Near-infrared photons

The oxide CeC>2 doped with approximately 1% Er3+ exhibits up-conversion involving only one active ion. The Er3+ ions substitute for Ce4+ to form a low concentration of Erte defects randomly distributed within the oxide matrix. Irradiation with near-infrared photons with a wavelength of 785 nm excites the Er3+ ions from the 4Ii5/2 ground state to the 4I9/2 level, that is, a GSA mechanism ... 

W. Wang, B.H. Gu, L. Y. Liang, and W.A. HamUton Fabrication of near-infrared Photonic Crystals Using Highly-Monodispersed Submicrometer Si02 Spheres. J. Phys. Chem. B 107, 12113 (2003). 

Straub M, GuM (2002) Near-infrared photonic crystals with higher-order bandgaps generated by two-photon photopolymerization. Opt Lett 27 1824-1826... 

Reese, C., and Asher, S., Emulsifier-free emulsion polymerization produces highly charged, monodisperse particles for near infrared photonic crystals, J. Colloid. Interf. ScL, 248, 41, 2002. 

A.J. Miller, S.W. Nam, J.M. Martinis, Demonstration of a low-noise near-infrared photon counter with multiphoton discrimination, Appl. Phys. Lett. 83, 791-793 (2003)... 

F. MarteUi, Review An ABC of Near Infrared Photon Migration in Tissues The Diffusive Regime of Propagation,. Near Infrared Spectros., 20,29 (2012). 

In two photon polymerization (2PP) process, an initiator absorbs two near infrared photons simultaneously with a long wavelength through nonlinear absorption [103]. The nonlinear nature of two photon absorption process confines the photopolymerization to the focal volume (Scheme 8.2). 

C. Near-infrared photon detectors (semiconductors such as InGaAs, PbS, and InAs)... 

As it is well known, calculations on the solar spectrum impinging on the Earth surface demonstrate that the ideal photosensitizer for a system that would absorb the maximum fraction of energy (somewhat above 1000 nm) would absorb near infrared photons, and of course, all of the photons above that limit. Thus, new sensitizers are continuously prepared with a maximum in the NIR for the use in solar cells. However, organic light absorbers have relatively narrow bandwidths separated by deep minima, which makes it difficult to obtain panchromatic absorption in a single organic semiconductor. 

Another method, called photobleaching, works on robust soHds but may cause photodecomposition in many materials. The simplest solution to the fluorescence problem is excitation in the near infrared (750 nm—1.06 pm), where the energy of the incident photons is lower than the electronic transitions of most organic materials, so fluorescence caimot occur. The Raman signal can then be observed more easily. The elimination of fluorescence background more than compensates for the reduction in scattering efficiency in the near infrared. Only in the case of transition-metal compounds, which can fluoresce in the near infrared, is excitation in the midvisible likely to produce superior results in practical samples (17). 

Figure 7.3 shows the two-beam photon-force measurement system using a coaxial illumination photon force measurement system. Two microparticles dispersed in a liquid are optically trapped by two focused near-infrared beams ( 1 pm spot size) of a CW Nd YAG laser under an optical microscope (1064 nm, 1.2 MWcm , lOOX oil-immersion objective, NA = 1.4). The particles are positioned sufficiently far from the surface of a glass slide in order to neglect the interaction between the particles and the substrate. Green and red beams from a green LD laser (532 nm, 21 kWcm ) and a He-Ne laser (632.8 nm, 21 kW cm ) are introduced coaxially into the microscope and slightly focused onto each microparticle as an illumination light (the irradiated area was about 3 pm in diameter). The sizes of the illumination areas for the green and red beams are almost the same as the diameter of the microparticles (see Figure 7.4). The back scattered light from the surface of each microparticle is...

Matsuda, H., Fujimoto, Y, Ito, S., Nagasawa, Y, Miyasaka, H., Asahi, T. and Masuhara, H. (2006) Development of near-infrared 35 fs laser microscope and its application to the detection of three- and four-photon fluorescence of organic microcrystals. J. Phys. Chem. B, 110, 1091. 

Wenger OS, Giidel HU (2003) Influence of Crystal Field Parameters on Near-Infrared to Visible Photon Upconversion in Ti2+ andNi2+ Doped Halide Lattices 106 59-70 Wheatley AEH, see Linton DJ (2003) 105 67-139 Wilhelm M, see Haubner R (2002) 102 1-46... 

In addition to emitting electrons, a solid bombarded with ions in the keV range emits electromagnetic radiation from the near infrared to the near ultraviolet, with a photon yield of typically KT4 per incident ion for a metal, and 10 2 to 10 l for insulators. If the primary beam is intense, as in the dynamic SIMS range, and the sample is an insulator, one observes a bright glow at the point where the beam hits the sample. With conductors, the effect is not or hardly observable. 

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