Protonated formaldehyde (H2COH+) was identified in a 1996 paper by
Ohishi et al.. They found up to six lines in
sources including the star-forming regions Sgr B2(M),
W51 and tentative detections in
NGC 7538 and DR21(OH) using the
Nobeyama Radio Observatory and facilities at
Kitt Peak. Confirmation of the detection includes 2008 papers by
Requena-Torres et al. and
Jones et al..
The detection was based upon a laboratory spectrum by
Chomiak et al.
Later papers by Dore and co-workers provide additional spectroscopic data for
protonated formaldehyde as well as two of its