Breaking down buildings

Laura S. Marshall, laura.marshall@photonics.com

The composition of historic buildings can be analyzed using laser-induced breakdown spectroscopy (LIBS), report researchers from the University of Malaga.

A team from the laser laboratory in the university’s chemistry department, led by professor Javier Laserna, has tested LIBS in this capacity. Here, Laserna gives Photonics Spectra an exclusive look into the test. Other members of the laboratory who were involved in the study are Dr. Patricia Lucena, Dr. Xavi Moros, Dr. Fran Fortes and graduate students Inma Gaona, Salvador Guirado and Jorge Serrano.

Researchers are developing and testing a custom standoff LIBS system for use in analyzing the composition of buildings and more. Courtesy of professor Javier Laserna, University of Malaga.

Q: What was the aim of the study? What buildings did you analyze?

A: To analyze and determine the composition of the materials used for construction of the Cathedral of Malaga, built in the 18th century. We also aimed at investigating the pollution on the surface of these materials.

Q: What technology and methods did you employ for this project? Did you develop your own LIBS-based technology/methods or did you use standard components/instruments?

A: We used standoff laser-induced breakdown spectroscopy. With this technology, objects are inspected from a distance of up to 100 m. The instrument was designed and developed at University of Malaga using components from several manufacturers. Companies supplying the components were Andor Technology, Quantel Laser Systems and Optical Guidance Systems, among others.

Q: What were the results of your analysis?

A: Still processing. We discovered that the chemical composition of marbles differed in several areas of the main facade of the cathedral. These results are relevant for restoration and cleaning of the monument, as the cleaning procedures have to be adapted to the nature and composition of the materials. We also observed significant amounts of iron and manganese on the materials’ surface. These results seem to reveal the sources of contamination of these assets.

Q: What is the next step?

A: We have offered this technology to restoration units from other historical buildings. Also, standoff LIBS is available for inspecting other assets such as sculptures, frescoes, ornaments and construction details in building interiors. It should be noted that the technology does not require installing scaffoldings or other structures to facilitate system operation. Our campaign at the cathedral required only one day of work.