Comment on "Experimental test of self-shielding in vacuum ultraviolet photodissociation of CO".

Chakraborty et al. (Reports, 5 September 2008, p. 1328) concluded that an anomalously enriched atomic oxygen reservoir can be generated through carbon monoxide photodissociation without self-shielding. We show that this conclusion is based on the incorrect assumption that the spectral shifts of the 97.03-nanometers and 107.61-nanometers vibrational bands for C16O, C17O, and C18O are negligible and point out shortcomings of the low-resolution light source used in their experiments.