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61.
K. Obata K. Sugioka T. Akane N. Aoki K. Toyoda K. Midorikawa 《Applied Physics A: Materials Science & Processing》2001,73(6):755-759
A collinear irradiation system of F2 and KrF excimer lasers for high-quality and high-efficiency ablation of hard materials by the F2 and KrF excimer lasers’ multi-wavelength excitation process has been developed. This system achieves well-defined micropatterning
of fused silica with little thermal influence and little debris deposition. In addition, the dependence of ablation rate on
various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number is examined to investigate
the role of the F2 laser in this process. The multi-wavelength excitation effect is strongly affected by the irradiation timing, and an extremely
high ablation rate of over 30 nm/pulse is obtained between -10 ns and 10 ns of the delay time of F2 laser irradiation. The KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases
with increasing F2 laser fluence. Moreover, the ablation rate shows a linear increase with the logarithm of KrF excimer laser fluence when the
F2 laser is simultaneously irradiated, while single KrF excimer laser ablation shows a nonlinear increase. The ablation mechanism
is discussed based on these results.
Received: 16 July 2001 / Accepted: 27 July 2001 / Published online: 2 October 2001 相似文献
62.
63.
In Raman-Nath diffraction by water, the intensities of even order light beams are selectively enhanced by suspension of microparticles.
The diffracted beams remain for several seconds even after the ultrasonic oscillation stops. These phenomena are elucidated
by assuming the laminar arrangement of micropaticles due to the ultrasonic wave. 相似文献
64.
Ilko K. Ilev Hiroshi Kumagai Koichi Toyoda Deepak Uttamchandani Brian Culshaw 《Optical Review》1997,4(1):A58-A60
An alternative and simple fiber-optic backreflectance sensor method for accurate measurement of either effective focal lengths
of optical elements and short distances using a single-mode optical fiber and cw laser is presented. The method is based on
the intensity sensing of focused backreflectance laser emission and the spatial location of three specific points: the focal
point of the focusing optical element and two object points. The single-mode fiber is a key optical element and serves simultaneously
as a point laser source for testing, an object for projecting and a highly sensitive point receiver of the focused backreflectance
emission. The experimental and analytical results demonstrate the potential of the method for locating the spatial points
and determining the effective focal length with accuracies exceeding 1 μm and 0.5%, respectively, as well as for short distance
measurement with submicron accuracy. 相似文献
65.
Hornfels, and intrusion rocks were studied with electron spin resonance (ESR) as a function of the distance from an intrusion zone in Mino Natural Park, Osaka, Japan. The temperature distribution in metamorphic rocks around an intrusion zone was calculated based on a simplified model of one-dimensional thermal conduction. The age as well as the thermal effect due to an intrusion rock were assessed using ESR signal intensities of paramagnetic defect centers (E’, oxygen-hole, and Al) in quartz grains. Geothermal heating effects are observable more than ten million years later for stable detects such as the E’ center. 相似文献
66.
Yosuke Kawai Toshinobu Hondo Kirk R. Jensen Michisato Toyoda Kentaro Terada 《Journal of the American Society for Mass Spectrometry》2018,29(7):1403-1407
Two different types of data acquisition methods, “averaging mode” and “ion-counting mode”, have been used in a time-of-flight (TOF) mass spectrometry. The most common method is an averaging mode that sums waveform signals obtained from each flight cycle. While it is possible to process many ions arriving at the same TOF in one flight cycle, low-abundance ions are difficult to measure because ion signals are overwhelmed by noises from the detection system. An ion-counting mode is suitable for the detection of such low-concentration ions, but counting loss occurs when two or more ions arrive at the detector within the dead time of the acquisition system. In this study, we introduce a technique that combines two methods to measure target ions with a high concentration difference, i.e., averaging mode and ion-counting mode are used simultaneously for high abundant and trace ions, respectively. By processing waveforms concurrently during data acquisition, one can choose to analyze either or both types of data to achieve a highly quantitative mass spectrum over a wide range of sample concentrations. The result of the argon isotope analysis shows that this method provides a more accurate determination of the isotope ratio compared to averaging mode alone at one-twentieth of the analysis time required by ion-counting alone. 相似文献
67.
Lossless light projection 总被引:1,自引:0,他引:1
A new technique for energy-preserving phase-only light projection is demonstrated. The phase-only encoding is based on an extension of the Zernike phase-contrast method into the domain of full-range [0; 2pi ] phase modulation, breaking the usual small-phase-angle limitation. Controlling the spatial average value of the input-phase pattern and choosing appropriate phase retardation at the phase-contrast filter yield pure-phase-based image formation. Experimental results demonstrate close to 90% energy efficiency. Output intensity levels with magnitudes more than 3.5times that of the input intensity level were measured in the brightest regions of the projected images. 相似文献
68.
[graph: see text] We describe the synthesis of new environmentally sensitive fluorescence probes to elucidate DNA structures. DNA oligonucleotides containing fluorophore dan (6-(dimethylamino)-2-acylnaphthalene)-modified dC or dG were able to monitor the microenvironmental changes in both the major and minor grooves of DNA with a B- to A-DNA conformational transition and RNA hybridization. 相似文献
69.
Takahashi T Tsai FY Li Y Wang H Kondo Y Yamanaka M Nakajima K Kotora M 《Journal of the American Chemical Society》2002,124(18):5059-5067
Selective preparation of pyridine derivatives from two different alkynes and a nitrile was achieved by a novel procedure in which an alkyne and a nitrile couple first to give an azazirconacyclopentadiene followed by reaction with the second alkyne in the presence of 1 equiv of NiCl(2)(PPh(3))(2). This procedure gives only single products of pyridine derivatives from two different symmetrical alkynes and a nitrile. Our novel procedure can be used even with two similar alkyl-substituted alkynes such as 3-hexyne and 4-octyne. Two possible pyridine isomers from 3-hexyne, 4-octyne, and acetonitrile could be completely and independently prepared as single products by this method. The origin of the selectivity comes from the addition order of two different alkynes. This method was applied for the formation of pyridones and iminopyridines using isocyanate and carbodiimide derivatives instead of nitriles, respectively. Reaction of an alkyne with Cp(2)ZrEt(2) and an isocyanate or a carbodiimide gives an azazirconacycle. Treatment of the azazirconacycle with the second alkyne in the presence of 1 equiv of NiCl(2)(PPh(3))(2) gave a pyridone or an iminopyridine derivative. The use of two different unsymmetrical alkynes afforded the pyridine with five different substituents when the first alkyne has a trialkylsilyl group and the second alkyne has a phenyl group as functional groups. On the other hand, azazirconacyclopentadienes reacted with propargyl bromide in the presence of CuCl with excellent regioselectivity to give tetrasubstituted pyridine derivatives as single products. With the assistance of the trialkylsilyl groups, pyridines with all different substituents including H were also prepared. 相似文献
70.
Shouhei Toyoda Yoshifumi Yamaguchi Masataka Hiwatashi Yasuhiko Tomonari Hiroto Murakami Dr. Naotoshi Nakashima Prof. 《化学:亚洲杂志》2007,2(1):145-149
We designed and synthesized 4‐dodecyloxybenzenediazonium tetrafluoroborate ( 1 ), which preferentially reacts with metallic single‐walled carbon nanotubes (SWNTs) by kinetic control. We first determined the suitable experimental conditions for the preferential reaction of 1 with individually dissolved SWNTs by monitoring the decrease in absorbance for the metallic SWNT in the range of 400–650 nm in the absorption spectrum of the SWNTs. The reacted SWNTs were thoroughly rinsed with THF to obtain THF‐insoluble SWNTs. The Raman spectrum of the THF‐insoluble SWNTs showed a strong peak near 180 cm?1, which corresponds to a semiconducting breathing band. The metallic breathing bands (≈220 cm?1) and Breit–Wingner–Fano (BWF) modes (1520 cm?1) corresponding to the metallic SWNTs were much weaker than those of the pristine SWNTs. We also confirmed that metallic peaks in the range of 400–650 nm in the absorption spectrum of THF‐insoluble SWNTs that were individually dissolved in an aqueous micelle of sodium cholate were almost nondetectable. All the results indicate that the THF‐insoluble SWNTs are semiconducting. 相似文献