CO ladder
(CO rotational ladder, CO J ladder)
(series of CO rotational spectral lines)
The CO ladder (aka CO rotational ladder or CO J ladder)
is a carbon monoxide (CO) series of rotational spectral lines,
i.e., stemming from the steps in CO's possible rotational energy
(CO transitions), modeled by:
J(J+1)ℏ²
Erot = ————————
2I
where Erot is the energy level,
I is the moment of inertia of a CO molecule, ℏ
is the reduced Planck constant,
and J is 0, 1, 2, etc.
The frequencies of lines produced by stepping up or down these
energy levels are multiples of an increment near 115 GHz. The lines
are typically identified by this form: CO(number-number), with the
two numbers indicating two successive values of J.
Lines of interest include:
CO(7-6) | 806.7 GHz | 0.37 mm |
CO(6-5) | 691.473 GHz | 0.43 mm |
CO(5-4) | 576.3 GHz | 0.52 mm |
CO(4-3) | 461.0 GHz | 0.65 mm |
CO(3-2) | 345.8 GHz | 0.87 mm |
CO(2-1) | 230.5 GHz | 1.3 mm |
CO(1-0) | 115.3 GHz | 2.6 mm |
13CO(1-0) | 110.2 GHz | 2.72 mm |
These can be detected in distant galaxies (e.g., z=1)
within the millimeter/submillimeter range (e.g.,
submillimeter galaxies),
and suggest gas clouds,
i.e., indicating starburst galaxies and possibly mergers.
CO lines, such CO(1-0) are useful for determining redshifts.
CO(6-5) is used for observing protoplanetary disks
and very distant (z>6) molecular clouds.
Observations of multiple such lines (yielding their spectral line energy distribution (SLED)),
can yield qualities of the gas, in particular, its
temperature.
(chemistry,line series)
Further reading:
https://en.wikipedia.org/wiki/Rotational_spectroscopy
https://dictionary.obspm.fr/index.php?formSearchTextfield=co+ladder&showAll=1
https://www.cv.nrao.edu/~sransom/web/Ch7.html
https://sci.tanta.edu.eg/files/Microwave%20spectroscopy%20BSc-Lect-2.pdf
http://www-astro.physics.ox.ac.uk/~garret/teaching/rad-proc-lec-7.pdf
http://ned.ipac.caltech.edu/level5/Sept17/Carilli/Carilli2.html
https://ned.ipac.caltech.edu/level5/Sept15/Casey/Casey8.html
https://ned.ipac.caltech.edu/level5/Sept10/Krumholz/Krumholz2.html
https://ui.adsabs.harvard.edu/abs/2001ApJ...547..792D/abstract
https://ui.adsabs.harvard.edu/abs/2015A%26A...576A.109Y/abstract
WaveL | Freq | Photon Energy | | |
261μm | 1150GHz | 4.8meV | begin | CO ladder |
2.7mm | 115GHz | 476μeV | end | CO ladder |
|
Referenced by pages:
carbon monoxide (CO)
COMAP
spectral line designation
Index