ED I T 0 R SI COLUMN
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LTHOUGH the field of laser technology is scarcely a decade old, many new developments in this area, with possible implications for analytical chemists, are currently being reported. I n this month's Report for Analytical Chemists, page 20 A, P. AI. Rentzepis and C. J. Mitschele of Bell Telephone Laboratories trace the development of the new field of picosecond laser spectroscopy and describe a number of applications of picosecond pulses of light of interest to chemists. Bell Laboratories, Eastman Kodak, and I B V have all been leaders in the evolution of the laser, and each of these companies has recently contributed new breakthroughs of considerable significance. Izuo Hayashi and Norton Panish of Bell Laboratories have devised a new semiconductor laser, smaller than a grain of sand, that can be powered by ordinary dry cell batteries. The new laser is a double heterostructure diode composed of four layers of gallium aluminum arsenide alternating with gallium arsenide. These layers are doped with tin, silicon, zinc, and germanium. T h e laser operates continuously a t normal room temperature (75-80°F), converting electrical current directly into coherent light. The emission wavelength of the laser occurs in the near-visible infrared region a t about 8500 k . Such lasers have potential for transmitting voice, data, and other information signals in high-capacity optical communications systems. According to Bell Labs, semiconductor lasers are also expected to have a significant impact upon the new technology of optical electronics. Bell Labs and Eastman Kodak have recently developed new lasers which utilize organic dyes as the lasing material. The Bell Labs version (ASAL. CHEM., October 1970, New Products, page 115 A) , devised by Anthony Trozzolo, Andrew
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You choose and pay for a Cryo-Tip' refrigerator on the basis of the temperature range. The AC-1 ranges from 300°K down to 68°K; the AC-2 and AC-2L down to 1 6 ° K ;the AC-3L to 3.6"K; and the LT-3 to Z'K. You don't have to buy a wider temperature range than you need. You don't get involved with specialty dewars and complex electrical controls, either. You simply meter the flow at the control panel and it stays within 0.1'K for either the economical cylinder gas Cryo-Tip refrigerators or the LT-3 Liquid Helium Transfer System. Each Cryo-Tip refrigerator can be
Circle NO. 9
fitted with a variety of vacuum shrouds for all applications. They're part of the complete line of accessories that adapt the Cryo-Tip system to low-temperature studies like these: 0 IR, UV, Visible, Nuclear, M o s s bauer and Raman Spectroscopy. 0 magnet studies like EPR, N M R , ESR. 0 field ion microscopy, X-ray diffraction, lasers. Call A1 Koury at (215) 395-8355 for information, or write to Advanced Products Dept., Air Products and Chemicals, Inc., P.O. Box 538, Allentown, Pa.
on Readers' Service Card
ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970
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he NMR system that produced all the spectra on this pa e costs less than $4 a
\ " N M R can bezlsedto
analyzepesticiakr and other phoq%orus-containing chemicals such as trimetby#&o-rphite (spectrumshown).
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'FNMR analysis is applicable to isomeric mixturessuch as shown in this spectram of ~,~,2-tr~uoro-2-chloro-3vinyhyclobutane, Peaks mrkedA are ofone ofthetwo isomers.
\ ACETYL ACETONE
'H NMR analysis of acetyjdcetoneat -IP°C, +4OoGand +IoO~Cshows the temperature dependence ofthis keto/enoZ eqaih8rium.
For details, or to arrange for a demonstration,write [ovarian, Analytical Instrument Division,611 Hansen Way, Palo Alto, California 94303 Circle No. 171 on Readers' Service Card
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ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970
Editors’ Column
Dienes, and Charles Shank, uses the dye molecules 4-methylumbelliferone and 7-hydroxycoumarin in the excited state to create a new form of the original dye. This form is called an excited-state complex, or “exciplex.” The new laser may be ‘.tuned” to emit light in a range of wavelengths 1760 A wide-from near ultraviolet to yellow. Tunability of this magnitude is reported t o be one of the most significant ads-ances since the introduction four years ago of organic dye molecules as lasing materials. The Eastman Kodak laser, developed by Otis Peterson, Sam Tuccio, and Benjamin Snavely, employs a water solution of an organic dye excited by an argon ion source t o produce a continuous yellow laser beam. With continuous operation proved feasible, it now becomes possible to exploit the low cost and tunable was-elength advantages of organic dyes over such other lasing materials as rubies, glasses, and gases in many applications. The variety of available dyes permits operation of dye lasers throughout the visible spectrum and the near-infrared and ultraviolet. The dye laser should be useful as a research tool, providing intense, tunable monochromatic radiation. Simplification and even mass production of inexpensive lasers may result from these advances. 44laser whose light has the shortest wavelength so far reported has been de~elopedby Rodney Hodgson of IBM’s Research Division. The new laser utilizes molecular hydrogen as the actire medium and emits light with a wavelength near 1600 A in the vacuum ultraviolet regioii-corresponding to a photon energy of almost 8 eV. The hydrogen laser has sufficient photon energy to break chemical bonds that are too strong to break by previously available laser energies, The I B l I device emits pulses about 2 nsec long, making it possible t o study the kinetics of many chemical reactions.
for Simultaneous Concentration or Evaporation ob Ten Samples in 10 to 20 Minutes
ROTARY EVAPO-MIX
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Our Infrared Accessories Catalog isfree, new and corn[
96 pages of text, pictures, diagrams and prices describe Perkin-Elmer’s comprehensive line of the finest quality infrared spectroscopy accessories. Includes macro and micro liquid, gas and solid sampling cells, sampling kits, gratings and crystal optics and many special items such as polarizers, internal reflectance units and calibration kits. For your copy write to Instrument Division, Perkin-Elmer Corp., 702 Main Avenue, Norwalk, ‘Onn.
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ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970
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