Rotational Spectrum of CH+

The instrument called the Long Wavelength Spectrometer (LWS) in the Infrared Space Observatory detected emission lines associated with the pure rotational spectrum of CH+. The measurements show the rotational transitions characteristic of diatomic molecules. The rotational spectrum shows some centrifugal stretching as indicated by the calculated bond length in the table.

10-6m J+1->J R(nm)
179.62 2-1 .1146
119.90 3-2 .1147
90.03 4-3 .1148
72.140 5-4 .1149
60.247 6-5 .1150

For high rotational transitions, the molecule must be treated as a non-rigid rotor.

The spectral lines of CH+ reported above were observed in the planetary nebula NGC 7027. From relative intensities of the transitions a rotational temperature of 150 +/- 20 K was reported. A relative abundance CH+/CO of 2 to 6x10-4 was implied from the data.

Reference: "Discovery of Far-IR Pure Rotational Transitions of CH+ in NGC7027", Cernicharo, J., Liu, X.-W., Gonzalez-Alfonso, E., Cox, P., Barlow, M.J., Lim, T., Swinyard, B.M., Astrophysical Journal Letters v.483, p. L65, 1997.

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