Trihydrogen Cation - Spectroscopy

Spectroscopy

The spectroscopy of H₃+ is challenging. Due to its lack of a permanent dipole moment, pure rotational spectroscopy of H₃+ is impossible. Ultraviolet light is too energetic and would dissociate the molecule. Rovibronic spectroscopy provides the ability to observe H₃+. Rovibronic spectroscopy is possible with H₃+ because one of the vibrational modes of H₃+, the ν₂ asymmetric bend mode, has a weak dipole moment. Since Oka's initial spectrum, over 900 absorption lines have been detected in the infrared region. H₃+ emission lines have also been found by observing the atmospheres of the Jovian planets. H₃+ emission lines are found by observing molecular hydrogen and finding a line that cannot be attributed to molecular hydrogen.