We have used a metastable argon beam to expose gold-coated silicon substrates covered with a self assembled monolayer (SAM) resist. The substrates have been covered with a patterned mask, with feamres of 10 pm size, and exposed to the atomic beam. Subsequent etching revealed negative contrast patterns, consistent with the formation of a negative contamination resist in the SAM, which we attribute to background pump oil vapour. Metastable dosages of 9x10L4a toms cnY2 and exposure times < 1 hr have been sufficient to produce reliable negative resists.