The Analysis of Coal with the Laser Mass Spectrometer

Abstract

The laser mass spectrometer has been used to pyrolyze petrographic constituents of coal and record the mass spectrum of the pyrolysis products thus produced. The laser mass spectrometer has been described in detail elsewhere. ^(1,2) Essentially, it consists of a small, pulsed ruby laser (max. output energy 0.1 J) whose output can be focused on the surface of a coal target located in the ionization chamber of a time-of-flight (TOF) mass spectrometer. A modified microscope optical system is used to focus the laser; irradiated targets can be as small as 10 μm in diameter. Since the target to be irradiated can be viewed through the same microscope system, selected petrographic areas of the coal sample can be pyrolyzed in situ. The spectra of these pyrolysis products can be used to study the chemical composition and structure of coal, or, even more simply, can be used as “fingerprints” to differentiate between the various heterogeneous constituents of coal.

The authors would like to express their appreciation to Dr. F. T. Ting for supplying several of the coal samples and making the reflectance measurements. The work was supported by a grant from the National Science Foundation.