Abstract: | Compounds C6H5X(X ? F, Cl, Br, NO2, CN, OCH3) have been studied under chemical ionization conditions with ammonia as reagent gas. A pulsed electron beam and time resolved ion collection has allowed the determination of the reaction leading to the formation of [C6H5NH3]+ (m/z 94). [NH4]+ reacts with C6H5X(X ? F, Cl, Br) to yield m/z 94 but C6H5X (X ? CN, NO2) forms this ion only by reactions involving either [NH3]+ or [C6H5X]+. C6H5OCH3 does not form m/z 94. |