1. General Description of the Tables
Two types of tables are presented for each molecular species. The first table
contains the derived molecular constants for each isotopic species which has
been studied. and the second table (accessed through an online form) contains
the observed microwave spectrum for all isotopic forms of the molecule.The
molecular spectral data tables of section 6 are
available with a table of the derived internuclear distances for all molecules
included in the review.
Literature references are labeled with a number from one of the two systems
employed here. In the first system. reference numbers range from 1 to
approximately 2000 and are identical to the bibliography compiled by Favero
[2]. The second system, which utilizes 5 digit
numerals, has been formulated such that the first two digits refer to the year
of publication of the reference work, while the remaining three digits
correspond to a chronological ordering within the year as required for
referencing purposes here. It is anticipated that this second technique, which
has more degrees of freedom, will be utilized entirely in the forthcoming parts
of this series on polyatomic molecules.
a. Molecular Constant Tables
Since a uniform format could not readily be constructed for these tables, they
were composed in variable format depending on the type of data available. In
general, the rotational constants are listed first, followed by hyperfine
structure data, electric dipole moments, rotational g-factors and
finally, the molecular reduced mass which was utilized in many isotopic
substitution calculations.
b. Spectral Line Tables
The spectral tables contain all of the data intrinsic to an assigned molecular
transition. The first column of these tables contain the isotopic molecular
species to which the data pertain. Each isotopic species is followed by the
assigned quantum numbers in the sequence: rotational, hyperfine, and
vibrational. The next columns contain the observed transition frequency, its
estimated uncertainty, parity when relevant, and finally the reference to the
original source of the data. In all cases the quantum numbers referring to a
particular transition frequency are listed with the upper energy state (primed
quantum numbers) first, followed by the lower energy state designation (double
primed quantum numbers). Since the vibrational state remains unchanged for all
transitions, a single quantum number, υ, is sufficient. In most cases the uncertainties and the
transition frequency measurements are reported directly from the original
reference. Since the number of significant figures beyond the decimal point was
fixed in this compilation, in a few cases it was necessary to round off the
measured data. This situation occurs primarily in the reproduction of molecular
beam measurements. Thus, when an uncertainty of ±0.01 MHz is quoted
in the spectral line tables, the uncertainty is often less than
±10 kHz, while a quoted uncertainty of ±0.00 MHz generally
means the uncertainty is less than ±1 kHz. When uncertainties in the
transition frequencies were not given in the original source, an uncertainty
was assigned on the basis of the internal consistency of all the data available
for the molecule in question. A hash mark (#) located in front of the uncertainty
denotes that the frequency is the hyperfine free center of the frequency.
A concerted effort was made to locate all of the essential references through
mid 1973. In situations where multiple measurements have been reported, the
sources not directly cited here are included as additional references at the
end of the molecular constant tables. In several instances this procedure was
not rigorously followed when the same transitions were reported in many
publications over a period of years with improved accuracy in each case. In
these cases only the more recent and most accurate citations are indicated.