NIST PIONEERS THE USE OF IMAGE PLATES FOR FAR UV SPECTROSCOPY.Researchers at NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. have demonstrated the effectiveness of photostimulable image plates for recording spectra in the far ultraviolet region of the electromagnetic spectrum electromagnetic spectrum Total range of frequencies or wavelengths of electromagnetic radiation. The spectrum ranges from waves of long wavelength (low frequency) to those of short wavelength (high frequency); it comprises, in order of increasing frequency (or decreasing . Although image plates have been used for higher energy applications such as x-ray crystallography X-ray crystallography, the study of crystal structures through X-ray diffraction techniques. When an X-ray beam bombards a crystalline lattice in a given orientation, the beam is scattered in a definite manner characterized by the atomic structure of the lattice. , no one previously had evaluated them for far UV spectroscopy. Based on the NIST results, image plates eventually may replace the expensive, hard-to-handle and often hard-to-obtain photographic plates traditionally used to record spectra at these wavelengths. Image plates are film-like sheets coated with a rare earth phosphor A rare earth material used to coat the inside face of a CRT. When struck by an electron beam, the phosphor emits a visible light for a few milliseconds. In color displays, red, green and blue phosphor dots are grouped as a cluster. See screen burn. such as BaFBrEu (barium fluorobromide doped with a trace of europium europium (y  rō`pēəm) [from Europe], metallic chemical element; symbol Eu; at. no. 63; at. wt. 151.96; m.p. about 820°C;; b.p. about 1,600°C;; sp. gr. 5. ). When an image plate is exposed to energetic radiation, electronhole traps are created in the phosphor that can persist for very long periods of time, even weeks. When illuminated with a red laser, the traps decay by fluorescing in the blue. If an image plate that has been exposed to high energy radiation is scanned with a laser in a special reader, a two-dimensional map of the exposed region is created in a computer. Software developed for this application then can be used to process the data. The image plate can be erased and reused. Furthermore, image plates have a response that is linear over a wide dynamic range. The NIST physicists successfully recorded spectra in the 5 nm to 60 nm region with the image plates, achieving sensitivity comparable to that of photographic emulsions made for this spectral region. These results were published earlier this year in Applied Optics Applied Optics is a peer-reviewed scientific journal published by the Optical Society of America three times a month. Founded in 1963. The journal has four divisions of editorial scope: optical technology; information processing; lasers, photonics and environmental optics; , Vol. 39, No. 4. |
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