Dr. Christopher Lue
Research Associate
Office: Lab Science West 536
Phone: 870-972-3686
E-mail: clue@astate.edu

 

Ph.D. – Emory University, Atlanta GA

B.S.  -Washington and Lee University, Lexington VA.

Research – I am currently working in The Arkansas Center for Laser Application and Science under the direction of Dr. Scott Reeve and Dr. Susan Allen.  The primary focus of my research is to obtain high resolution spectra of the vibration overtones of many of the molecules found in an “explosive bouquet”.   By explosive bouquet, I mean all trace the molecules typically found alongside the actual explosive in an explosive device.  My research uses cavity ringdown laser absorption spectroscopy (CRLAS) to study these molecules.

CRLAS is a high sensitivity absorption spectroscopy technique, which fallows the standard Beer’s law for molecular absorption: A=e·b·c where A is the absorbance, e is the molar extinction coefficient (mol∙L^-1_­∙cm^-1),  b is the path length (cm), and c is the concentration of the sample (mol∙L^-1_­).  In contrast to a typical absorption spectroscopy measurement which has a path length of the size of the absorption cell, CRLAS uses a sample cell (cavity) enclosed on each end by a highly reflective mirror (typically reflectivity = 99.995%).  Because the light bounces back and forth numerous times before leaving the cavity, path lengths up to several km are possible for a sample cell 0.5 m in length.  The light leaving the cavity can be described by the following equation:

, where I(t) is the intensity of light exiting the cavity at time t, I₀ is the initial light entering the cavity, and τ is the ringdown time typically measured in µs.

 

Because of the long path length, one has the ability to study very week abortions which could not be studied using a typical UV/Vis spectrometer.  Examples of specific molecules I am interested in studying are toluene and nitro benzene.  The data collected here will help in the development of novel spectroscopic detection methods for these compounds.    
Specific Aims:

1. Construct a working CRLAS experiment:

     a. Scanmate Pro dye laser Microbiology.
     b. Standard 0.5 CRD cavity.
     c. Photo multiplier tube.
     d. Digital oscilloscope/computer.

2. Use CRLAS to study materials found in explosive bouquets.

3. Develop fluorescence experiments complimentary to CRLAS experiments.