Active media for high-efficiency neodymium lasers with nonselective pumping

New polymethine dyes (PD) based on benzene [c, d] indole were synthesized. Their spectral and nonlinear optical characteristics in liquid and polymer media have been studied. It was found that the relaxation times τ of the excited state of the new PDs are approximately the same as those of the dye 3274y, which is widely used as a passive Q-switch of neodymium lasers with a generation lengthwave of 1.06 μm. The low sensitivity of τ to changes in the chemical structure of such PDs indicates that the main contribution to the deactivation of the excited state is made by the benzene [c, d] indole heterocycle. High values of the cross section in the range of 1.05-1.08 μm at low relaxation times allow the studied PD to be easily bleached in lasers at low intensities (about 10 MW/cm2). It is established that the photostability of the new PD significantly exceeds that for the dye 3274y. This is because they contain a saturated six-membered ring in the polymethine chain, which is much less reactive than the corresponding five-membered ring of dye 3274u with respect to the photoinitiator of free radicals of UV irradiation. It is shown that the efficiency of Q-switching and mode locking of new passive laser shutters is higher than their analogues based on the dye 3274y.

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Possibility of age-related changes correction in the face and neck skin using laser technology

Vestnik of Russian military medical Academy ◽

10.17816/brmma12197 ◽

2018 ◽

Vol 20 (1) ◽

pp. 29-34

Author(s):

N A Shanina ◽

A V Patrushev ◽

A V Samtsov ◽

V N Plakhov

Keyword(s):

High Efficiency ◽

Medical Personnel ◽

Laser Exposure ◽

Facial Skin ◽

Age Changes ◽

Laser Technology ◽

Neodymium Lasers ◽

Age Related ◽

The Face ◽

Age Related Changes

The possibility of using combined erbium and neodymium lasers to correct the age-related changes in the face and neck skin by the «Fotona» apparatus using the «Fotona 4D» technique was investigated. To evaluate the results of the study in dynamics an index of age-related changes in skin was developed and applied. The results of photographic fixation and ultrasound of the facial and neck skin before and after laser procedures were also compared. It was determined, that the combination of two wavelengths of 2940 nm (erbium laser) and 1064 nm (neodymium laser) and the «Fotona 4D» technique with 4 patented technologies allows to carry out the procedure at the level of superficial, middle and deep structures of the face and neck tissues. Nowadays it is the only technology for non-invasive volumetric reconstruction and facial skin voluminisation, which is the result of a combination of synergistic methods of laser exposure. It was shown that one month after the second procedure of laser treatment, the face skin turgor increased, its dryness, pore severity, quantity and depth of wrinkles decreased, side effects and complications were absent. Ultrasound examination of the facial skin and index of age- related changes assessing in the face skin confirmed the positive dynamics of correction. Thus, the thickness of the skin in the area of nasolabial folds and superciliary arches increased by 0,5 mm (from 1,9 to 2,4 mm), derma by 0,6 mm (0,8 to 1 mm). The index of age-related changes assessing in the facial skin decreased by 10-13 points (before the procedure it was within the range of 20-24 points (average degree of age changes), after the procedure it was 11 points (mild degree of age changes). Thus, the use of combined erbium and neodymium lasers using the «Fotona 4D» technique showed a high efficiency of laser correction of age-related changes in the facial skin. Implemention of modern technologies in practice of dermatological clinics will improve skills of medical personnel on the use of laser technology.

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Microcalorimeters for X-Ray Spectroscopy

International Astronomical Union Colloquium ◽

10.1017/s0252921100107365 ◽

1988 ◽

Vol 102 ◽

pp. 41

Author(s):

E. Silver ◽

C. Hailey ◽

S. Labov ◽

N. Madden ◽

D. Landis ◽

...

Keyword(s):

High Resolution ◽

High Efficiency ◽

Thermal Response ◽

Low Noise ◽

High Resolution Spectroscopy ◽

Superconducting Transition ◽

Sapphire Substrates ◽

Laboratory Plasmas ◽

Adiabatic Demagnetization ◽

Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

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Imaging and diffraction modes in Scanning Transmission Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144814 ◽

1986 ◽

Vol 44 ◽

pp. 684-687

Author(s):

J. M. Cowley ◽

R. Glaisher ◽

J. A. Lin ◽

H.-J. Ou

Keyword(s):

Scanning Transmission Electron Microscopy ◽

High Efficiency ◽

Fiber Optic ◽

Image Intensifier ◽

Detector System ◽

Detector Plane ◽

Secondary Electrons ◽

Transmission Electron ◽

Scanning Transmission ◽

Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

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Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118692 ◽

1985 ◽

Vol 43 ◽

pp. 364-365

Author(s):

K.M. Hones ◽

P. Sheldon ◽

B.G. Yacobi ◽

A. Mason

Keyword(s):

High Efficiency ◽

Lattice Mismatch ◽

Low Cost ◽

Growth Conditions ◽

Nonradiative Recombination ◽

Device Structure ◽

Si Substrates ◽

Transmission Electron ◽

Dislocation Densities ◽

Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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The use of high-resolution FESEM to study solid-state phase transformations and reactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172875 ◽

1994 ◽

Vol 52 ◽

pp. 1028-1029

Author(s):

P. G. Kotula ◽

D. D. Erickson ◽

C. B. Carter

Keyword(s):

Solid State ◽

High Resolution ◽

Phase Transformations ◽

High Efficiency ◽

Sol Gel ◽

Quantitative Information ◽

Solid State Reactions ◽

Critical Dimensions ◽

Backscattered Electrons ◽

Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

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Interlayer confinement synthesis of Ir nanodots/dual carbon as an electrocatalyst for overall water splitting

Journal of Materials Chemistry A ◽

10.1039/d0ta09358k ◽

2020 ◽

Author(s):

Yaru Li ◽

Yu-Quan Zhu ◽

Weili Xin ◽

Song Hong ◽

Xiaoying Zhao ◽

...

Keyword(s):

Water Splitting ◽

Noble Metal ◽

High Efficiency ◽

Overall Water Splitting ◽

Highly Dispersed

Rationally designing low-content and high-efficiency noble metal nanodots offers opportunities to enhance electrocatalytic performances for water splitting. However, the preparation of highly dispersed nanodots electrocatalysts remains a challenge. Herein, we...

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