Collaborative Research: RUI: Ion Mobility Spectrometry Radiative Ion-Ion Neutralization for Gas-Phase Ion Spectroscopy

Washington State University, Pullman WA

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Davis at Azusa Pacific University APU) and Professor Clowers at Washington State University (WSU) are pursuing a new approach for detecting and characterizing chemicals at trace levels using a technique termed Radiative Ion-Ion Neutralization (RIIN). Under the guidance of Drs. Davis and Clowers, a combined team of undergraduate and graduate researchers advance an innovative approach to chemical detection that has the potential to directly benefit a number of existing technologies routinely used for environmental monitoring, medical diagnostics, and threat detection in both the civilian and military domains. Current methods for detecting trace chemicals in the field often rely upon technology that not only ignores diagnostically-useful information, but restricts the chemical detection limits that may be reached. Successful characterization of the Radiative Ion-Ion Neutralization (RIIN) mechanism enhances the levels of information provided from rapid chemical measurements and impact fields from preliminary security screening to biochemistry. Through the implementation of this project, students from APU have the opportunity to travel to WSU during the summer academic months to work with Dr. Clowers and his students in a graduate-level research environment while students from WSU have the opportunity to travel to APU during the academic year to gain experience leading research and mentoring undergraduate research assistants. Existing approaches for ion detection at high pressure are inherently limited by the signal-to-noise performance characteristics of analog circuitry. At present, no compatible ion amplification technology is capable of single ion-counting under atmospheric conditions. This has constrained the growth and development of ion mobility spectrometry as a trace analytical tool. Radiative Ion-Ion Neutralization (RIIN) provides a new means of recording gas-phase ion signals that also integrates optical spectroscopy with traditional ion mobility measurements. The development and characterization of the RIIN detection platform is pursued across three objectives: 1) Development of RIIN as a quantitative gas-phase ion-transduction mechanism; 2) Determination of the RIIN photon release mechanism; and 3) Leveraging wavelength resolved RIIN signals for chemical identification. The unique signal transduction provided by the RIIN system directly benefits platforms focused on characterizing atmospheric pressure gas-phase ions and adds a highly informative second dimension of information that can more precisely assess the chemical content of complex mixtures. An equally important goal of this work is the integration of RIIN-informed gas-phase spectroscopy into the ion mobility experiment. The resulting multidimensional platform represents both a new analytical methodology and means of directly probing the chemical functional groups for gas-phase ions.