UVB-induced ROS. PMID:26768646

  11. Interactions of photosynthesis with genome size and function.

    PubMed

    Raven, John A; Beardall, John; Larkum, Anthony W D; Sánchez-Baracaldo, Patricia

    2013-07-19

    Photolithotrophs are divided between those that use water as their electron donor (Cyanobacteria and the photosynthetic eukaryotes) and those that use a different electron donor (the anoxygenic photolithotrophs, all of them Bacteria). Photolithotrophs with the most reduced genomes have more genes than do the corresponding chemoorganotrophs, and the fastest-growing photolithotrophs have significantly lower specific growth rates than the fastest-growing chemoorganotrophs. Slower growth results from diversion of resources into the photosynthetic apparatus, which accounts for about half of the cell protein. There are inherent dangers in (especially oxygenic) photosynthesis, including the formation of reactive oxygen species (ROS) and blue light sensitivity of the water spitting apparatus. The extent to which photolithotrophs incur greater DNA damage and repair, and faster protein turnover with increased rRNA requirement, needs further investigation. A related source of environmental damage is ultraviolet B (UVB) radiation (280-320 nm), whose flux at the Earth's surface decreased as oxygen (and ozone) increased in the atmosphere. This oxygenation led to the requirements of defence against ROS, and decreasing availability to organisms of combined (non-dinitrogen) nitrogen and ferrous iron, and (indirectly) phosphorus, in the oxygenated biosphere. Differential codon usage in the genome and, especially, the proteome can lead to economies in the use of potentially growth-limiting elements. PMID:23754816

  12. In vitro germination characteristics of maize pollen to detect biological activity of environmental pollutants.

    PubMed Central

    Pfahler, P L

    1981-01-01

    In vitro pollen germination was examined as a method to determine the mutagenic and physiological effects of environmental pollutants on higher organisms. Results were presented indicating that mutations could be distinguished by their in vitro germination characteristics if sporophytes homozygous for the mutated allele were tested. The addition of agents directly into the in vitro medium was shown to be an effective method to assess their physiological effects. The exposure of pollen grains during the in vitro germination process to ultraviolet radiation in the B range (280-320 nm) was found to produce little or no change in the germination or ruptured percentage but a sharp decrease in pollen tube growth after 1 hr. In vitro pollen germination appears to be a valuable method to examine the mutation types and physiological effects produced by a broad range of environmental pollutants. In fact, since in vitro germination is related to reproduction and gene transmission, the biological activity of these agents on in vitro germination should be tested routinely to determine their possible effects on food production and gene frequency changes in future generations. Images FIGURE 1. FIGURE 3. PMID:7460877

  13. Protective effect of tropical highland blackberry juice (Rubus adenotrichos Schltdl.) against UVB-mediated damage in human epidermal keratinocytes and in a reconstituted skin equivalent model.

    PubMed

    Calvo-Castro, Laura; Syed, Deeba N; Chamcheu, Jean C; Vilela, Fernanda M P; Pérez, Ana M; Vaillant, Fabrice; Rojas, Miguel; Mukhtar, Hasan

    2013-01-01

    Solar ultraviolet (UV) radiation, particularly its UVB (280-320 nm) spectrum, is the primary environmental stimulus leading to skin carcinogenesis. Several botanical species with antioxidant properties have shown photochemopreventive effects against UVB damage. Costa Rica's tropical highland blackberry (Rubus adenotrichos) contains important levels of phenolic compounds, mainly ellagitannins and anthocyanins, with strong antioxidant properties. In this study, we examined the photochemopreventive effect of R. adenotrichos blackberry juice (BBJ) on UVB-mediated responses in human epidermal keratinocytes and in a three-dimensional (3D) reconstituted normal human skin equivalent (SE). Pretreatment (2 h) and posttreatment (24 h) of normal human epidermal keratinocytes (NHEKs) with BBJ reduced UVB (25 mJ cm(-2))-mediated (1) cyclobutane pyrimidine dimers (CPDs) and (2) 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation. Furthermore, treatment of NHEKs with BBJ increased UVB-mediated (1) poly(ADP-ribose) polymerase cleavage and (2) activation of caspases 3, 8 and 9. Thus, BBJ seems to alleviate UVB-induced effects by reducing DNA damage and increasing apoptosis of damaged cells. To establish the in vivo significance of these findings to human skin, immunohistochemistry studies were performed in a 3D SE model, where BBJ was also found to decrease CPDs formation. These data suggest that BBJ may be developed as an agent to ameliorate UV-induced skin damage. PMID:23711186

  14. Photo-protective effect of americanin B against ultraviolet B-induced damage in cultured human keratinocytes.

    PubMed

    Zheng, Jian; Piao, Mei Jing; Kim, Ki Cheon; Yao, Cheng Wen; Cha, Ji Won; Shin, Jennifer H; Yoo, Suk Jae; Hyun, Jin Won

    2014-11-01

    Excessive ultraviolet (UV) radiation, a constituent of sunlight, can induce multiple types of skin damage. We recently demonstrated that americanin B, a lignin compound, protected cells against hydrogen peroxide (H2O2)-induced damage by exerting antioxidant effects and inhibiting apoptosis. In this study, we investigated the ability of americanin B to protect against cell injury induced by UVB (280-320nm), the most harmful UV wavelengths, in human HaCaT keratinocytes. Americanin B absorbed UVB, eliminated UVB-induced intracellular reactive oxygen species (ROS), and decreased the extent of UVB-induced oxidative modification of lipids, proteins, and DNA. In addition, americanin B inhibited UVB-induced apoptosis, as indicated by reductions in apoptotic body formation and DNA fragmentation. Furthermore, americanin B reversed the depolarization of the mitochondrial membrane induced by UVB exposure. These protective activities were associated with down-regulation of apoptosis-promoting proteins, Bax, caspase-9, and caspase-3 and up-regulation of an apoptosis inhibitor, Bcl-2. These results suggest that americanin B can protect human keratinocytes against UVB-induced cell damage. PMID:25461549

  15. How does the 'ancient' asexual Philodina roseola (Rotifera: Bdelloidea) handle potential UVB-induced mutations?

    PubMed

    Fischer, Claus; Ahlrichs, Wilko H; Buma, Anita G J; van de Poll, Willem H; Bininda-Emonds, Olaf R P

    2013-08-15

    Like other obligate asexuals, bdelloid rotifers are expected to suffer from degradation of their genomes through processes including the accumulation of deleterious mutations. However, sequence-based analyses in this regard remain inconclusive. Instead of looking for historical footprints of mutations in these ancient asexuals, we directly examined the susceptibility and ability to repair point mutations by the bdelloid Philodina roseola by inducing cyclobutane-pyrimidine dimers (CPDs) via exposure to UVB radiation (280-320 nm). For comparison, we performed analogous experiments with the facultative asexual monogonont rotifer Brachionus rubens. Different strategies were found for the two species. Philodina roseola appeared to shield itself from CPD induction through uncharacterized UV-absorbing compounds and, except for the genome reconstruction that occurs after desiccation, was largely unable to repair UVB-induced damage. By contrast, B. rubens was more susceptible to UVB irradiation, but could repair all induced damage in ~2 h. In addition, whereas UV irradiation had a significant negative impact on the reproductive output of P. roseola, and especially so after desiccation, that of B. rubens was unaffected. Although the strategy of P. roseola might suffice under natural conditions where UVB irradiation is less intense, the lack of any immediate CPD repair mechanisms in this species remains perplexing. It remains to be investigated how typical these results are for bdelloids as a group and therefore how reliant these animals are on desiccation-dependent genome repair to correct potential DNA damage given their obligate asexual lifestyle. PMID:23619410

  16. Radiation proctopathy.

    PubMed

    Grodsky, Marc B; Sidani, Shafik M

    2015-06-01

    Radiation therapy is a widely utilized treatment modality for pelvic malignancies, including prostate cancer, rectal cancer, and cervical cancer. Given its fixed position in the pelvis, the rectum is at a high risk for injury secondary to ionizing radiation. Despite advances made in radiation science, up to 75% of the patients will suffer from acute radiation proctitis and up to 20% may experience chronic symptoms. Symptoms can be variable and include diarrhea, bleeding, incontinence, and fistulization. A multitude of treatment options exist. This article summarizes the latest knowledge relating to radiation proctopathy focusing on the vast array of treatment options. PMID:26034407

  17. High-average-power (15-W) 255-nm source based on second-harmonic generation of a copper laser master oscillator power amplifier system in cesium lithium borate

    NASA Astrophysics Data System (ADS)

    Brown, Daniel J. W.; Withford, Michael J.

    2001-12-01

    We have generated 15 W of UV (255-nm) radiation with an optical conversion efficiency of 28% by frequency doubling the 510.6-nm output of a high-beam-quality, high-power copper laser system in cesium borate lithium (CLBO). We found that the superior performance of CLBO relative to β-barium borate is attributable largely to the small UV absorption and wide temperature acceptance bandwidth of CLBO, which reduces thermal dephasing during high-power UV generation.

  18. Performance of multilayer optical coatings under long-term 532nm laser exposure

    NASA Astrophysics Data System (ADS)

    Poulios, D.; Konoplev, O.; Chiragh, F.; Vasilyev, A.; Stephen, M.; Strickler, K.

    2013-11-01

    The effects of long-term exposure to high intensity 532 nm radiation on various dielectric-coated optics are studied. To investigate potential photodarkening effects on optical surfaces, an accelerated life test platform was constructed where optics were exposed to 532 nm radiation from a short-pulse, high repetition rate fiber amplifier at total doses up to 1 trillion shots. The first run of trillion-shot tests were conducted on e-beam deposited and ion beam sputtering (IBS) coated high reflecting mirrors with onsurface intensities ranging from 1.0-1.4 GW/cm2. It was found that the e-beam coated mirrors failed catastrophically at less than 150 billion shots, while the IBS coated mirror was able to complete the trillionshot test with no measurable loss of reflectivity. Profiling the IBS mirror surface with a high-resolution white light interferometer post-irradiation revealed a ~10 nm high photocontamination deposit at the irradiation site that closely matched the intensity profile of the laser spot. Trillion-shot surface exposure tests were also conducted at multiple surface sites of an LBO frequency doubling crystal at ~1.5 GW/cm2 at multiple surface sites. The transmitted power and on-surface beam size were monitored throughout the tests, and periodic measurements of the beam quality and waist location of the transmitted light were also made using an M2 meter. No changes in transmitted power or M2 were observed in any of the tests, but 3D surface profiling revealed laser-induced contamination deposits at each site tested.

  19. Ultraviolet radiation effects

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.

    1989-01-01

    Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

  20. Observation of Quiet Limb in He I 1083.0 nm, H Paschen alpha1281.8 nm and H Brackett gamma 2166.1 nm lines

    NASA Astrophysics Data System (ADS)

    Prasad Choudhary, Debi

    2016-05-01

    In this paper, we shall present the results of an observational study of the quiet solar limb in the near infrared lines using the New IR Array Camera (NAC) and the vertical spectrograph at the focal plane of McMath-Pierce telescope. The NAC, at the exit port of the spectrograph, was used to record the limb spectrum in HeI 1083.0 nm, Hydrogen Paschen 1281.8 nm and Brackett 2165.5 nm wavelength regions. The NAC is a 1024x1024 InSb Alladin III Detector operating over 1-5 micron range with high density sampling at 0.018 arc second/pixel. The all-reflective optical train minimizes number of surfaces and eliminates ghosts leading to low scatter, ghost-free optics. The close-cycle cryogenic provides a stable cooling environment over six hour period with an accuracy of 0.01K leading to low dark current. The low read out noise combined with low scattered light and dark current makes NAC an ideal detector for making high quality infrared spectral observations of solar limb. The limb spectrums were obtained by placing the spectrograph slit perpendicular to the limb at an interval of 10 degrees around the solar disk. We shall report the intensity profile, line-of-sight velocity and line width distribution around the sun derived from the spectra along the slit.

  1. Radiation hydrodynamics

    SciTech Connect

    Pomraning, G.C.

    1982-12-31

    This course was intended to provide the participant with an introduction to the theory of radiative transfer, and an understanding of the coupling of radiative processes to the equations describing compressible flow. At moderate temperatures (thousands of degrees), the role of the radiation is primarily one of transporting energy by radiative processes. At higher temperatures (millions of degrees), the energy and momentum densities of the radiation field may become comparable to or even dominate the corresponding fluid quantities. In this case, the radiation field significantly affects the dynamics of the fluid, and it is the description of this regime which is generally the charter of radiation hydrodynamics. The course provided a discussion of the relevant physics and a derivation of the corresponding equations, as well as an examination of several simplified models. Practical applications include astrophysics and nuclear weapons effects phenomena.

  2. Upper-troposphere and lower-stratosphere water vapor retrievals from the 1400 and 1900 nm water vapor bands

    NASA Astrophysics Data System (ADS)

    Kindel, B. C.; Pilewskie, P.; Schmidt, K. S.; Thornberry, T.; Rollins, A.; Bui, T.

    2015-03-01

    Measuring water vapor in the upper troposphere and lower stratosphere is difficult due to the low mixing ratios found there, typically only a few parts per million. Here we examine near-infrared spectra acquired with the Solar Spectral Flux Radiometer (SSFR) during the first science phase of the NASA Airborne Tropical TRopopause EXperiment (ATTREX). From the 1400 and 1900 nm absorption bands we infer water vapor amounts in the tropical tropopause layer and adjacent regions between altitudes of 14 and 18 km. We compare these measurements to solar transmittance spectra produced with the MODerate resolution atmospheric TRANsmission (MODTRAN) radiative transfer model, using in situ water vapor, temperature, and pressure profiles acquired concurrently with the SSFR spectra. Measured and modeled transmittance values agree within 0.002, with some larger differences in the 1900 nm band (up to 0.004). Integrated water vapor amounts along the absorption path lengths of 3 to 6 km varied from 1.26 × 10-4 to 4.59 × 10-4 g cm-2. A 0.002 difference in absorptance at 1367 nm results in a 3.35 × 10-5 g cm-2 change of integrated water vapor amounts; 0.004 absorptance change at 1870 nm results in 5.50 × 10-5 g cm-2 of water vapor. These are 27% (1367 nm) and 44% (1870 nm) differences at the lowest measured value of water vapor (1.26 × 10-4 g cm-2) and 7% (1367 nm) and 12% (1870 nm) differences at the highest measured value of water vapor (4.59 × 10-4 g cm-2). A potential method for extending this type of measurement from aircraft flight altitude to the top of the atmosphere is discussed.

  3. Upper-troposphere and lower-stratosphere water vapor retrievals from the 1400 and 1900 nm water vapor bands

    NASA Astrophysics Data System (ADS)

    Kindel, B. C.; Pilewskie, P.; Schmidt, K. S.; Thornberry, T.; Rollins, A.; Bui, T.

    2014-10-01

    Measuring water vapor in the upper troposphere and lower stratosphere is difficult due to the low mixing ratios found there, typically only a few parts per million. Here we examine near infrared spectra acquired with the Solar Spectral Flux Radiometer during the first science phase of the NASA Airborne Tropical Tropopause EXperiment. From the 1400 and 1900 nm absorption bands, we infer water vapor amounts in the tropical tropopause layer and adjacent regions between 14 and 18 km altitude. We compare these measurements to solar transmittance spectra produced with the MODerate resolution atmospheric TRANsmission (MODTRAN) radiative transfer model, using in situ water vapor, temperature, and pressure profiles acquired concurrently with the SSFR spectra. Measured and modeled transmittance values agree within 0.002, with some larger differences in the 1900 nm band (up to 0.004). Integrated water vapor amounts along the absorption path lengths of 3 to 6 km varied from 1.26 × 10-4 to 4.59 × 10-4 g cm-2. A 0.002 difference in absorptance at 1367 nm results in a 3.35 × 10-5 g cm-2 change of integrated water vapor amount, 0.004 absorptance change at 1870 nm results in 5.5 × 10-5 g cm-2 of water vapor. These are 27% (1367 nm) and 44% (1870 nm) differences at the lowest measured value of water vapor (1.26 × 10-4 g cm-2) and 7% (1367 nm) and 12% (1870 nm) differences at the highest measured value of water vapor (4.59 × 10-4 g cm-2). A potential method for extending this type of measurement from aircraft flight altitude to the top of the atmosphere (TOA) is discussed.

  4. Switching Properties of sub-100 nm Perpendicular Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Tryputen, Larysa; Piotrowski, Stephan; Bapna, Mukund; Chien, Chia-Ling; Wang, Weigang; Majetich, Sara; Ross, Caroline

    2015-03-01

    Perpendicular magnetic tunnel junctions (p-MTJs) have great potential for realizing high-density non-volatile memory and logic devices. It is critical to solve scalability problem to implement such devices, to achieve low resistance area and to reduce switching current density while maintaining thermal stability. We present our recent results on fabrication of high resolution Ta/CoFeB/MgO/CoFeB/Ta p-MTJ devices and characterization of their switching properties as well as topography and current mapping by using nanoscale Conductive Atomic Force Microscopy. Our patterning method is based on using hydrogen silsesquioxane resist mask combined with ion beam etching. It allows to fabricate p-MTJ devices down to 40 nm in diameter while maintaining the magnetic quality of the multilayers. Repeatable, consistent switching behaviour has been observed in the obtained p-MTJ devices of 500 nm down to 40 nm with 10 - 800 mV voltage applied. Switching field increased as device diameter decreased, from 580 Oe at 500 nm (MR = 10%) to 410 Oe at 80 nm (MR = 9%). We discuss the effect of device sizes on the switching properties. This work was supported in part by C-SPIN, one of the six centers of STARnet, a Semiconductor Research Corporation Program sponsored by MARCO and DARPA and in part through the National Science Foundation through NCN-Needs Program, Contract 12207020-EEC.

  5. Coronal Diagnostics from Narrowband Images Around 30.4 nm

    NASA Astrophysics Data System (ADS)

    Andretta, V.; Telloni, D.; Del Zanna, G.

    2012-07-01

    Images taken in the band centered at 30.4 nm are routinely used to map the radiance of the He ii Ly α line on the solar disk. That line is one of the strongest, if not the strongest, line in the EUV observed in the solar spectrum, and one of the few lines in that wavelength range providing information on the upper chromosphere or lower transition region. However, when observing the off-limb corona, the contribution from the nearby Si xi 30.3 nm line can become significant. In this work we aim at estimating the relative contribution of those two lines in the solar corona around the minimum of solar activity. We combine measurements from CDS taken in August 2008 with temperature and density profiles from semiempirical models of the corona to compute the radiances of the two lines, and of other representative coronal lines ( e.g. Mg x 62.5 nm, Si xii 52.1 nm). Considering both diagnosed quantities from line ratios (temperatures and densities) and line radiances in absolute units, we obtain a good overall match between observations and models. We find that the Si xi line dominates the He ii line from just above the limb up to ≈ 2 R ⊙ in streamers, while its contribution to narrowband imaging in the 30.4 nm band is expected to become smaller, even negligible in the corona beyond ≈ 2 - 3 R ⊙, the precise value being strongly dependent on the coronal temperature profile.

  6. NM23 protein in neoplastic and nonneoplastic thyroid tissues.

    PubMed Central

    Bertheau, P.; De La Rosa, A.; Steeg, P. S.; Merino, M. J.

    1994-01-01

    The expression of nm23 gene products has been associated with a lower metastatic potential and better outcome in malignant tumors. We have used immunohistochemistry to study the expression of nm23 protein in thyroid tissues from 101 patients consisting of 78 malignant neoplasms, 13 adenomas, and 10 other benign conditions. Cytoplasmic staining for nm23 protein was identified in normal tissues and in most benign and malignant lesions and did not correlate with either histological type of clinical outcome. Nuclear staining was seen in 93% of normal tissues and in 29% of primary carcinomas of the thyroid and was associated with a longer disease-free survival (P = 0.03). Membranous staining was present in some tumors but absent in normal thyroid. In conclusion, nm23 protein has a combined pattern of distribution among subcellular compartments in thyroid tissues. Although there was no significant association between cytoplasmic or membranous expression and histological type of tumor or survival nm23 nuclear expression may be a useful marker in assessing the evolution of thyroid tumors. Images Figure 1 PMID:8030752

  7. Taking the X Architecture to the 65-nm technology node

    NASA Astrophysics Data System (ADS)

    Sarma, Robin C.; Smayling, Michael C.; Arora, Narain; Nagata, Toshiyuki; Duane, Michael P.; Shah, Santosh; Keston, Harris J.; Oemardani, Shiany

    2004-05-01

    The X Architecture is a new way of orienting the interconnect on an integrated circuit using diagonal pathways, as well as the traditional right-angle, or Manhattan, configuration. By enabling designs with significantly less wire and fewer vias, the X Architecture can provide substantial improvements in chip performance, power consumption and cost. Members of the X Initiative semiconductor supply chain consortium have demonstrated the production worthiness of the X Architecture at the 130-nm and 90-nm process technology nodes. This paper presents an assessment of the manufacturing readiness of the X Architecture for the 65-nm technology node. The extent to which current production capabilities in mask writing, lithography, wafer processing, inspection and metrology can be used is discussed using the results from a 65-nm test chip. The project was a collaborative effort amongst a number of companies in the IC fabrication supply chain. Applied Materials fabricated the 65-nm X Architecture test chip at its Maydan Technology Center and leveraged the technology of other X Initiative members. Cadence Design Systems provided the test structure design and chip validation tools, Dai Nippon Printing produced the masks and Canon"s imaging system was employed for the photolithography.

  8. Multiwatt diode-pumped Yb:YAG thin disk laser continuously tunable between 1018 and 1053 nm.

    PubMed

    Brauch, U; Giesen, A; Karszewski, M; Stewen, C; Voss, A

    1995-04-01

    A new powerful source of broadly (35-nm) tunable laser radiation in the near-infrared (near 1030 nm) wavelength range is presented. Inserting a birefringent filter into a 10-W diode-pumped Yb:YAG thin disk laser resonator gives several watts of narrow-linewidth (0.07-nm) continuously tunable cw output power. By taking advantage of the power scalability of the thin disk concept, even hundreds of watts of tunable power with near-diffraction-limited beam quality and high efficiency are feasible. Generation and amplification of subpicosecond pulses with high average and peak powers are also promising applications of the Yb:YAG thin disk laser. PMID:19859306

  9. Evaluation of Ionospheric Parameters Obtained by Inverting O II 83.4 nm Dayglow Profiles from RAIDS

    NASA Astrophysics Data System (ADS)

    Geddes, G.; Chakrabarti, S.; Cook, T.; Douglas, E. S.

    2014-12-01

    We test ionospheric parameters obtained by inverting O II 83.4 nm dayglow profiles against coincident ground-based measurements of electron density. Limb profiles from the Remote Atmospheric and Ionospheric Detection System (RAIDS) EUV Spectrograph on the International Space Station (ISS) are compared to a radiative transfer model which assumes a Chapman-α electron density profile fit to an independent ground-based measurement.

  10. Future directions in 980-nm pump lasers: submarine deployment to low-cost watt-class terrestrial pumps

    NASA Astrophysics Data System (ADS)

    Gulgazov, Vadim N.; Jackson, Gordon S.; Lascola, Kevin M.; Major, Jo S.; Parke, Ross; Richard, Tim; Rossin, Victor V.; Zhang, Kai

    1999-09-01

    The demands of global bandwidth and distribution are rising rapidly as Internet usage grows. This fundamentally means that more photons are flowing within optical cables. While transmitting sources launches some optical power, the majority of the optical power that is present within modern telecommunication systems originates from optical amplifiers. In addition, modern optical amplifiers offer flat optical gain over broad wavelength bands, thus making possible dense wavelength de-multiplexing (DWDM) systems. Optical amplifier performance, and by extension the performance of the laser pumps that drive them, is central to the future growth of both optical transmission and distribution systems. Erbium-doped amplifiers currently dominate optical amplifier usage. These amplifiers absorb pump light at 980 nm and/or 1480 nm, and achieve gain at wavelengths around 1550 nm. 980 nm pumps achieve better noise figures and are therefore used for the amplification of small signals. Due to the quantum defect, 1480 nm lasers deliver more signal photon per incident photon. In addition, 1480 nm lasers are less expensive than 980 nm lasers. Thus, 1480 nm pump lasers are used for amplification in situations where noise is not critical. The combination of these traits leads to the situation where many amplifiers contain 980 nm lasers to pump the input section of the Er- doped fiber with 1480 nm lasers being used to pump the latter section of Er fiber. This can be thought of as using 980 nm lasers to power an optical pre-amplifier with the power amplification function being pump with 1480 nm radiation. This paper will focus on 980 nm pump lasers and the impact that advances in 980 nm pump technology will have on optical amplification systems. Currently, 980 nm technology is rapidly advancing in two areas, power and reliability. Improving reliability is becoming increasingly important as amplifiers move towards employing more pump lasers and using these pump lasers without redundancy

  11. Comparison of modeled NmE with NmE measured by the Boulder ionosonde near the spring equinox.

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    We present a comparison of the E-layer peak electron number densities, NmE, measured by the Boulder ionosonde during geomagnetically quiet conditions on 10 April 1996 at low solar activity, 2 April 1993 and 9 April 1978 during moderate solar activity conditions, and 10 April 1991 at high solar activity with numerical theoretical model calculations of NmE. Based on this comparison, the modified EUVAC model solar flux is necessary to increase by a factor of 2 at moderate and high solar activity in the wavelength range of 3.2-7.0 nm. If O (+) ( (4) S), O (+) ( (2) D), O (+) ( (2) P), and N (+) ions are not calculated, the value of NmE is decreased up to a factor of 1.12 at solar minimum and up to a factor of 1.23 for the moderate and high solar activity conditions. The production of N _{2} (+) ions by photoelectron-impact ionization of N _{2} increases the value of NmE up to a factor of 1.18 at low solar activity and up to a factor of 1.33 for the moderate and high solar activity levels. The increase in NmE due to the production of O _{2} (+) ions by photoelectron-impact ionization of O _{2} does not exceed 4 percent. A difference between the calculated electron, T _{e}, and neutral, T _{n}, temperatures is less than 1, 4, 20, 70, and 145 K at 105, 110, 120, 130, and 140 km altitude, respectively. Changes in NmE caused by this difference between T _{e} and T _{n} are negligible.

  12. 4.7-W, 255-nm source based on second-harmonic generation of a copper-vapor laser in cesium lithium borate.

    PubMed

    Trickett, R I; Withford, M J; Brown, D J

    1998-02-01

    We have generated 4.7 W of UV (255-nm) radiation with wall plug efficiency of 0.12% by frequency doubling the green (511-nm) output of a kinetically enhanced medium-scale copper-vapor laser (CVL) in cesium lithium borate (CLBO). Frequency doubling in beta -barium borate produced 3.9 W of UV radiation with wall plug efficiency of 0.1%. We found that conversion was better with CLBO because of the reduced constraints on CVL beam quality, less UV absorption, and smaller UV walk-off. PMID:18084455

  13. Difference-frequency mixing in AgGaS(2) by use of a high-power GaAlAs tapered semiconductor amplifier at 860 nm.

    PubMed

    Simon, U; Tittel, F K; Goldberg, L

    1993-11-15

    As much as 47 microW of cw infrared radiation and 89 microW of pulsed infrared radiation, tunable near 4.3 microm, have been generated by mixing the outputs of a high-power tapered semiconductor amplifier at 858 nm (signal wave) and a Ti:Al(2)O(3) laser at 715 nm (pump wave) in AgGaS(2). The GaAlAs tapered traveling-wave amplifier delivered as much as 1.5 W of diffraction-limited cw power into the nonlinear crystal. Output powers, conversion efficiencies, and spectral characteristics of this novel midinfrared source are discussed. PMID:19829451

  14. Guaranteed discovery of the NmSuGra model

    SciTech Connect

    Balazs, Csaba; Carter, Daniel

    2008-11-23

    We analyze the discovery potential of the next-to-minimal supergravity motivated model: NmSuGra. This model is an extension of mSuGra by a gauge singlet, and contains only one additional parameter: {lambda}, the Higgs-singlet-Higgs coupling. NmSuGra solves the {mu}-problem and reduces the fine tuning of mSuGra. After identifying parameter space regions preferred by present experimental data, we show that these regions of NmSuGra are amenable to detection by the combination of the Large Hadron Collider and an upgraded Cryogenic Dark Matter Search. This conclusion holds strictly provided that the more than three sigma discrepancy in the difference of the experimental and the standard theoretical values of the anomalous magnetic moment of the muon prevails in the future.

  15. Sub-5 nm, globally aligned graphene nanoribbons on Ge(001)

    NASA Astrophysics Data System (ADS)

    Kiraly, Brian; Mannix, Andrew J.; Jacobberger, Robert M.; Fisher, Brandon L.; Arnold, Michael S.; Hersam, Mark C.; Guisinger, Nathan P.

    2016-05-01

    Graphene nanoribbons (GNRs) hold great promise for future electronics because of their edge and width dependent electronic bandgaps and exceptional transport properties. While significant progress toward GNR devices has been made, the field has been limited by difficulties achieving narrow widths, global alignment, and atomically pristine GNR edges on technologically relevant substrates. A recent advance has challenged these limits by using Ge(001) substrates to direct the bottom-up growth of GNRs with nearly pristine armchair edges and widths near ˜10 nm via atmospheric pressure chemical vapor deposition. In this work, the growth of GNRs on Ge(001) is extended to ultra-high vacuum conditions, resulting in the realization of GNRs with widths narrower than 5 nm. Armchair graphene nanoribbons oriented along Ge <110> surface directions are achieved with excellent width control and relatively large bandgaps. The bandgap magnitude and electronic uniformity of these sub-5 nm GNRs are well-suited for emerging nanoelectronic applications.

  16. Composition of 15-85 nm particles in marine air

    NASA Astrophysics Data System (ADS)

    Lawler, M. J.; Whitehead, J.; O'Dowd, C.; Monahan, C.; McFiggans, G.; Smith, J. N.

    2014-11-01

    The chemical composition of 15-85 nm diameter particles was measured at Mace Head, Ireland, during May 2011 using the TDCIMS (thermal desorption chemical ionization mass spectrometer). Measurable levels of chloride, sodium, and sulfate were present in essentially all collected samples of these particles at this coastal Atlantic site. Acetaldehyde and benzoic acid were also frequently detected. Concomitant particle hygroscopicity observations usually showed a sea-salt mode and a lower hygroscopicity mode with growth factors near to that of ammonium sulfate. There were many periods lasting from hours to about 2 days during which the 10-60 nm particle number increased dramatically in polar oceanic air. These periods were correlated with the presence of benzoic acid in the particles and an increase in the number of lower hygroscopicity mode particles. Very small (< 10 nm) particles were also present, suggesting that new particle formation contributed to these nanoparticle enhancement events.

  17. Developmental Function of Nm23/awd - A Mediator of Endocytosis

    PubMed Central

    Nallamothu, Gouthami; Dammai, Vincent; Hsu, Tien

    2009-01-01

    The metastasis suppressor gene Nm23 is highly conserved from yeast to human, implicating a critical developmental function. Studies in cultured mammalian cells have identified several potential functions, but many have not been directly verified in vivo. Here we summarize the studies on the Drosophila homologue of the Nm23 gene, named abnormal wing discs (awd), which shares 78% amino acid identity with the human Nm23-H1 and H2 isoforms. These studies confirmed that awd gene encodes a nucleoside diphosphate kinase, and provided strong evidence of a role for awd in regulating cell differentiation and motility via regulation of growth factor receptor signaling. The latter function is mainly mediated by control of endocytosis. This review provides a historical account of the discovery and subsequent analyses of the awd gene. We will also discuss the possible molecular function of the Awd protein that underlies the endocytic function. PMID:19373545

  18. High power narrowband 589 nm frequency doubled fibre laser source.

    PubMed

    Taylor, Luke; Feng, Yan; Calia, Domenico Bonaccini

    2009-08-17

    We demonstrate high-power high-efficiency cavity-enhanced second harmonic generation of an in-house built ultra-high spectral density (SBS-suppressed) 1178 nm narrowband Raman fibre amplifier. Up to 14.5 W 589 nm CW emission is achieved with linewidth Delta nu(589) < 7 MHz in a diffraction-limited beam, with peak external conversion efficiency of 86%. The inherently high spectral and spatial qualities of the 589 nm source are particularly suited to both spectroscopic and Laser Guide Star applications, given the seed laser can be easily frequency-locked to the Na D(2a) emission line. Further, we expect the technology to be extendable, at similar or higher powers, to wavelengths limited only by the seed-pump-pair availability. PMID:19687946

  19. New Vector Spectropolarimetry of Sunspots near 4000nm

    NASA Astrophysics Data System (ADS)

    Penn, Matthew J.; Coulter, Roy; Goode, Philip R.

    2014-06-01

    Magnetic sensitivity of spectral lines increases as the product of the wavelength and the Lande g-factor. While the most magnetically sensitive spectral line known is the Mg I 12318nm line, and observations are often made near 1600nm, little work has been done using solar spectral lines near 4000nmWe report on new solar spectropolarimetric observations at these wavelengths, made at the NSO McMath-Pierce facility with the NAC and at the NJIT New Solar Telescope using CYRA. Several photospheric absorption lines have been used to map a sunspot magnetic field, and molecular line Zeeman splitting has also been observed. Several "negative-g" molecular lines are seen, and an atomic line shows unusual profiles.

  20. High Power 938nm Cladding Pumped Fiber Laser

    SciTech Connect

    Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D; Taylor, L; Hackenberg, W; Bonaccini, D

    2002-12-26

    We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel, which permitted near complete suppression of amplified spontaneous emission at 1088nm. We are presently seeking to scale the output of this laser to 10W. We will discuss the fiber and laser design issues involved in scaling the laser to the 10W power level and present our most recent results.

  1. Novel EUV resist development for sub-14nm half pitch

    NASA Astrophysics Data System (ADS)

    Hori, Masafumi; Naruoka, Takehiko; Nakagawa, Hisashi; Fujisawa, Tomohisa; Kimoto, Takakazu; Shiratani, Motohiro; Nagai, Tomoki; Ayothi, Ramakrishnan; Hishiro, Yoshi; Hoshiko, Kenji; Kimura, Toru

    2015-03-01

    Extreme ultraviolet (EUV) lithography has emerged as a promising candidate for the manufacturing of semiconductor devices at the sub-14nm half pitch lines and spaces (LS) pattern for 7 nm node and beyond. The success of EUV lithography for the high volume manufacturing of semiconductor devices depends on the availability of suitable resist with high resolution and sensitivity. It is well-known that the key challenge for EUV resist is the simultaneous requirement of ultrahigh resolution (R), low line edge roughness (L) and high sensitivity (S). In this paper, we investigated and developed new chemically amplified resist (CAR) materials to achieve sub-14 nm hp resolution. We found that both resolution and sensitivity were improved simultaneously by controlling acid diffusion length and efficiency of acid generation using novel PAG and sensitizer. EUV lithography evaluation results obtained for new CAR on Micro Exposure Tool (MET) and NXE3300 system are described and the fundamentals are discussed.

  2. Cycloolefin-maleic anhydride copolymers for 193-nm resist compositions

    NASA Astrophysics Data System (ADS)

    Rahman, M. D.; Bae, Jun-Bom; Cook, Michelle M.; Durham, Dana L.; Kudo, Takanori; Kim, Woo-Kyu; Padmanaban, Munirathna; Dammel, Ralph R.

    2000-06-01

    Cycloolefin/maleic anhydride systems are a favorable approach to dry etch resistant resists for 193 nm lithography. This paper reports on poly(BNC/HNC/NC/MA) tetrapolymers, from t- butylnorbornene carboxylate (BNC), hydroxyethyl-norbornene carboxylate (HNC), norbornene carboxylic acid (NC) and maleic anhydride (MA). It was found that moisture has to be excluded in the synthesis of these systems if reproducible results are to be obtained. Lithographic evaluation of an optimized, modified polymer has shown linear isolated line resolution down to 100 nm using conventional 193 nm illumination. Possible reactions of the alcohol and anhydride moieties are discussed, and the effect of the anhydride unit on polymer absorbance is discussed using succinnic anhydride as a model compound.

  3. Improved overlay metrology device correlation on 90-nm logic processes

    NASA Astrophysics Data System (ADS)

    Ueno, Atsushi; Tsujita, Kouichirou; Kurita, Hiroyuki; Iwata, Yasuhisa; Ghinovker, Mark; Poplawski, Jorge M.; Kassel, Elyakim; Adel, Mike E.

    2004-05-01

    Isolated and dense patterns were formed at process layers from gate through to back-end on wafers using a 90 nm logic device process utilizing ArF lithography under various lithography conditions. Pattern placement errors (PPE) between AIM grating and BiB marks were characterized for line widths varying from 1000nm to 140nm. As pattern size was reduced, overlay discrepancies became larger, a tendency which was confirmed by optical simulation with simple coma aberration. Furthermore, incorporating such small patterns into conventional marks resulted in significant degradation in metrology performance while performance on small pattern segmented grating marks was excellent. Finally, the data also show good correlation between the grating mark and specialized design rule feature SEM marks, with poorer correlation between conventional mark and SEM mark confirming that new grating mark significantly improves overlay metrology correlation with device patterns.

  4. Full-field imprinting of sub-40 nm patterns

    NASA Astrophysics Data System (ADS)

    Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-03-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL (R)) is a unique patterning method that has been designed from the beginning to enable precise overlay to enable multilevel device fabrication. A photocurable low viscosity resist is dispensed dropwise to match the pattern density requirements of the device, thus enabling patterning with a uniform residual layer thickness across a field and across multiple wafers. Further, S-FIL provides sub-50 nm feature resolution without the significant expense of multi-element projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of imprint masks (templates). For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x imprint masks with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub-32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the imprint mask and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  5. 32 nm imprint masks using variable shape beam pattern generators

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; Schmid, Gerard; Stacey, Nick; Perez, Joseph; Maltabes, John; Resnick, Douglas J.; Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-05-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL ®) is a unique method that has been designed from the beginning to enable precise overlay for creating multilevel devices. A photocurable low viscosity monomer is dispensed dropwise to meet the pattern density requirements of the device, thus enabling imprint patterning with a uniform residual layer across a field and across entire wafers. Further, S-FIL provides sub-100 nm feature resolution without the significant expense of multi-element, high quality projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of templates. For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x templates with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub 32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the template is discussed and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  6. Full phase-shifting methodology for 65-nm node lithography

    NASA Astrophysics Data System (ADS)

    Pierrat, Christophe; Driessen, Frank A. J. M.; Vandenberghe, Geert

    2003-06-01

    A new methodology for completely phase-shifting a poly layout without creating local phase conflicts was proposed for lithographic techniques combining one phase-shifting mask and one binary mask exposure1. Critical and non-critical areas of the layout are identified and phase conflicts are avoided by splitting the shifter regions from non-critical areas to non-critical areas without crossing critical areas. The out-of-phase splits of the shifter regions are removed using the binary exposure. Simulation results and experimental data collected for 90nm technology node show no sign of process latitude loss around the areas where the shifters are split. The overlay latitude is commensurate with 90nm technology scanner requirements (tool to itself). Simulation work shows that the two exposures are balancing each other out of focus in the 45-degree cut regions thus ensuring large focus latitude. The focus latitude reported is larger than the main feature process latitude; this result was confirmed experimentally. A set of phase-shifting design rules commensurate with an aggressive 65nm node technology (140nm pitch) was put together. Under these conditions, we have identified certain types of cuts that should be avoided during the generation of the phase-shifting layout; this is primarily the case for cuts in "elbow" structures which exhibit limited process latitude. Other cuts like line-end cuts will have to be modified. In this case we have proposed a side cut when the line-end is facing a perpendicular line with a minimum spacing. Despite these restrictions, test structures for the 65nm technology node were successfully converted with no phase conflicts. Experimental verification done on test structures using a 0.75 NA, 193nm scanner demonstrates 0.33 k1 capability using the full phase methodology.

  7. Radiation Chemistry

    NASA Astrophysics Data System (ADS)

    Wojnárovits, L.

    Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

  8. Continuous-wave violet generation at 373.5 nm by frequency-doubled power-scaled near-infrared emitting Pr:YAlO3 laser

    NASA Astrophysics Data System (ADS)

    Fibrich, Martin; Jelínková, Helena

    2013-10-01

    We report on a continuous-wave Pr:YAlO3 laser operating at a wavelength of 373.5 nm in a power-scaled resonator arrangement. Violet light generation has been achieved by intracavity frequency doubling of the near-infrared emitting Pr:YAP laser at a fundamental wavelength of 747 nm. For active medium pumping, two GaN laser diodes providing up to 1 W of output power each at 448 nm were used. By employing BBO crystal as a nonlinear medium, more than 46 mW of violet radiation has been obtained.

  9. Improving vacuum-UV (VUV) photolysis of organic compounds in water with a phosphor converted xenon excimer lamp emitting at 193 nm.

    PubMed

    Schulze-Hennings, U; Pötschke, L; Wietor, C; Bringmann, S; Braun, N; Hayashi, D; Linnemann, V; Pinnekamp, J

    2016-01-01

    A novel vacuum ultraviolet excimer lamp emitting light at 193 nm was used to investigate the degradation of organic micropollutants in ultrapure water and wastewater treatment plant (WWTP) effluent. Overall, light at 193 nm proved to be efficient to degrade the investigated micropollutants (diclofenac, diatrizoic acid, sulfamethoxazole). Experiments with WWTP effluent proved the ability of radiation at 193 nm to degrade micropollutants which are hardly removed with commonly used oxidation technologies like ozonation (diatrizoic acid, ethylenediaminetetraacetic acid, perfluorooctanoic acid, and perfluorooctanesulfonic acid). PMID:27533863

  10. Magnetic Behavior of Surface Nanostructured 50-nm Nickel Thin Films

    PubMed Central

    2010-01-01

    Thermally evaporated 50-nm nickel thin films coated on borosilicate glass substrates were nanostructured by excimer laser (0.5 J/cm2, single shot), DC electric field (up to 2 kV/cm) and trench-template assisted technique. Nanoparticle arrays (anisotropic growth features) have been observed to form in the direction of electric field for DC electric field treatment case and ruptured thin film (isotropic growth features) growth for excimer laser treatment case. For trench-template assisted technique; nanowires (70–150 nm diameters) have grown along the length of trench template. Coercive field and saturation magnetization are observed to be strongly dependent on nanostructuring techniques. PMID:21076670

  11. Cost-effective tunable 1310nm DWDM transmitter

    NASA Astrophysics Data System (ADS)

    Chorchos, Łukasz; Turkiewicz, Jarosław P.

    2015-09-01

    The growing demand for higher data rate transmissions in local and metropolitan area networks is main reason of developing effective and inexpensive transmission systems. In this paper, study about the possibility to realize 1310 nm tunable DWDM transmitter using commercially available low-cost DFB lasers is presented. Extensive DFB lasers characterization has been performed which led to establish relationships between laser current, operational temperature, emitted wavelength and power. An algorithm to find the laser settings for a desired wavelength grid has been proposed and tested. Generation of the 1310nm DWDM channels with frequency spacing between 120 and 240GHz has been demonstrated.

  12. Pseudomorphic Single-Quantum-Well Lasers Emit At 980 Nm

    NASA Technical Reports Server (NTRS)

    Larsson, Anders; Forouhar, Siamak; Cody, Jeffrey G.; Lang, Robert J.; Andrekson, Peter A.

    1992-01-01

    Narrow-stripe semiconductor lasers emitting at 980 nm include pseudomorphic In0.2Ga0.8As/GaAs/AlxGa1-xAs graded-index-of-refraction, separate-confinement-heterostructure single quantum well(GRINSCH SQW) with overlaid ridge waveguide. 980 nm chosen as one that yields most efficient pumping because there is no absorption in excited states at this wavelength. Suitable for pumping Er(Sup3+)-doped optical-fiber amplifiers in optical-fiber communication systems and optical phased-array ranging systems.

  13. Determination of transition probability for the 655-nm Tl line.

    NASA Astrophysics Data System (ADS)

    Karabourniotis, D.; Couris, S.; Damelincourt, J. J.

    Studies of high-pressure Hg-Tl I a.c. (50 Hz) arc plasmas have been used to verify the validity of Boltzmann statistics at the moment of maximum electron density (5 ms) by applying LTE criteria. For a known plasma temperature, the transition probability of the optically-thin 655-nm line of Tl was derived from emission measurements by using the self-reversed 535-nm line of Tl as reference [A655 = (3.74±0.37)×106s-1].

  14. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    PubMed

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light. PMID:18084457

  15. Extension of 193 nm dry lithography to 45-nm half-pitch node: double exposure and double processing technique

    NASA Astrophysics Data System (ADS)

    Biswas, Abani M.; Li, Jianliang; Hiserote, Jay A.; Melvin, Lawrence S., III

    2006-10-01

    Immersion lithography and multiple exposure techniques are the most promising methods to extend lithography manufacturing to the 45nm node. Although immersion lithography has attracted much attention recently as a promising optical lithography extension, it will not solve all the problems at the 45-nm node. The 'dry' option, (i.e. double exposure/etch) which can be realized with standard processing practice, will extend 193-nm lithography to the end of the current industry roadmap. Double exposure/etch lithography is expensive in terms of cost, throughput time, and overlay registration accuracy. However, it is less challenging compared to other possible alternatives and has the ability to break through the κ I barrier (0.25). This process, in combination with attenuated PSM (att-PSM) mask, is a good imaging solution that can reach, and most likely go beyond, the 45-nm node. Mask making requirements in a double exposure scheme will be reduced significantly. This can be appreciated by the fact that the separation of tightly-pitched mask into two less demanding pitch patterns will reduce the stringent specifications for each mask. In this study, modeling of double exposure lithography (DEL) with att-PSM masks to target 45-nm node is described. In addition, mask separation and implementation issues of optical proximity corrections (OPC) to improve process window are studied. To understand the impact of OPC on the process window, Fourier analysis of the masks has been carried out as well.

  16. Precise Fabrication of Nanopores with Diameters of Sub-1 nm to 3 nm Using Multilevel Pulse-voltage Injection

    NASA Astrophysics Data System (ADS)

    Yanagi, Itaru; Akahori, Rena; Yokoi, Takahide; Takeda, Ken-Ichi

    2015-03-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple nanopore-fabrication method has been reported that is based on a dielectric breakdown phenomenon of a thin membrane. In this study, to stably fabricate nanopores with diameters of 1 to 2 nm (which is an essential size for distinguishing each nucleotide) via dielectric breakdown, a technique called multilevel pulse-voltage injection (MPVI) is proposed and demonstrated. MPVI uses pulse voltages for generating the nanopores, and the generation of the nanopores is verified by measuring the current through a membrane at low voltage. This method can generate nanopores with diameters of less than 1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The diameter of the generated nanopores can be widened to the desired diameters (up to 3 nm) with sub-nanometre precision. The mean effective thickness of the fabricated nanopores was 3.7 nm. These findings are derived from TEM images of the fabricated nanopores and analyses of ionic-current blockades during single-stranded DNA translocation.

  17. Enhanced particle guiding using supercontinuum radiation

    NASA Astrophysics Data System (ADS)

    Fischer, Pascal; Carruthers, Antonia E.; Volke-Sepulveda, Karen; Wright, Ewan M.; Little, Helen; Brown, Christian T. A.; Sibbett, Wilson; Dholakia, Kishan

    2006-08-01

    We demonstrate the use of supercontinuum radiation to provide enhanced guiding distances of microscopic particles compared to the standard continuous wave or femtosecond lasers. Our technique relies on the chromatic aberration of the lens used to form an elongated focal region within which guiding takes place. The resulting beam profile has been modelled and shows that for a Gaussian input beam, the intensity profile after the lens can be considered as a sum of Gaussians, one for each wavelength but with varying focal position due to dispersion. Our experimental investigations compare radiation from continuous wave (bandwidth <1nm) and femtosecond pulsed (bandwidth > 100nm) lasers as well as supercontinuum radiation (bandwidth > 450nm) and show good agreement with theory.

  18. Lanthanum halide nanoparticle scintillators for nuclear radiation detection

    SciTech Connect

    Guss, Paul; Guise, Ronald; Yuan, Ding; Mukhopadhyay, Sanjoy; O'Brien, Robert; Lowe, Daniel; Kang, Zhitao; Menkara, Hisham; Nagarkar, Vivek V.

    2013-01-01

    Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum tribromide, lanthanum trifluoride, or cerium tribromide. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

  19. Lanthanum halide nanoparticle scintillators for nuclear radiation detection

    SciTech Connect

    Guss, Paul; Guise, Ronald; O'Brien, Robert; Lowe, Daniel; Kang Zhitao; Menkara, Hisham; Nagarkar, Vivek V.

    2013-02-14

    Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

  20. Radiation esophagitis.

    PubMed

    Murro, Diana; Jakate, Shriram

    2015-06-01

    The esophagus is frequently exposed to radiation during treatment of advanced stages of common cancers such as lung, breast, and esophagus. However, symptomatic radiation esophagitis requiring endoscopic and histologic evaluation occurs quite rarely, affecting less than 1% of patients receiving radiation treatment. Symptoms occur acutely, generally within the first 2 months. Patients typically present with nonspecific symptoms such as dysphagia and odynophagia. Endoscopic changes such as erythema and ulceration are also nonspecific and nondiagnostic. Biopsies from affected areas show variable inflammatory changes and radiation-related atypia of endothelial and stromal cells. Such atypia mimics cytomegalovirus cytopathic changes, which are ruled out through absence of immunostaining. Radiation esophagitis is thus clinically unsuspected and endoscopically and histologically quite different from the more common and familiar radiation proctitis for which angioectasia is the predominant finding. PMID:26030254