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497. PAIRS: Program for the Analysis of Infrared Spectra
(VAX Version)
by Sterling Tomellini, Graham M. Smith and Hugh B.
Woodruff, Merck Sharp & Dohme Research Laboratories,
Rahway, New Jersey 07065
PAIRS has undergone major changes and advancements
since first being released to the public through QCPE
(as QCPE 426) in 1981. Noteworthy advancements include
(1) modification of the program to allow "vapor" as a
sample state and generation of interpretation rules for
vapor-phase species and (2) the development of a
version of PAIRS capable of allowing the user to
determine quickly how the expectation value for a given
functionality has been determined. This version of
PAIRS for the VAX contains these changes.
Other relatively minor changes were necessary to make
PAIRS compatible with the VAX 11/780. These changes
are basically user transparent, thus minimizing the
inconvenience caused on switching to the new version.
All capabilities of the IBM version have been
duplicated for the VAX version, with the exception that
a final report is not automatically printed.
PAIRS was designed to interpret IR spectra of
condensed-phase species (liquids and solids); but it
was realized that the usefulness of the program could
be further enhanced if IR spectra of vapor-phase
species could also be interpreted. Major changes were
made to both the interpreter and the rule compiler to
allow "vapor" to be included as a sample state.
Interpretation rules were developed based on Welti's
book Infrared Vapour Spectra (Heyden: New York, 1970)
for such functionalities as alcohols, phenols, amines,
amides, acids, esters and ketones. The new rules were
incorporated in such a way as to ensure the
uncompromised nature of the previously developed (and
extensively tested) condensed-phase rules. These rules
are designed to allow the spectra of intermediate
molecular weight compounds taken at moderate
resolutions to be interpreted. This added capability
should be of particular interest to those scientists
employing techniques such as GC/FTIR, off-gas and head
space analysis. Furthermore, the program changes now
make it possible for other users to develop
interpretation rules for vapor-phase species to meet
their particular needs.
The intent when developing PAIRS was to create a
program which would give a numerical indication of the
presence or absence of a given functionality based on
spectral information and a set of interpretation rules.
Every effort was made to make the interpretation rules
accessible and understandable, thus the rules were
written in the English-like language CONCISE. Manually
tracing the decision-making process can, however, be a
difficult and tedious task which essentially limits the
user to relying on the numerical indications presented
without further elaboration. In order to make PAIRS
more responsive to the needs of the practicing research
scientist, the program has been modified to allow the
decision-making process to be traced quickly in an
automated manner.
Allowing the decision-making process for a given
functionality or all functionalities advances the
program from being primarily an interpretation tool to
being an information resource as well. This added
capability should also greatly aid in the development
of interpretation rules by allowing the quick
evaluation of newly created rules.
FORTRAN 77 (VAX)
Lines of Code: 21,000
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