Research in Secondary Ion and Neutral Mass Spectrometry

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

In research supported by the Analytical and Surface Chemistry Program, Professor Emile Schweikert and his coworkers at Texas A&M University are developing new methods for mass spectrometry of surfaces.The research focuses on extracting more information from the ejecta generated when bombarding surfaces with keV mono and polyatomic projectiles. One objective is to achieve nanophase characterization via the detection of coincidentally emitted secondary ions. The approach relies on the novel concept of "mass separated time-of-flight mass spectrometry". A second objective is to advance detection sensitivity, which translates into the requirement of detecting neutrals. The approach is to collisionally cool the desorbed neutrals at ambient pressure, collect them into a supersonic molecular beam and subject them to efficient hyperthermal ionization for subsequent identification by time-of-flight mass spectrometry. In addition to enhanced detection sensitivity, the procedure should be useful for surfaces not readily amenable to examination in vacuum. This project deals with advancing chemical analysis expertise for examining surfaces. Progress in surface science and technology with emphasis on nanostructures requires the detection of vanishingly small amounts of molecules. The research aims to enhance our capabilities for identifying the chemical makeup of nanostructures and for detecting small numbers of molecules dispersed on a surface. The work will focus on two novel methods of mass spectrometry. One based on "mass-separated time-of-flight mass spectrometry" is expected to enable chemical analysis of nanodomains as small as ~ 30 nm. The other involves "ambient pressure secondary neutral mass spectrometry" with the goal of detecting molecules when they are randomly distributed on a surface (rather than assembled in a nanostructure) and when they are present in amounts which cannot be detected with current techniques.