We also observe an increase in the cis abundance in Ar and Xe matrices when comparing to the gas-phase abundances. When CH3ONO is isolated in an Ar matrix with a deposition angle of α = 20°, we observe the cis and trans conformer abundances to be 63 ± 3% to 37 ± 1%, respectively, shown in the middle trace of Fig. . There is an ~11% increase in the cis-CH3ONO population in the freshly deposited Ar matrix compared to the gas-phase abundances. Lastly, integration of the ν3 transitions in the Xe matrix, shown at α = 20° in the bottom trace of Fig. , results in measured cis and trans abundances of 73 ± 3% to 27 ± 1%, respectively, corresponding to a ~30% increase in the cis-CH3ONO abundance in the Xe matrix compared to its gas-phase abundance. All cis and trans conformer abundances in each freshly deposited matrix and the gasphase conformer abundance are summarized in Table .