Near-infrared emission materials

Figure 2.17 ORTEP view of the [Er(L )3(OP(C6F5)3)2] molecule [23c]. (Reprinted with permission from A. Monguzzi, R. Tubino, E. Meinardi et al, Novel Er + perfluorinated complexes for broadband sensitized near infrared emission, Chemistry of Materials, 21, 128-135, 2009. 2009 American Chemical Society.)...

Baek, N.S., Kim, Y.H., Roh, S.-G, et al. (2006) The first inert and photostable encapsulated lanthanide(lll) complexes based on dendritic 9,10-diphenylanthracene Ugands syntUesis, strong near-infrared emission enUancement, and pUotopUysical smdies. Advanced Functional Materials, 16, 1873. 

M. A. Hines, G. D. Scholes, Colloidal PbS Nanocrystals with Size-Tunable Near-Infrared Emission Observation of Post-Synthesis Self-Narrowing of the Particle Size Distribution. Advanced Materials 2003,15,1844-1849. 

M. A. Hines, G.D.S., Colloidal PbS nanocrystals with size-tunable near-infrared emission Observation of post-synthesis self-narrowing of the particle size distribution. Advanced Materials, 15(21), 1844-1849 (2003). 

Conversely, in the summer, it would still have a high transparency for the visible, but a high reflectivity for the near infrared and a high emissivity for the far infrared. The present state of the art of thin-films deposition still falls short of this goal which may have to wait for the development of suitable photochromic coating materials. 

Most of the solid-state lasers employ as active material crystals or glasses doped with rare-earth or actinide ions, because these ions exhibit a large number of relatively sharp fluorescent lines, covering the whole visible and near-infrared spectrum 380) search for new laser materials and investigations of the characteristics of laser emission at different temperatures of the active material and with various pump sources have improved knowledge about the solid state spectra and radiationless transitions in laser media 38i). 

Many different types of photocathodes are used in photomultipliers. With a selection of various cathodes, it is possible to cover the range of response from the soft x-ray region (approximately 5 to 500 A) to the near infrared (approximately 12,000 A). Materials and combinations used include cesium-oxygen-silver cesium-antimony cesium-antimony-bismuth sodium-potassium antimony sodium-potassinm-cesinm-antimony copper-iodine and cesium-iodine. The thermal emission at 25°C of copper iodide and cesium iodide tends to run less than the other materials. 

Nanocrystals of Si trapped in some matrix form an attractive system for device fabrication when compared with Jt-Si, because of the increased surface stability and material rigidity. Visible EL has been observed, for example, from Si nanocrystals embedded in films of a-Si H78 and from an electrochemically-formed nanocrystalline Si thin film deposited on SnCL.79 In the latter case the p-i-n LED at room temperature emitted orange-red light (1.8 eV) that was readily visible to the eye. The light emission is ascribed variously to near surface states78 and the quantum size effect.79 Also, infrared emission near 1.1 eV has been obtained from a room-temperature EL device comprised of Si nanocrystals embedded within a Si-rich Si02-x matrix.80 The PL from this structure has an external quantum efficiency of 10 3. Substantial progress in the development of such nanocrystalline-Si EL structures can be expected over the next few years. 

The first optical laser, the ruby laser, was built in 1960 by Theodore Maiman. Since that time lasers have had a profound impact on many areas of science and indeed on our everyday lives. The monochromaticity, coherence, high-intensity, and widely variable pulse-duration properties of lasers have led to dramatic improvements in optical measurements of all kinds and have proven especially valuable in spectroscopic studies in chemistry and physics. Because of their robustness and high power outputs, solid-state lasers are the workhorse devices in most of these applications, either as primary sources or, via nonlinear crystals or dye media, as frequency-shifted sources. In this experiment the 1064-mn near-infrared output from a solid-state Nd YAG laser will be frequency doubled to 532 nm to serve as a fast optical pump of a raby crystal. Ruby consists of a dilute solution of chromium 3 ions in a sapphire (AI2O3) lattice and is representative of many metal ion-doped solids that are useful as solid-state lasers, phosphors, and other luminescing materials. The radiative and nonradiative relaxation processes in such systems are important in determining their emission efficiencies, and these decay paths for the electronically excited Cr ion will be examined in this experiment. 

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