Optical stimulation

OSEE Optically stimulated exoelectron emission [143] Light falling on a surface in a potential held produces electron emission Presence and nature of adsorbates... 

NIRMS = noble-gas-ion reflection mass spectrometry OSEE = optically stimulated exoelectron emission PES = photoelectron spectroscopy PhD = photoelectron diffraction SIMS = secondary ion mass spectroscopy UPS = ultraviolet photoelectron spectroscopy ... 

Optically stimulated luminescence Amount of light emitted when sample is illuminated with laser light Sediments and soil Textbox 24... 

Both the thermoluminescence and optically stimulated luminescence techniques are suitable for dating past heating events over a timespan ranging... 

OSL Acronym for optically stimulated luminescence. oven A furnace used at relatively low temperatures, overglaze Pigment applied to the surface of pottery after glazing. oxidation A type of chemical reactions in which an atom or atomic group combines with oxygen or one or more electrons are removed from it. oxide A substance composed by the chemical combination of oxygen with another element. 

Stimulated release from an electron from the trap to the collection band, followed by emissive recombination with an activator. This process is called thermoluminescence (electron release stimulated by heating) and optically stimulated luminescence (electron release stimulated by light) (Fig. 2.6d) Extrinsic luminescence, where after being excited, electrons of defect ions recombine with the ground state with luminescence emission (Fig. 2.6e) ... 

Optical dating techniques, including OSL, optically stimulated phosphorescence (OSP), and phototransferred thermoluminiscence (PTTL) are applied to the dating of anthropological remains such as teeth and bones [65]. 

A description of the emission and capture processes at a trap will be useful before discussing the various experimental methods. Figure 1 depicts the capture and emission processes that can occur at a center with electron energy ET. The subscripts n and p denote electron and hole transitions, and the superscripts t and differentiate between thermally and optically stimulated processes. It is assumed here that only thermal capture processes are occurring. 

Figure 9. This alkaline-based glaze with a managanese Splash-glaze decoration was assigned to INAA Group 1. This sherd was directly dated by Optically Stimulated Luminescence to 1230 +/- 330A.D. (OxL-1353) (17).

For metal, dielectric and semiconductor films fabrication, optical and silica glass are popular substrate materials because of their availability, cost-effectiveness, and inert character, i.e., they are stable in the required temperature range for common photonic, optoelectronic and photovoltaic applications, they do not chemically react with the prepared films, and the hard plane surface makes the formation of optically smooth thin films fairly easy. Generally, it is preferable to form films by a simple, low-temperature, inexpensive and environment friendly method. Sol-gel technique and thermal evaporation is found suitable for the preparation of film parts of efficient solar cells [1], emitters, transformers [2], detectors and modulators of light [3], as well as optically stimulated luminescence dosimeters [4]. Here, we present the experimental data on the resistance to high-power optical and ionizing irradiations of the undoped components of film compositions with nanociystais. 

It is also possible to perform optical stimulation, viz. by irradiation with light the energy of which is sufficient to excite the electron from the trap into the conduction band. In certain applications this photostimulation plays an important role (see Chapter 8). 

The stoted energy can be released by thermal or optical stimulation. In the case of thermal stimulation the irradiated phosphor is heated to a temperature at which the energy barrier AE can be overcome thermally. The trapped electron (or hole) can escape irom the trap and recombine with the trapped hole (or electron). In the case of radiative recombination, luminescence is observed which is called thermally stimulated luminescence (TSL) (compare Sect. 3.5). Under optical stimulation the energy of an incident photon is used to overcome AE. The luminescence due to optical stimulation is called photostimulated lumine.scence (PSL). The phenomenon of stimulated luminescence from storage phosphors has been known since 1663 (Boyle). Storage phosphors have found a wide range of applications, e.g. as infrared detectors and in the field of dosimetry [3J. 

Another X-ray storage phosphor is RbBr TI+. The luminescent center is the TP (6s ) ion which emits by a 6s6p - 6 transition (Sect. 3.3.7). The electron is trapped at a bromine vacancy, the hole is assumed to be trapped at a Tl ion. The storage state can, therefore, be characterized by F -f Tl . The PSL center consists of these two centers optical stimulation excites the F center, and the electron recombines with the hole on thallium yielding TP in the excited state [19]. The efficiency of the photostimulated luminescence of RbBr TI+ decreases above 230 K due to a thermal instability of one of the trapped charge carriers. 

BasSi04Br6 Eu " and Ba5Ge04Brs Eu " [20]. Addition of a small amount of niobium improves the storage capacity and changes the storage mechanism [21], Irradiated samples show the presence of Nb (EPR), which is absent before irradiation. This shows that Nb " on a silicon site acts as an electron trap. Upon optical stimulation the electron becomes available for recombination with the trapped hole, the nature of which is unknown. 

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