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    • The benefits of gigahertz mode spacing for frequency comb applications
      The benefits of gigahertz mode spacing for frequency comb applications Dr Albrecht Bartels, managing director of Laser Quantum Recorded: May 30 2017 2:00 pm UTC 61 mins
    • After the first demonstration of an optical frequency comb based on a mode-locked laser in 1999, Ti:sapphire lasers with repetition rates around 1 GHz were the sources of choice for scientists around the world. Their key feature was a mode spacing 10 times higher than that of comparable 100 MHz sources (simplifying mode identification) and the ability to generate a fully coherent super-continuum with 100 times more power per mode either directly from the cavity or using an external microstructured fibre (enhancing signal-to-noise ratio). The world’s first optical atomic clock was built in 2001 using a 1 GHz Ti:sapphire laser and subsequently it has been shown that these lasers indeed support an accuracy at the 10–20 level with a 1 s stability at the 10–17 level and optical linewidths at the millihertz level, i.e. ideal candidate clockworks for a new generation of optical atomic clocks. The Ti:sapphire technology has even been taken out to as far as 10 GHz, a regime where individual modes with powers in excess of 1 mW can be separated with a grating spectrometer and used individually for direct spectroscopy, spectrograph calibration or optical arbitrary waveform generation.

      To overcome some of the disadvantages of early Ti:sapphire lasers (requirement for frequent alignment, cleaning and use of AO modulators for control purposes) and to make the full advantages of GHz frequency comb technology accessible to the science community, Laser Quantum has developed the hermetically sealed and permanently aligned taccor 1 GHz Ti:sapphire laser featuring an integrated pump laser with direct pump power control. This intervention free laser forms the basis for the new taccor comb system featuring an f-2f interferometer and full comb-stabilization electronics.

      This webinar reviews the benefits of gigahertz Ti:sapphire frequency combs and focuses on the recent progress using Laser Quantum‘s hermetically sealed line of taccor lasers.

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    • Low dimensional semiconductor nanostructures for solar energy conversion
      Low dimensional semiconductor nanostructures for solar energy conversion Masaru Kuno, Associate Professor, Dept. of Chemistry and Biochemistry, University of Notre Dame Recorded: Aug 25 2015 3:00 pm UTC 53 mins
    • Semiconductor nanostructures possess a number of applications in solar energy conversion. This includes using colloidal quantum dots in solar cells and, more recently, using analogous nanostructures such as nanowires (NWs) and nanosheets (NSs) in photocatalytic applications. In this presentation, we describe recent work to understand the photocatalytic response of solution-synthesized CdSe NWs and CdS NSs within the context of hydrogen generation. Various CdSe NW- and CdS NS-based systems such as core/shell structures and hybrid metal nanoparticle/semiconductor hybrid systems have been studied. In all cases, femtosecond transient differential absorption spectroscopy has been used to reveal relevant carrier relaxation processes in these materials as well as the flow of charges across the different heterointerfaces that are present. By correlating these transient absorption kinetics to results from accompanying hydrogen generation quantum yield measurements, we have, in turn, rationalized the response of these materials, clarifying the role that different heterojunctions play in establishing both charge separation and hydrogen generation efficiencies.

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    • Advanced sensors and smart control systems for coal-fired power plants
      Advanced sensors and smart control systems for coal-fired power plants Toby Lockwood Recorded: May 13 2015 11:00 am UTC 26 mins
    • Coal power plant control systems have progressively evolved to meet the growing demand for efficient and flexible power generation whilst maintaining low emissions. In particular, optimisation of the combustion process has required increased use of online monitoring technologies and the replacement of standard control loops with more advanced algorithms
      capable of handling multivariable systems. Improved stoichiometric control can be achieved with
      coal and air flow sensors or imaging and spectral analysis of the flame itself, whilst in-situ laser absorption spectroscopy provides a means of mapping CO and O2 distribution in hot regions of the furnace. Modern plant control systems are able to draw on a range of computational
      techniques to determine the appropriate control response, including artificial intelligence which
      mimics the actions of expert operators and complex empirical models built from operational data.
      New sensor technologies are also being researched to further improve control and to withstand the high temperature and corrosive environments of advanced coal plant and gasifiers. Increased use of optical technologies is of particular interest, with sensors based on optical fibres able to perform low noise, highly sensitive, and distributed measurements at high temperatures.
      Microelectronic fabrication techniques and newly developed high temperature materials are also being combined to develop miniaturised devices which provide a robust and low cost solution for in-situ monitoring of gases and other parameters. These new sensors can be integrated with wireless communication technology and self-powering systems to facilitate the deployment of distributed sensor networks and monitoring of inaccessible locations. Using principles of self-organisation to optimise their output, such networks may play a growing role in future control systems.

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    • NIR Calibration Transfer
      NIR Calibration Transfer Dr. Ron Rubinovitz Recorded: Aug 13 2009 5:30 pm UTC 30 mins
    • Near-infrared (NIR) spectroscopy offers users the capability to make rapid ID or quantitative measurements for a multitude of applications. Additionally, an essential feature for NIR use is the ability to transfer successful calibrations to other NIR spectrophotometers. Many manufacturers who use NIR for raw material identification and/or quantification of components in materials have the need to utilize multiple NIR spectrophotometers throughout their facilities. In these cases, it is essential to be able to develop calibrations using spectra generated on one NIR spectrophotometer and then transfer the calibrations to other NIR spectrophotometers at different locations. Another situation necessitating efficient calibration transfer occurs when manufacturers may need to replace outdated NIR spectrophotometers but still want to minimize time and resources by adapting the functioning calibrations that are in use. Such transfers allow users to reproduce existing NIR methods or replace older hardware platforms with minimal effort. In achieving transfer, there must be consideration for the type of instrumentation involved in the transfer, software tools available, calibration development, mathematical transformations, and model optimization.
      In this presentation, specific examples of calibrations transferred to Buchi spectrometers will be used to present a methodology for effective NIR calibration transfer across either identical or different vendor hardware platforms.

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    • Dietary supplement ID testing implementation
      Dietary supplement ID testing implementation Dr. Ron Rubinovitz Recorded: Mar 9 2011 6:30 pm UTC 31 mins
    • Many dietary supplement companies are turning to near-IR (NIR) as a means of performing rapid and unambiguous ID testing to be in compliance with current regulations. Although NIR is established in the pharmaceutical industry for this purpose, its application in the dietary supplement industry has special challenges. In particular, usually hundreds of raw materials need to be identified and individual materials may possess significant lot to lot variation and yet be similar in composition to other materials. This presentation will cover proven successful strategies that have enabled optimal efficiency in the implementation of NIR, dealing with specific steps such as installation, method development, validation, and routine analysis.

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    • Sports Drug Testing: Chromatography & Mass Spec-Based Approaches
      Sports Drug Testing: Chromatography & Mass Spec-Based Approaches Professor Mario Thevis Recorded: Sep 9 2010 3:00 pm UTC 51 mins
    • Doping control analysis predominantly utilises chromatography and mass spectrometry-based approaches to detect prohibited substances and methods of doping. These compounds and methods present both low and high molecular weight analytes of xenobiotic or natural / endogenous origin, which are to be detected, and occasionally quantified, using state-of-the-art instruments.

      The majority of the employed tools provides low resolving power. However, high resolution / high accuracy mass spectrometry has gained much attention recently due to: constantly increasing analytical requirements concerning the number of target compounds; the complexity of analytes (e.g. peptides and proteins); and the desire to accelerate analyses and obtain information (allowing for retrospective data mining).

      A selection of compounds, new challenges, and methods currently employed in doping control laboratories will be presented to the audience including, for example: new anabolic agents referred to as selective androgen receptor modulators (SARMs); insulins; so-called "releasing peptides" that stimulate the endogenous production of natural hormones; and ways of manipulating drug tests.

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