An Evaluation of Femtosecond/nanosecond Laser Induced Breakdown Spectroscopy (LIBS) for Measuring Total Particulate Emissions
Abstract
Laser Induced Breakdown Spectroscopy (LIBS) involves the dissociation of molecular species into their atomic constituents and the sequent emissions from the excited atoms. Using the LIBS signal from a sample, one can identify the atomic species and their relative concentrations. From this information and appropriate calibration curves, simple molecular species can be identified and their concentrations can be estimated. This program seeks to answer the critical question: is it feasible to develop a LIBS based technique that can be used to make a quantitative distinction between gaseous and total particulates in a multi-phase sample containing a common type atom? The approach is to investigate single and dual pulse, ns and femtosecond (fs) LIBS techniques as a way of measuring different carbon species in gaseous, aerosol, and solid phases. The program involves joint efforts between the University of Florida and the Air Force Research Laboratory (AFRL). The University of Florida investigated single, ns-LIBS and dual, ns/ns-LIBS and AFRL investigated single ns-LIBS used in conjunction with dual fs/ns-LIBS. The program was partly successful in that the ratio of the ns/ns-LIBS signal and the ns-LIBS signal could be used to determine the percentage of gaseous and total particulate carbon. This approach has promise but the sensitivity needs to be improved to become a practical technique. The fs/ns-LIBS technique was disappointing. Within the parameters studied, it could not be used to determine the percent gaseous to particulate carbon. The reason for this is not understood but is believed to be related to the plasma dynamics.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 07, 2009
- Accession Number
- ADA606800
Entities
People
- Mike Brown
- W. M. Roquemore
Organizations
- Air Force Research Laboratory