Jkg. Watson, Assignment of the lambda 1369.13 diffuse interstellar absorption band and three other far-ultraviolet interstellar absorption lines to the CH molecule, ASTROPHYS J, 555(1), 2001, pp. 472-476
The three unidentified interstellar lines lambda lambda 1368.74, 1369.13, a
nd 1370.87 are here assigned to the CH molecule, including the diffuse inte
rstellar band (DIB) at 1369.13 Angstrom. A consistent rotational assignment
of the interstellar lines and the 3d-X (2)Pi laboratory spectrum is presen
ted. The predominant broadening mechanism of the lines appears to be predis
sociation, which is found to be greater for lines with upper levels of d pa
rity, including the DIB, than for lines with upper levels of c parity. The
oscillator strength of the 3d-X (2)Pi transition is estimated to be f appro
ximate to 0.033. Using the theoretical n* dependence of the parameters toge
ther with the wavenumber of the observed laboratory Q-form branch, an unide
ntified interstellar line at 1270.96 is assigned to the strongest line of t
he 4d-X (2)Pi transition of CH.