Rice air sensors tested near Beijing’s Olympic stadium

Rice air sensors tested near Beijing’s Olympic stadium
Laser-based devices measure ozone-precursor nitric oxide

BY JADE BOYD
Rice News staff

The Summer Olympics may be the hottest ticket in Beijing this summer, but researchers from Rice’s Laser Science Group with collaborators with Princeton University are conducting their own world-class event in the Chinese capital — a first-of-its-kind air-quality study involving new laser-based sensors designed and built by the Rice-Princeton team.

	COURTESY PHOTO
	Rice’s Frank Tittel is using sensors near the Olympic stadium in Beijing to continuously monitor atmospheric trace gases before, during and after the Summer Games.

Rice’s Frank Tittel, the J.S. Abercrombie Professor in Electrical and Computer Engineering, and Rafal Lewicki, a visiting graduate student, are using sensors near the Olympic stadium to continuously monitor atmospheric trace gases before, during and after the Summer Games. They are working with colleagues from the Chinese Academy of Sciences and Princeton University’s MIRTHE center, including Assistant Professor Gerard Wysocki, formerly a faculty fellow in electrical and computer engineering at Rice.

MIRTHE, short for Mid-InfraRed Technologies for Health and the Environment, was established in 2006 with a $15 million grant from the National Science Foundation. Rice is one of six core partner institutions in the Princeton-based center, which is led by professor Claire Gmachl.

“Our system can continuously make sensitive and selective measurements of nitric oxide, even in the presence of strongly interfering gases like water vapor and carbon dioxide,” Tittel said.

FRANK TITTEL

Nitric oxide, a molecule containing one atom of nitrogen and one atom of oxygen, is an ozone precursor that’s found in automobile exhaust. While scientists have had the tools to measure it in air samples for years, the machines needed to analyze the samples were usually large and expensive. Moreover, the process was slow, with samples being collected in the field, shipped to a laboratory and put through a time-consuming analysis.

“The continuous monitoring of nitric oxide that we’re doing has never been done before,” Tittel said. “If the technique proves robust, it will open the door for new types of real-time atmospheric monitoring.”

Tittel said Rice’s new sensors employ “quantum cascade” lasers, a unique type of laser invented in the mid-1980s. The lasers in the new sensors emit at a particular wavelength of mid-infrared light that is absorbed by nitric oxide. Using laser absorption spectroscopy, the sensors are able to measure nitric-oxide concentration at the parts-per-billion level.

Tittel said the team will collect data for nearly two months, and all the data must be thoroughly analyzed before any conclusions can be drawn about the technique or the concentration of pollutants in Beijing’s air. He said the group hopes to publish its findings as early as next summer.