Abstract

A broad suite of laser-based techniques can be used to characterize and better understand changes in biological and environmental matrices, such as leaves, shoots, roots and soils. This talk will summarize the past decade of research using laser-induced breakdown spectroscopy (LIBS), a technique complementary to inductively coupled plasma mass spectrometry but elegantly simpler in sample preparation and more versatile for the analysis of inconvenient samples and matrices.  

ORNL has been at the forefront in the application of LIBS for the identification and quantification of elements present in biological and environmental samples. Recently, our group has used LIBS to advance the field of ionomics, the study of changes in inorganic element composition in response to physiological stimuli, developmental state, and genetic changes.

I will speak on advances in LIBS techniques at ORNL for determining the viability of switchgrass and poplar trees as biomass that can be used to produce high-quality biofuels, as well as the impacts of climate change such as how trees respond to wildfires started during droughts. This research complements the vision of the Center for Bioenergy Innovation at ORNL, which is to accelerate domestication of bioenergy-relevant plants and microbes for use in the development of high-impact, value-added products throughout the bioenergy supply chain. Use of LIBS also has led to these scientific discoveries:

• Determination of how much ash and inorganic material are present in 73 samples of switchgrass, which could indicate whether this plant’s biomass can be converted into renewable biofuels. 

• Characterization of poplar hardwood samples for difficult-to-measure elements such as silicon, potassium, calcium, magnesium, phosphorus and sulfur.  

• Identification of forest fire events by scanning fire-affected wood to detect changes in tree-related chemistry, a technique used to help solve a crime.

• Identification of weather events, such as wet, dry and ambient conditions at the simulated treatment plots at the throughfall displacement experimental site in Oak Ridge.

• The leveraging of ionomics with new genotyping technologies to rapidly identify genes that control the accumulation and distribution of elements in plants. This research is also crucial to understanding the complex regulation of the ionome, the inorganic elemental composition of a subcellular structure, cell, tissue, organ or organism.

• The use of hierarchical models to identify and quantify specific elements. 

These examples demonstrate how advances in LIBS-based techniques have enabled the determination of the viability of a variety of plant species as biomass suitable for production of biofuels and determination of climate change impacts. By incorporating LIBS in the biofuels life-cycle economy, the best possible biomass available for conversion into high-quality biofuels will be identified. In addition, fluctuations in elemental content that LIBS can detect in tree rings during different weather events will help us better understand impacts of climate change, helping scientists to develop strategies to deal with them.

Biographical Sketch

Dr. Madhavi Martin is a senior staff research scientist at Oak Ridge National Laboratory, where she is the leader of the Biomaterials and Biomass Characterization Group in the Biosciences Division. She is known for her use of laser-induced breakdown spectroscopy (LIBS) for determining the composition of and changes in biological and environmental samples, such as plant tissues, roots, tree rings, and soils.

A native of India who was encouraged by her father to study physics, she earned a bachelor’s degree in physics at the University of Nagpur in India, followed by a master’s degree in solid-state physics at Shivaji University. She then moved to the United States and earned a second master’s degree and a doctorate in solid-state physics from the University of California at Los Angeles. At UCLA she concentrated on spectroscopic methods for materials science and for the characterization of high-frequency semiconductor devices made of heterogeneous thin films.

After earning her Ph.D., Dr. Martin began working for the University of Tennessee at Knoxville in the school’s Measurement and Control Engineering Center. While there she established a Raman spectroscopy-based monitoring system at Eastman Chemical Company in Kingsport, Tenn., to evaluate the company’s distillation column for a key product. The monitoring system identified issues with the column in real time versus a method of weekly sampling, significantly reducing the company’s costs. Dr. Martin later joined ORNL as a postdoctoral researcher with a specialty in spectroscopy. She was hired as a staff scientist four years later.

Since 2004 she has been a member of the International Scientific Committee for the Laser-induced Breakdown Spectroscopy Society. In 2007 she was awarded a one-year Sir Frederick McMaster Fellowship by the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia to explore the development of rapid assessment tools for characterizing the chemical and mechanical properties of wood, wood products, and woody and herbaceous biomass for biofuels applications.