共查询到20条相似文献,搜索用时 31 毫秒
1.
K. Nagamine 《Hyperfine Interactions》2001,138(1-4):5-13
Since EXAT98 at Ascona, significant progress has been marked for experimental investigations of the fundamental understanding
of muon catalyzed fusion (μCF) phenomena in D–T, D2 and other hydrogen systems. Future progress in the μCF studies is now guaranteed due to the successful launching of advanced
accelerator projects such as JAERI-KEK Joint Proton Accelerator project and RI Beam Factory project at RIKEN. Also, the start
of the next-phase thermal nuclear fusion project of ITER becomes promising so that some future contributions from ITER to
μCF or vice-versa can be expected for various physical or technological aspects of fusion research. The future progress of
μCF studies will also be promoted because of the growth of various other scientific research using muons. The essence of all
these subjects is reviewed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
R.J.H. Clark 《Applied Physics A: Materials Science & Processing》2007,89(4):833-840
The impact of Raman microscopy on the study of artwork and archaeological artefacts is outlined. Important recent case studies
are presented to illustrate the power of the technique to answer – either alone or in conjunction with other techniques –
key questions of great art historical, conservational, cultural, archaeological and scientific interest. Raman microscopy
also offers, via pigment identification, the possibility of testing the attribution of artwork, a matter which should be of
great concern to galleries, auction houses and museums.
PACS 82.80.Gk; 87.64.Je; 87.64.Ti 相似文献
3.
V. Desnica K. Škarić D. Jembrih-Simbuerger S. Fazinić M. Jakšić D. Mudronja M. Pavličić I. Peranić M. Schreiner 《Applied Physics A: Materials Science & Processing》2008,92(1):19-23
The aim of this work was the investigation of pigments from the painted wooden inventory of the pilgrimage church of Saint
Mary of Jerusalem in Trski Vrh – one of the most beautiful late-baroque sacral ensembles in Croatia. Being an object of high
relevance for the national cultural heritage, an extensive research on the wooden polychromy was undertaken in order to work
out a proposal for a conservation treatment. It consists mainly of two painted and gilded layers (the original one from the
18th century and a later one from 1903), partly overpainted during periodic conservation treatments in the past. The approach
was to carry out extensive preliminary in situ pigment investigations using a portable XRF (X-ray fluorescence) device, and
only the problems not resolved by this method on site were further analyzed using sophisticated laboratory equipment. Therefore,
the XRF results acted as a valuable guideline for subsequent targeted sampling actions, thus minimizing the sampling damage.
Important questions not answered by XRF (identification of organic pigments, ultramarine, etc.) were subsequently resolved
using additional ex situ laboratory methods, primarily μ-PIXE (particle-induced X-ray emission) at the nuclear microprobe
of the Rudjer Boskovic accelerator facility as well as μ-Raman spectroscopy at the Institute of the Academy of Fine Arts in
Vienna. It is shown that by the combination of these often complementary methods a thorough characterization of each pigment
can be obtained, allowing for a proper strategy of the conservation treatment.
PACS 89.20.-a; 82.80.Ej; 82.80.Gk 相似文献
4.
Photoacoustic spectroscopy (PAS) is one of the important branches of spectroscopy, which enables one to detect light-induced
heat production following the absorption of pulsed radiation by the sample. As2S3, As2Se3 and GeSe2 exhibit a wide variety of photo-induced phenomena that enable them to be used as optical imaging or storage medium and various
electronic devices, including electro-optic information storage devices and optical mass memories. Therefore, accurate measurement
of thermal properties of semiconducting films is necessary to study the memory density. The thermal conductivity of thin films
of As2S3 (thickness 100 μm and 80 μm), As2Se3 (thickness 100 μm and 80 μm) and GeSe2 (thickness 120 μm and 100 μm) has been measured using PAS technique. Our result shows that the thermal conductivity of thicker films is larger than the
thinner films. This can be explained by the thermal resistance effect between the film and the surface of the substrate.
相似文献
5.
G. Van der Snickt W. De Nolf B. Vekemans K. Janssens 《Applied Physics A: Materials Science & Processing》2008,92(1):59-68
For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials,
a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary
spectroscopic techniques, namely confocal μ-Raman spectroscopy (μ-RS) and μ-X-ray fluorescence spectroscopy (μ-XRF), were
joined in one instrument. The combined μ-XRF and μ-RS device, called PRAXIS unites both complementary techniques in one mobile
setup, which allows μ- and in situ analysis. μ-XRF allows one to collect elemental and spatially-resolved information in a
non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of μ-XRF are
the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can
be detected. As a result μ-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman
microscopy (μ-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some
cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities
of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical
information supplied by synchrotron radiation μ-X-ray diffraction (SR μ-XRD), a highly specific technique.
PACS 33.20.Fb; 61.05.cp; 33.20.Rm; 07.85.Qe; 91.65.An 相似文献
6.
Jiaqi Guo Xinwei Wang Lijun Zhang Tao Wang 《Applied Physics A: Materials Science & Processing》2007,89(1):153-156
In this work, the thermal diffusivity of single polyacrylonitrile (PAN) wires with diameters from 4.62 μm down to 324 nm is
measured by using our recently developed transient electro-thermal technique. The wires span from 23 μm to 126.2 μm in our
measurement. Since PAN wires are dielectric, a thin Au film is coated on the surface of the wires to make them conductive.
In the experiment, a step current (with ∼2 μs rising time) is fed to the sample. The sample is heated and takes a certain
time to reach its steady thermal state. The temperature rising response of the sample is sensed by measuring the resistance
change of the thin Au coating. From the average temperature evolution of the sample, the thermal diffusivity can be extracted.
Three PAN wires with different diameters are synthesized using the electro-spinning technique and are measured to obtain their
thermal diffusivities (around 1.53×10-7 m2/s), which are slightly smaller than the bulk value.
PACS 65.80.+n; 66.30.Xj; 44.10.+i 相似文献
7.
Sister?Daniilia Elpida Minopoulou 《Applied Physics A: Materials Science & Processing》2009,96(3):701-711
The present analytical study focuses on the degradation phenomena observed in fifteenth century wall paintings of the Christ
Antiphonitis monastery in Cyprus. Examination of ten fragments by means of optical microscopy (OM), scanning electron microscopy (SEM/EDS),
μRaman and FTIR spectroscopy revealed smalt discolouration and loss, and transformation of red lead from orange Pb3O4 to black PbO2. The chromatic changes have affected the aesthetic effect of the paintings insofar as these pigments were extensively used.
The mechanisms of smalt weathering, i.e. leaching of alkali and formation of micro-cracks, are interpreted in relation to
its chemical composition and to the aggressive environmental conditions. In addition, it is assumed that red lead degradation
may have been induced not only by the effect of temperature, light and humidity but also by the presence of chlorine salts.
These phenomena of pigment alteration and loss underline the unsuitability of smalt and minium on wall paintings, regardless
of the painting technique (fresco, fresco-secco, secco). 相似文献
8.
M. Brai M. P. Casaletto G. Gennaro M. Marrale T. Schillaci L. Tranchina 《Applied Physics A: Materials Science & Processing》2010,100(3):945-951
In the present work results on the degradation phenomena of stone materials in the Ancient Theatre of Taormina, one of the
most important Greek–Roman monuments of Sicily, are reported. Artificial stone materials in different conservation conditions
were investigated. Samples of salt efflorescences from brick walls and degraded setting mortars were taken from the open gallery
in “summa cavea”. The chemical, physical and structural characterization was performed by means of X-Ray Photoelectron Spectroscopy (XPS),
X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF), both in situ and ex situ. 相似文献
9.
Y.A. Bakhirkin A.A. Kosterev R.F. Curl F.K. Tittel D.A. Yarekha L. Hvozdara M. Giovannini J. Faist 《Applied physics. B, Lasers and optics》2006,82(1):149-154
A nitric oxide (NO) gas sensor based on a thermoelectrically cooled, continuous-wave, distributed feedback quantum cascade
laser operating at 5.45 μm (1835 cm-1) and off-axis integrated cavity output spectroscopy combined with a wavelength-modulation technique was developed to determine
NO concentrations at the sub-ppbv levels that are essential for a number of applications, such as medical diagnostics, environmental
monitoring, and industrial process control. The sensor employs a 50-cm-long high-finesse optical cavity that provides an effective
path length of ∼700 m. A noise equivalent (SNR=1) minimum detection limit of 0.7 ppbv with a 1-s observation time was achieved.
PACS 07.07.Df; 33.20.Ea; 42.62.Fi; 87.64.Je 相似文献
10.
We report the development of a field-deployable infrared laser spectrometer using new commercial diode laser technology at
2.68 μm. The instrument is designed to measure in situ CO2 concentrations open to the atmosphere at ground level. Absorption lines were carefully selected around 2.68 μm to minimize
interferences from neighboring water vapor transitions. We provide details of the instrument design and data processing. The
long term stability of the instrument was evaluated using the Allan variance technique. A preliminary evaluation of the instrument
performance was realized by in situ measurements of CO2 concentration on the rooftop of our laboratory.
PACS 07.57.Ty; 92.70.Cp 相似文献
11.
C. Jollet 《Physics of Atomic Nuclei》2006,69(11):1872-1875
The aim of the OPERA experiment is to provide unambiguous evidence for the ν
μ ↔ ν
τ oscillation by looking at the appearance of ν
τ in a pure ν
μ beam. This oscillation will be sought in the region of the oscillation parameters indicated by the atmospheric neutrino results.
The experiment is part of the CNGS (CERN Neutrino beam to Gran Sasso) project. The ν
μ beam produced at CERN will be sent towards the Gran Sasso underground laboratory, where the OPERA detector is under construction.
The detector, the physics potential, and performance for neutrino oscillation studies including the subleading ν
μ ↔ ν
ε search are presented.
The text was submitted by the author in English. 相似文献
12.
We consider fundamental bounds on the performance of single-particle tracking schemes based on non-imaging, fluorescence modulation
methods. We calculate the noise density of a linearized position estimate arising from photon-counting statistics and find
the optimal estimate of a freely diffusing particle’s position in the presence of this noise. For the experimentally relevant
case of a Gaussian laser rapidly translated in a circular pattern, explicit expressions are derived for the noise density.
Tracking performance limits are obtained by considering the variance in the estimated position of a Brownian particle with
diffusion coefficient D in the presence of a noise density nm, which we find scales generically as (Dnm
2)1/2. For reasonable experimental parameters, a particle with diffusion coefficient D=1 μm2/s cannot be tracked with accuracy better than approximately 100 nm in three dimensions or 80 nm in two dimensions. Using
a combination of exact results and numerical simulation, we construct a ‘phase diagram’ for determining parameter regimes
in which a particle can be tracked in the presence of measurement noise.
PACS 87.64.Tt; 87.64.Ni; 87.15.Vv 相似文献
13.
M. S. Raghu K. Basavaiah P. J. Ramesh Sameer A. M. Abdulrahman K. B. Vinay 《Journal of Applied Spectroscopy》2012,79(1):131-138
A sensitive, precise, and cost-effective UV-spectrophotometric method is described for the determination of pheniramine maleate
(PAM) in bulk drug and tablets. The method is based on the measurement of absorbance of a PAM solution in 0.1 N HCl at 264 nm.
As per the International Conference on Harmonization (ICH) guidelines, the method was validated for linearity, accuracy, precision,
limits of detection (LOD) and quantification (LOQ), and robustness and ruggedness. A linear relationship between absorbance
and concentration of PAM in the range of 2–40 μg/ml with a correlation coefficient (r) of 0.9998 was obtained. The LOD and
LOQ values were found to be 0.18 and 0.39 μg/ml PAM, respectively. The precision of the method was satisfactory: the value
of relative standard deviation (RSD) did not exceed 3.47%. The proposed method was applied successfully to the determination
of PAM in tablets with good accuracy and precision. Percentages of the label claims ranged from 101.8 to 102.01% with the
standard deviation (SD) from 0.64 to 0.72%. The accuracy of the method was further ascertained by recovery studies via a standard
addition procedure. In addition, the forced degradation of PAM was conducted in accordance with the ICH guidelines. Acidic
and basic hydrolysis, thermal stress, peroxide, and photolytic degradation were used to assess the stability-indicating power
of the method. A substantial degradation was observed during oxidative and alkaline degradations. No degradation was observed
under other stress conditions. 相似文献
14.
G. Durry N. Amarouche L. Joly X. Liu B. Parvitte V. Zéninari 《Applied physics. B, Lasers and optics》2008,90(3-4):573-580
The 2.7 μm spectral range is highly suitable for the in situ monitoring of atmospheric H2O using compact balloonborne laser diode spectrometers. Water vapour spectroscopic parameters of the 202
101 and the 413
414 transitions of the ν3 band are revisited in this spectral region using a new distributed-feedback InGaAsSb laser diode emitting at 2.63 μm. Accurate
line strengths are provided which are well adapted for the in situ probing of the middle atmosphere. Our measurements are
thoroughly compared to an existing molecular database, laboratory measurements and ab-initio calculations. A laser hygrometer
was developed for operation from small stratospheric balloons using this new laser diode technology, with emission at 2.6 μm.
The realized sensor is described and results from a recent test-flight are reported.
PACS 07.57.Ty; 92.60 Jq 相似文献
15.
A gas-filled microstrip detector for thermal neutrons has been built and successfully tested in our laboratory. The detector
has an active area of 20 mm × 15 mm and consists of alternate anodes and cathodes of widths 12 μm and 300 μm respectively.
The anode to cathode gap is 150 μm and the pitch is 612 μm. A high resistance, meandering type horizontal strip connects the
anodes at one end and aids in position sensing by charge division method. The detector is tested with gas mixtures3He+Kr (1: 2) and3He+CF4 (2:1) at pressure of 3 atmospheres and using a Pu-Be neutron source. The pulse height spectrum shows energy resolution of
∼8% (FWHM) for the 764 keV peak at anode voltage of 525 V for3He+Kr and ∼15% at anode voltage of 800 V for3He+CF4. Gas gains up to 6.3 × 103 and 3.6 × 103 are obtained respectively with these gas mixtures. The overall efficiency of the
detector along the sensitive length is tested by exposing the active area to neutrons and recording the position spectrum.
The detector shows fairly uniform efficiency (∼45%) over the active length. 相似文献
16.
X.Q. Yan H.J. Yuan J.X. Wang D.F. Liu Z.P. Zhou Y. Gao L. Song L.F. Liu W.Y. Zhou G. Wang S.S. Xie 《Applied Physics A: Materials Science & Processing》2004,79(8):1853-1856
A large amount of Ni2Si nanowires sheathed with amorphous silicon oxide has been generated from Ni substrates, for the first time, by thermal chemical vapor deposition using SiH4 gas at 500 °C. The Ni2Si nanowires obtained possess substantial amounts of branches (about 2-m length) grown on the main stems (about -–30 80nm diameter and -–10 20m length). High-resolution transmission electron microscopy and electron diffraction have revealed the orthorhombic Ni2Si phase and the orientation. At the tail end along the branch grown on a stem an amorphous phase was also observed. The Raman spectrum was further used to characterize the product. A possible growth process of the branched Ni2Si nanowires is briefly discussed. PACS 81.05.Bx; 81.07.Bc; 81.15.Gh; 87.64.Ee; 87.64.Je 相似文献
17.
G. Daminelli S. Pentzien A. Hertwig J. Krüger 《Applied Physics A: Materials Science & Processing》2006,83(1):89-94
Single-pulse damage thresholds of hydrogenated amorphous carbon (a-C:H) films were measured for 8-ns laser pulses at 532-nm wavelength. Layer thicknesses from below the optical penetration depth to above the thermal diffusion length (60 nm–13 μm) were examined. After correction of the damage-threshold values for the fraction of energy effectively absorbed by the material, the damage threshold was found to increase linearly with the layer thickness, also for film thicknesses below the optical penetration depth of a-C:H. The threshold fluence reached the bulk value for a layer thickness equal to the thermal diffusion length. The thermal diffusion coefficient was obtained from fitting the experimental data. Several phenomena like graphitization, blistering, exfoliation, and ablation were observed for different fluence regimes and film thicknesses. PACS 79.20.Ds; 06.60.Jn; 78.66.Jg 相似文献
18.
Adel Bousseksou Sophie Bouchoule Moustafa El Kurdi Martin Strassner Isabelle Sagnes Paul Crozat Joel Jacquet 《Optical and Quantum Electronics》2006,38(15):1269-1278
We report on the design, fabrication, and characterization of InP-based 1.55 μm wavelength large diameter (50 μm) electrically pumped vertical external cavity surface emitting lasers (EP-VECSELs). The hybrid device consists of a half
vertical cavity surface emitting laser (1/2-VCSEL) structure assembled with a concave dielectric external mirror. The 1/2-VCSEL
is monolithically grown on InP substrate and includes a semiconductor Bragg mirror and a tunnel junction for electrical injection.
Buried (BTJ) and ion implanted (ITJ) tunnel junction electrical confinement schemes are compared in terms of their thermal
and electrical characteristics. Lower thermal resistance values are measured for BJT, but reduced current crowding effects
and uniform current injection are evidenced for ITJ. Using the ITJ technique, we demonstrate Room-Temperature (RT) continuous-wave
(CW) single transverse mode laser operation from 50-μm diameter EP-VECSEL devices. We show that the experimental laser optical output versus injected current (L–I) curves are well-reproduced by a simple analytical thermal model, consistent with the thermal resistance measurements performed
on the 1/2-VCSEL structure. Our results indicate that thermal heating is the main mechanism limiting the maximum CW output
power of 50-μm diameter VECSELs, rather than current injection inhomogeneity. 相似文献
19.
Ablation of bulk metals (Al, Cu) has been investigated in situ by means of high-resolution pump-probe photography using pump
laser radiation of pulse duration t
p=80 fs, at wavelength of 820 nm.
Depending on material-specific parameters, qualitatively different ablation phenomena have been observed. Structural analysis
by electron and optical microscopies reveals rosette-like surface structures showing the morphology of the ablated regions.
The temporal development of the ablation dynamics can be conditionally categorized into different characteristic time regions.
Particularly, laser induced melt injection has been observed in the time range of 700 ns to 1.1 μs after the initial laser-metal
interaction. 相似文献
20.
Csaba László Sajti Svea Petersen Ana Menéndez-Manjón Stephan Barcikowski 《Applied Physics A: Materials Science & Processing》2010,101(2):259-264
In-situ functionalization of gold nanoparticles with fluorophore-tagged oligonucleotides is studied by comparing femtosecond
laser ablation in stationary liquid and in biomolecule flow. Femtosecond laser pulses induce significant degradation to sensitive
biomolecules when ablating gold in a stationary solution of oligonucleotides. Contrary, in-situ conjugation of nanoparticles
in biomolecule flow considerably reduces the degree of degradation studied by gel electrophoresis and UV–Vis spectrometry.
Ablating gold with 100 μJ femtosecond laser pulses DNA sequence does not degrade, while the degree of fluorophore tag degradation
was 84% in stationary solution compared to 5% for 1 mL/min liquid flow. It is concluded that femtosecond laser-induced degradation
of biomolecules is triggered by absorption of nanoparticle conjugates suspended in the colloid and not by ablation of the
target. Quenching of nanoparticle size appears from 0.5 μM biomolecule concentration for 0.3 μg/s nanoparticle productivity
indicating the successful surface functionalization. Finally, increasing the liquid flow rate from stationary to 450 mL/min
enhances nanoparticle productivity from 0.2 μg/s to 1.5 μg/s, as increasing liquid flow allows removal of light absorbing
nanoparticles from the ablation zone, avoiding attenuation of subsequent laser photons. 相似文献