SURFACE-ANALYSIS BY PHOTOIONIZATION OF SPUTTERED SPECIES WITH INTENSE PICOSECOND LASER-RADIATION

Intense ps laser radiation is used to photoionize sputtered atoms and molecules approximately 1 mm above solid surfaces by nonresonant multiphoton ionization (NRMPI), followed by time-of-flight mass spectrometry. At intensities approximately 1 x 10(14) W/cm2 even red light at 650 nm can completely photoionize (saturate) elements having a high ionization potential (IP), such as atomic O and Ar, as well as elements of lower ionization potential. The ability to efficiently ionize all these elements translates into uniform and high detection sensitivities, and the ability to quantify elements over a great range of ionization potentials.