Solids analysis using energetic ion bombardment and multiphoton resonance ionization

Due to its surface sensitivity and mass selectivity, secondary ion mass spectrometry (SIMS) has become a popular tool for the characterization of solids and surfaces. However, because of the useful ion yield (number of secondary ions detected/number of particles ejected) is typically less than 10-3, and since quantitative analysis by SIMS is hampered by severe matrix effects, the technique has not realized its full potential. It is the intent of this thesis to demonstrate that the sensitivity of the ion-bombardment experiment can be enhanced by selectively and efficiently detecting sputtered neutrals by the use of laser enhanced multiphoton resonance ionization (MPRI). With the appropriate experimental geometry, a high percentage of the sputtered atoms can be photoionized. Since the ionization is selective, the photoionized neutrals can be detected by a low resolution time-of-flight detector with high efficiency. By monitoring the ejected neutrals, matrix effects are greatly reduced. In this thesis, the design and operating characteristics of a spectrometer for performing MPRI of sputtered neutrals are described. Experimental parameters that effect the sensitivity of MPRI of sputtered neutrals are discussed in detail. Calculations indicate that sup-ppb determinations of many elements should be feasible