Development of a hollow cathode ion source for the Cameca 3f secondary ion massspectrometer

As an alternative to the expense of a dedicated glow discharge mass spectrometer, a hollow cathode ion source has been developed for the Cameca IMS 3f secondary ion mass spectrometer. The hollow cathode is constructed easily from four pieces of conducting or semiconducting sample and extends applications of the secondary ion mass spectrometer for bulk analysis.;One of the problems encountered in glow discharge mass spectrometry is the occurrence of interferences due to cluster ions which have the same nominal masses as the analyte ions. To achieve low detection limits it is essential to reduce or eliminate the cluster ion inteferences. The energy distributions of the ions produced in a hollow cathode ion source were studied using a Cameca IMS 3f secondary ion mass spectrometer equipped with a glow discharge hollow cathode ion source. Aluminum standards containing various impurities at concentrations of a few hundred ppm were used in the study. Two prominent peaks were found in the energy distributions, corresponding to ions with the high kinetic energies (formed in the negative glow region of the discharge) and ions with low kinetic energies (formed at or near the extraction aperture in the base of the hollow cathode). For matrix Al;Unlike other techniques, atomic ion intensities were increased at the same time as the interferences were reduced due to the characteristic energy distribution of the atomic ions. For most of the impurity elements in the standards, the sensitivities increased from a few tens to a few hundreds of counts per ppma. The relative ion yields of the impurity elements obtained with high energy ions were within a factor of 3.