Abstract
In a recent paper by the authors (Ref. 1), it was claimed that NO2 2+ was observed for the first time via electron impact of NO2. The existence and the appearance potential of NO2 2+ has been reported earlier by Cooks, Terlwillinger, and Beynon (Ref. 2). The results of Ref. 2 are compared with the author’s measurements. (AIP)