An accurate and simple method of measuring relative mass spectrometric sensitivities

We describe an accurate and convenient method of determining the relative mass spectrometric sensitivities of various species by using surface decomposition reactions to generate these species in known stoichiometric ratios in situ in vacuum systems. In particular, we have used the decomposition reactions of formaldehyde and formic acid on Ru(001) to determine the relative mass spectrometric sensitivities of H_2, HD, D_2, and CO.