GHz units are normally used in the microwave region. For this region
it is also advised to use the VVW Flag
or Van Vleck Weisskopf lineshape in the *SHP
section.
Internally the RFM always works in cm-1,
so spectral ranges defined in
GHz in the *SPC section
are converted to cm-1 using the factor
1E7/VLIGHT (approximately 1/30),
where VLIGHT, the speed of light, is defined in
phycon_dat.f90.
Conversely, the spectral axis (defined in header record#3 of the
output spectral files),
is converted back to GHz before being
written to the file.
.ils files (more commonly known as
spectral response functions in the microwave)
may be expressed in either cm-1
or GHz. If incompatible with the GHZ Flag,
the appropriate conversion is made
and a warning message sent to the
rfm.log file
.tab input/output files may be specified
on GHz or cm-1 axes, the RFM handles the conversion automatically.
All other spectral input data, e.g., in the
*HIT,
*XSC and
*CIA sections,
are always assumed to be in cm-1.
