共查询到20条相似文献,搜索用时 15 毫秒
1.
A novel LiGdF4 crystal doped with Thulium ions has been grown using the Czochralski technique. Three samples with doping concentrations of 0.3 at.%, 8 at.%, and 12 at.% have been extensively spectroscopically analyzed. We also performed room-temperature preliminary laser experiments, pumping the samples with a laser diode at 792 nm obtaining 53% as maximum slope efficiency with a maximum output power of 205 mW and a minimum lasing threshold of 22 mW. The laser emission spectrum in free running condition typically spans between 1990 and 2018 nm. 相似文献
2.
红外反射光谱的原理和方法 总被引:1,自引:0,他引:1
固体的光学性质是凝聚态物理学中的一类重要问题,它可以用一系列的光学常数进行描写.在实验上,最常用的方法是,测量材料在一个尽可能宽的频率范围内的正入射反射率,然后通过Kramers-Kronig(KK)变换的方法来得到光学常数.文章介绍了傅里叶变换红外反射光谱的原理、仪器组成和一种原位蒸发镀膜技术.这样的方法可以很好地测量包括小尺寸和不规则样品在内的材料从数个毫电子伏至数个电子伏范围内的反射率,因而在研究固体的各种不同的单粒子激发(或集体激发)中起重要的作用. 相似文献
3.
4.
5.
6.
中子星—中子星或中子星—黑洞组成的致密双星系统在发生并合时,潮汐离心、碰撞挤压和吸积反馈等作用会导致约千分之几到百分之几倍太阳质量的物质被抛射到星际空间中。这些抛射物在加热机制的作用下可能达到较高的温度并快速膨胀,从而在紫外光学近红外波段发出一种快速变化的热辐射,即为千新星辐射。决定于抛射物的质量和不透明度,千新星的特征光变时标可估计在天到星期的量级。其辐射光度至少可达10&;amp;lt;sup&;amp;lt;41&;amp;lt;/sup&;amp;lt; erg s&;amp;lt;sup&;amp;lt;-1&;amp;lt;/sup&;amp;lt;的量级,具体决定于热源的性质,包括抛射物中通过快中子俘获过程形成的重元素的放射性衰变和并合产物可能的持续能量释放。千新星现象在2017年8月的GW170817引力波事件中被首次观测证实。 相似文献
7.
8.
9.
F. Allario J. M. Hoell S. J. Katzberg J. C. Larsen 《Applied Physics A: Materials Science & Processing》1980,23(1):47-56
Laser heterodyne spectroscopy (LHS) techniques with semiconductor laser local oscillators (LO) in the 3–30 μm range have the
potential to measure radical gas species in the stratosphere. The goal of this experiment is to measure radical gases from
Spacelab, including ClO, ClONO2, HO2, H2O2, N2O5, and HOCl in solar occulation with vertical resolution ≦2km and vertical range from 10 to 70 km. Sensitivity analyses have
been performed on ClO and O3 to determine design criteria for the LHS instrument. Results show that O3 and ClO vertical profiles can be measured with an accuracy ≧95% and ≧80%, respectively, over the total profile. These accuracies
require the LO to maintain the following characteristics: frequency stability (Δf
w≦20 MHz), single-mode power (P
LO≧500 μW), and minimum frequency drift (≦5 MHz). Laboratory heterodyne measurements performed with semiconductor lasers generated
the same shot-noise photocurrent as CO2 lasers, for comparable single-mode power. “Excess-noise” regions were identified, but could be wavelength controlled by fine
control of operating temperature and injection current. Doppler-shift effects and limited solar occultation measurement times
due to Spacelab orbits should pose minimum mission constraints on the experiment. 相似文献
10.
A. Nieminen J. Huikari A. Jokinen J. Äystö J. Billowes P. Campbell E.C.A. Cochrane 《Hyperfine Interactions》2000,127(1-4):507-510
An ion beam cooler has been constructed and tested at the IGISOL mass separator facility at the University of Jyväskylä. The cooler is designed to improve the ion optical properties of radioactive ion beams produced with fission-, light-ion fusion and heavy ion fusion ion guides. The performance of the device has been tested in off- and on-line conditions. It has been shown that the emittance and energy spread of the ion beam can be decoupled from the ion guide parameters with high transmission efficiency. 相似文献
11.
V. S. Letokhov 《Optics & Laser Technology》1977,9(6):263-272
The three basic methods of linear laser spectroscopy are reviewed: absorption, opto-acoustic, and fluorescence spectroscopy. The characteristics of each method and their areas of application are presented and compared. 相似文献
12.
13.
15.
Percolation theory, the theory of the properties of classical particles interacting with a random medium, is of wide applicability and provides a simple picture exhibiting critical behaviour, the features of which are well understood and amenable to detailed calculation. In this review the concepts of percolation theory and the general features associated with the critical region about the onset of percolation are developed in detail. In particular, several dimensional invariants are examined which make it possible to unify much of the available information, and to extend the insights of percolation theory to processes which have not yet received numerical study. The compilation of the results of percolation theory, both exact and numerical, is believed to be complete through 1970. A selective bibliography is given. In a concluding chapter several recent applications of percolation theory to classical and to quantum mechanical problems are discussed. 相似文献
16.
Herbi Dreiner 《Pramana》1998,51(1-2):123-133
I discuss the theoretical motivations forR-parity violation, review the experimental bounds and outline the main changes in collider phenomenology compared to conservedR-parity. 相似文献
17.
18.
19.
The linear theory of ship hydroelasticity is not yet familiar in naval architecture, yet it provides the most powerful techniques of investigation available today. The background of that theory is explained in very simple terms, by using the concept of a “uniform ship”—that is, of a uniform floating beam. So rudimentary is this idealization of a ship that no claim can be made that numerical results have much practical significance; nevertheless, the underlying ideas are those employed in practical studies and some typical results are given for an actual ship (an old destroyer). 相似文献
20.