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jcunha

Chemical analysis in Earth and Space via Raman Spectroscopy - 2 views

phys.org/...ical-analysis-earth-space.html

Raman chemical sensing BIO PHY space technology

shared by jcunha on 25 Sep 15 - No Cached
  • jcunha on 25 Sep 15
     
    "A new lightweight, energy-efficient tool for analyzing a material's chemical makeup could improve the detection abilities of various technologies, ranging from bomb-detecting drones to space rovers searching for signs of life". Raman Spectroscopy is about measuring vibrational modes in molecules. This vibrational modes are in the meV typically, turning Raman Spectroscopy into a high precision technique. This impressive work shows a new technique based on the use of optical fibers coupled to photomultipliers allowing its use, author's word, in extreme conditions such as unmanned aircraft vehicles (UAVs) and Mars/Moon rovers.
jaihobah

The Nanodevice Aiming to Replace the Field Effect Transistor - 2 views

www.technologyreview.com/...ce-the-field-effect-transistor

transistor PHY technology

shared by jaihobah on 03 Feb 16 - No Cached
LeopoldS liked it
  • LeopoldS on 08 Feb 16
     
    very nice! "For a start, the wires operate well as switches that by some measures compare well to field effect transistors. For example they allow a million times more current to flow when they are on compared with off when operating at a voltage of about 1.5 V. "[A light effect transistor] can replicate the basic switching function of the modern field effect transistor with competitive (and potentially improved) characteristics," say Marmon and co. But they wires also have entirely new capabilities. The device works as an optical amplifier and can also perform basic logic operations by using two or more laser beams rather than one. That's something a single field effect transistor cannot do."
  • ...1 more comment...
  • jcunha on 09 Feb 16
     
    The good thing about using CdSe NW (used here) is that they show a photon-to-current efficiency window around the visible wavelengths, therefore any visible light can in principle be used in this application to switch the transistor on/off. I don't agree with the moto "Nanowires are also simpler than field effect transistors and so they're potentially cheaper and easier to make." Yes, they are simple, yet for applications, fabricating devices with them consistently is very challenging (being the research effort not cheap at all..) and asks for improvements and breakthroughs in the fabrication process.
  • LeopoldS on 09 Feb 16
     
    any idea how the shine the light selectively to such small surfaces?
  • jcunha on 10 Feb 16
     
    "Illumination sources consisted of halogen light, 532.016, 441.6, and 325 nm lasers ported through a Horiba LabRAM HR800 confocal Raman system with an internal 632.8 nm laser. Due to limited probe spacing for electrical measurements, all illumination sources were focused through a 50x long working distance (LWD) objective lens (N.A. = 0.50), except 325 nm, which went through a 10x MPLAN objective lens (N.A. = 0.25)." Laser spot size calculated from optical diffraction formula 1.22*lambda/NA
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