WAVELENGTH MODULATION SPECTROSCOPIC CHEMICAL SENSING USING A PIEZO-ELECTRIC TUNABLE FIBER BRAGG GRATING LASER Michael Buric, M.S. University of Pittsburgh, 2005 Real time gas sensing is paramount to numerous applications in industry as well as in the consumer sector. Many gas sensing applications such as fossil energy production require lowcost, multi-species sensors that are able to operate in...

introduction: this study investigated the influence of erbium-doped yttrium aluminum garnet (er:yag) laser on microhardness, chemical composition and subsurface morphology of dentin cavity walls. methods: forty sound human premolars were selected and randomly assigned into four groups. class v cavities were prepared either with an er:yag laser (groups 1 and 2; 15 hz, 250 mj for enamel, 10 hz, 2...

With new laser techniques and with gas phase and molecular beam experiments, it is now possible to determine the ultrafast motion in isolated chemical reactions-chemistry on the I 0 l 3 -second time scale. A decade ago this magazine devoted a special issue to laser chemistry (see PHYSICS TODAY, November 1980). One of the articles emphasized the importance of time scales in chemical reactions an...

low-power lasers are a group of lasers with a power less than 500 mw and unlike high-power lasers they have no effect on tissue temperature; they produce light-dependent chemical reactions in tissues. the purpose of this study was to review the clinical applications of these lasers and their success rate in different studies in orofacial pains. the articles with the key word “low level laser th...

introduction: the ultimate goal of endodontic treatment is to eliminate the bacterial infection in the root canal system. while mechanical debridement combined with chemical irrigation removes the bulk of microorganisms, residual bacteria are readily detectable in approximately one-half of teeth just prior to obturation. laser light can be used to destroy bacteria. this in vitro study was perfo...

This paper demonstrates, for the first time to our best knowledge, the application of a tunable external-cavity fiber Bragg grating diode laser in spectroscopic chemical sensing. A tunable fiber Bragg grating external-cavity semiconductor laser is demonstrated with over 10 nm of tuning range. A piezo-actuator was implemented to stretch the grating for rapid wavelength tuning of the laser. The a...

Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduc...

Electron motion in chemical bonds occurs on an attosecond timescale. This ultrafast motion can be driven by strong laser fields. Ultrashort asymmetric laser pulses are known to direct electrons to a certain direction. But do symmetric laser pulses destroy symmetry in breaking chemical bonds? Here we answer this question in the affirmative by employing a two-particle coincidence technique to inv...

We review laser applications in thin-film photovoltaics (thin-film Si, CdTe, and Cu(In,Ga)Se2 solar cells). Lasers are applied in this growing field to manufacture modules, to monitor Si deposition processes, and to characterize opto-electrical properties of thin films. Unlike traditional panels based on crystalline silicon wafers, the individual cells of a thin-film photovoltaic module can be ...