This is a collaborative project between an NSF Engineering Research Center for Technologies for Health and the Environment (MIRTHE) and Physical Sciences Inc. (PSI), a company that is a world-renowned leader in the research and development of laser chemical sensing technologies. The proposal focuses on developing a new, compact, cryogen-free mid-infrared hard-target LIDAR (laser detection and ranging) technology for remote spectroscopic chemical sensing that will target atmospheric methane. The proposed system will be based on a new chirped laser dispersion spectroscopy (CLaDS) technique, recently invented by the PI, who is a researcher at the MIRTHE ERC. The proposal will develop a new remote sensing technology that is capable of atmospheric CH4 monitoring and will provide significant improvements over the current state-of-the-art. Present concentration in North America range from 1600 to 2200 parts per billion by volume (ppbv). Unfortunately, it is difficult to fully quantify its emission rates and location of sources and sinks using existing methane monitoring instrumentation. Thus technologies that enable remote sensing of natural and anthropogenic methane emissions are needed for accurate source and sink assessments of this important greenhouse gas. The new sensor system, CLaDS, is based on measurement of resonant molecular dispersion and provides unique capabilities for remote chemical detection (i.e. immunity to optical power fluctuations). The proposed instrumentation will also take advantage of another core MIRTHE technology; quantum cascade lasers (QCLs). QCLs give an access to the mid-infrared region of electromagnetic spectrum between ~3 and 16 ìm where most chemical compounds in the gas phase (including methane) possess their strongest fundamental ro-vibrational absorption features. As a result, detection at mid-IR wavelengths enables ultra-high sensitivity detection of trace-gases.
Broader Impact
Ultra-sensitive, fast, in-situ molecular remote detection has a large number of applications in environmental studies, industrial emission monitoring and security. Therefore new discoveries and scientific advancements in this field integrated with a comprehensive educational program will provide an excellent training for the new generation of scientists and engineers as well as have a strong impact on the well being of society. The versatility of the project provides a full spectrum of education and training opportunities integrated with the research goals and specifically addresses career development goals at each academic level from high school students to post-doctoral researchers. Participation of a graduate student and a post-doc is planned within the budget of this project. The engagement of undergraduate students will be provided through other programs including a strong MIRTHE Research Experience for Undergraduate (REU) Program.
Remote sensing of methane (CH4) is of importance in a number of atmospheric monitoring applications. Recent studies showed that increase of the concentration of methane unexpectedly stopped in the 1990s. Present concentration in North America ranges from 1600 to 2200 ppbv. Unfortunately, using existing methane monitoring instrumentation it is difficult to fully quantify its emission rates and location of sources and sinks. Thus technologies that enable remote sensing of natural and anthropogenic methane emissions are needed for accurate assessment of sources and sinks of this very important greenhouse gas. We proposed a new remote sensing technology that is capable of atmospheric CH4 monitoring and will provide significant improvements over the current state-of-the-art. This project was a collaborative effort between an NSF Engineering Research Center MIRTHE (Mid-infrared Technologies four Health and the Environment) and Physical Sciences Inc., a company that has a long record of successful development and commercialization of laser based remote sensing systems. In this collaborative project a new cryogen-free remote spectroscopic chemical sensing technology has been developed. This project has focused on methane monitoring but the developed technology can be applied to a large number of chemical sensing applications in environmental studies, industrial emission monitoring and security. The main research goal of the project was the development of a remote sensor system prototype based on chirped laser dispersion spectroscopy (CLaDS) for detection of methane gas at atmospheric levels. The project was divided into multiple tasks focused on laboratory performance tests and calibration, cross-comparison with existing methane sensing systems, and field tests of the developed sensing system. All planned tasks have been successfully completed, which resulted in a transportable prototype remote sensing technology (see Fig. 1) operating at the wavelength of 1.6mm and capable of methane detection with 1.65 ppmv-m/Hz1/2 precision (optical path and detection bandwidth normalized). The technology is modular and can be customized for detection of other gases of environmental and industrial importance. The technology shows very good potential to enter the commercialization phase. The system has been successfully deployed in the field to perform measurements of natural methane emissions (see Fig. 2). The developed instrument was able to operate autonomously with specifications similar to the performance observed in laboratory conditions. The collected data were cross-compared with two different methane sensing technologies at the measurement site (RMLDTM from Physical Sciences Inc. and chamber based point methane sensors operated by University of New Hampshire) and excellent agreement was found. The project provided one PhD student, one MS student and two post-docs with a hands-on research experience in the field of optics and spectroscopy as well as it provided them with training in mentoring of undergraduate students involved (including MIRTHE REU students). In general a sensitive, fast, in-situ molecular remote detection has a large number of applications in environmental studies, industrial emission monitoring and security. Therefore the outcomes of this project in a form of a new sensing technology achieved through a well-integrated research and education program provided a comprehensive training for the new generation of scientists and engineers, who will have a strong impact on the society wellbeing in the future.
