Optical Advances

The IR-PLAN was patented in 1989 [3] and designed as an attachment for any commercial FT-IR instrument. Subsequently, other manufacturers provided similar peripheral microscopes for the same purpose with, in each case, an optical 

The enhanced spatial resolution which is enabled by the substitution of synchrotron radiahon for a thermal (globar) source was a significant instrumental advance. 

The introduction of focal plane array (FPA) systems, initially InGaAs, for near-IR by Marcott and Lewis [4] occurred on 20 June 1994, while the subsequent development for mid-IR, using a mercury cadmium teUuride (MCT) array by Lewis and Levine [5] at Bethesda, Maryland, resulted in very rapid image generation. 

The instrument development cycle that began with a microscope accessory for an FT-IR spectrometer turned full circle with the production of a miniature interferometer accessory (the lUuminatIR ) for a research microscope. This latter development opened IMS to professional microscopists by adding a new, chemically selective dimension. Another small footprint-dedicated portable IMS used a diamond internal reflection element (IRE) to analyze solids or liquids on location. 

The internal reflection IMS is used in conjunction with a laptop computer that contains a spectral library this set-up enables emergency first responders or investigators to perform the onsite identification of unknown or potentially hazardous materials. 

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P. C. Schultz, in Fiber Optics Advances in Research and Development, B. Bendow, S. S. Mitra eds., lenum Press, New York, 1979. 

SYNTHETIC APPROACH FOR PREPARATION OF NANOMETER-SIZED NON-LINEAR OPTICAL ADVANCED MATERIALS... 

Vibrational spectroscopies (mid-IR, near-IR, Raman) play an important role in polymer/additive analysis. Optical advances as well as spectacular advances in computing technology and data processing algorithms have greatly impacted vibrational spectroscopy over the past 25 years (cfr Table 1.5). Rapid digital data acquisition is required for FTIR, FT-Raman or CCD-Raman spectroscopy. The raw data obtained from these instruments must always be manipulated before a recognisable spectrum can be displayed. 

The simultaneous measurement of several Raman bands and the general increase in measurement speed have, in practical terms, been important for artefact reduction, perhaps more so than optical advances because of their easier implementation. Taken together these two advances allow one to check and adjust the baseline before, and if need be, during a ROA measurement. 

Bates D R 1991 Negative ions struoture and speotra Advances in Atomic, Molecular and Optical Physics ed D R Bates and B Bederson (New York Aoademio)... 

A diagrannnatic approach that can unify the theory underlymg these many spectroscopies is presented. The most complete theoretical treatment is achieved by applying statistical quantum mechanics in the fonn of the time evolution of the light/matter density operator. (It is recoimnended that anyone interested in advanced study of this topic should familiarize themselves with density operator fonnalism [8, 9, 10, H and f2]. Most books on nonlinear optics [13,14, f5,16 and 17] and nonlinear optical spectroscopy [18,19] treat this in much detail.) Once the density operator is known at any time and position within a material, its matrix in the eigenstate basis set of the constituents (usually molecules) can be detennined. The ensemble averaged electrical polarization, P, is then obtained—tlie centrepiece of all spectroscopies based on the electric component of the EM field. 

Many of the fiindamental physical and chemical processes at surfaces and interfaces occur on extremely fast time scales. For example, atomic and molecular motions take place on time scales as short as 100 fs, while surface electronic states may have lifetimes as short as 10 fs. With the dramatic recent advances in laser tecluiology, however, such time scales have become increasingly accessible. Surface nonlinear optics provides an attractive approach to capture such events directly in the time domain. Some examples of application of the method include probing the dynamics of melting on the time scale of phonon vibrations [82], photoisomerization of molecules [88], molecular dynamics of adsorbates [89, 90], interfacial solvent dynamics [91], transient band-flattening in semiconductors [92] and laser-induced desorption [93]. A review article discussing such time-resolved studies in metals can be found in... 

Reider G A and Heinz T F 1995 Second-order nonlinear optical effects at surfaces and interfaces recent advances Photonio Probes of Surfaoes ed P Halevi (Amsterdam Elsevier) pp 413-78... 

Earle K, Budll D and Freed J 1996 Millimeter wave electron spin resonance using quasloptical techniques Advances in Magnetic and Optical Resonance vol 19, ed W Warren (San Diego ... 

Pohl D W 1991 Soanning near-field optioal miorosoopy (SNOM) Advances/n Optical and Electron Microscopy yo 12, ed R Barer and V E Cosslett (London Aoademio)... 

Bates D R and Bederson B (eds) 1989 Advances in Atomic Molecular and Optical Physics vol 26... 

Bederson B and Dalgarno A (eds) 1994 Advances in Atomic Molecular and Optical Physics vol 32 Bederson B and Walther FI (eds) 1994 Advances in Atomic Molecular and Optical Physics vol 33 Bederson B and Walther FI (eds) 1998 Advances in Atomic Molecular and Optical Physics vol 38 Scoles G (ed) 1988 Atomic and Molecular Beam Methods (New York Oxford University Press)... 

Our intention is to give a brief survey of advanced theoretical methods used to detennine the electronic and geometric stmcture of solids and surfaces. The electronic stmcture encompasses the energies and wavefunctions (and other properties derived from them) of the electronic states in solids, while the geometric stmcture refers to the equilibrium atomic positions. Quantities that can be derived from the electronic stmcture calculations include the electronic (electron energies, charge densities), vibrational (phonon spectra), stmctiiral (lattice constants, equilibrium stmctiires), mechanical (bulk moduli, elastic constants) and optical (absorption, transmission) properties of crystals. We will also report on teclmiques used to study solid surfaces, with particular examples drawn from chemisorption on transition metal surfaces. 

Early experiments witli MOT-trapped atoms were carried out by initially slowing an atomic beam to load tire trap [20, 21]. Later, a continuous uncooled source was used for tliat purjDose, suggesting tliat tire trap could be loaded witli tire slow atoms of a room-temperature vapour [22]. The next advance in tire development of magneto-optical trapping was tire introduction of tire vapour-cell magneto-optical trap (VCMOT). This variation captures cold atoms directly from the low-velocity edge of tire Maxwell-Boltzmann distribution always present in a cell... 

The study of organic semiconductors and conductors is highly iaterdisciplinary, involving the fields of chemistry, soHd-state physics, engineering, and biology. This article provides a treatment of the theoretical aspects of organic semiconductors as well as an overview of recent advances ia the field and the uses of these materials based on their conductive and optical properties. 

Mercury(II) fluoride has been used in the process for manufacture of fluoride glass (qv) for fiber optics (qv) appHcations (11) and in photochemical selective fluorination of organic substrates (12). It is available from Advance Research Chemicals, Aldrich Chemicals, Johnson/Matthey, Aesar, Cerac, Strem, and PCR in the United States. The 1993 annual consumption was less than 50 kg the price was 800—1000/kg. 

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