excitation characteristics are canceled by using the ratio of the
two intensities. The outer gas flow rate to the ICP was 14 L/min;
the total amount of noble gas (He, Ne, Kr, and Xe) at any time is
only approximately 3% of total gas in ICP. All five pairs of gases
were used, namely, He-Ar, Ne-Ar, Ar-Ar, Kr-Ar, and Xe-Ar.
A shorthand notation, “XY”, is used to represent the gas flow
configuration, where X represents the chamber gas; and Y
represents the makeup gas, i.e., X is one of the five noble gases
and Y is Ar, or vice versa. For example, ArHe means that Ar is
chamber gas and He is makeup gas; HeAr means the reverse.