FOR IMMEDIATE RELEASE:                       Fred McGehan
March 28, 1994                               (303) 497-3246

                                             TN-5972


             IMPROVED INFRARED CHEMICAL ANALYSIS POSSIBLE WITH
                            NEW NIST INVENTION

     A new device and technique recently patented by a National
Institute of Standards and Technology scientist may lead to
dramatic improvements in infrared spectroscopy, a process used to
identify and quantify the components making up a chemical sample.

     The improved analysis technique is possible because of a
NIST-designed sample-holding cell that provides a simple,
efficient and cost-effective means of cooling samples (to
temperatures as low as minus 40 degrees Celsius or minus
40 degrees Fahrenheit) during the measurement of their infrared
radiation absorption spectra.  The patent (no. 5,280,177) was
issued to Thomas J. Bruno, a physical chemist and group leader
in NIST's Thermophysics Division in the Chemical Science and
Technology Laboratory in Boulder, Colo.

     Cooling of a chemical sample during measurement of its IR
spectrum is important for two reasons.  During the procedure, the
sample is unavoidably heated by the radiation.  This can cause
the evaporation of solvents and chemical samples in the cell,
yielding inaccurate readings.  Moreover, many samples are
thermally sensitive and may be degraded by the heat.

     Conventional chilled sample cells use a small cryogenic
fluid container placed above the cell, the cooling of which is
counterbalanced by heaters mounted on the sides of the cell.
This design suffers from a number of drawbacks.  Unfavorable
temperature gradients are produced within the sample, and heating
that occurs through the primary (or "entry") window (through
which the IR radiation enters the sample cell) is always present.
The cryogenic container requires frequent filling with fluid to
maintain a constant cooling.

     The new cell features a sample chamber that is chilled with
the cold air stream produced from a vortex tube.  This gives it
the advantage of chilling the entire surface of the entry window
with the cold air, thus minimizing the heating from the IR beam. 
It is much smaller than the conventional chilled IR sample cell,
is easier to use and will fit any spectrophotometer.

       Bruno estimates that the complete cell could be produced
for about $300, significantly less than the approximately $6,000
price tag for a conventional chilled IR cell.

     For technical information about the new invention,
contact Bruno at Div. 838.01, NIST, Boulder, Colo. 80303-3328,
(303) 497-5158, e-mail: bruno@bldrdoc.gov (via Internet).  For
licensing information, contact Nancy Hale, B256 Physics Building,
NIST, Gaithersburg, Md. 20899-0001, (301) 975-4188.

     As a non-regulatory agency of the Commerce Department's
Technology Administration, NIST promotes U.S. economic growth by
working with industry to develop and apply technology,
measurements and standards.

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