Formaldehyde (HCHO) has been a key target for NASA’s upper atmospheric and tropospheric chemistry research programs because of its role in various atmospheric oxidative processes involving greenhouse gases. Additionally, there has been recent interest in detecting HCHO in the Martian atmosphere as it serves as a marker for methane concentration. To this end, we propose to build and test a high-power 353 nm fiber laser transmitter based on large mode area fiber technology that will serve as an excitation source for range-resolved laser-induced fluorescence (LIF) measurements of formaldehyde.

Improving our understanding of the coupled chemistry-climate system is a key goal of NASA Earth Science. HCHO plays an important role atmospheric photochemistry involving the lifetime of greenhouse gases such as methane, ozone, and secondary organic aerosol production. Currently, atmospheric HCHO concentrations are measured by passive satellite sensors such as the Ozone Monitoring Instrument (OMI) and the TROPOspheric Monitoring Instrument (TROPOMI) measure HCHO slant column concentrations, but these instruments suffer from atmospheric scattering effects, weak HCHO absorption, and model-derived concentration profiles; these effects serve to limit the accuracy of these passive measurements. Successful development of the proposed 353 nm fiber laser will enable active remote sensing instruments using the fluorescent properties of HCHO to be developed that can make range-resolved measurements of atmospheric formaldehyde concentrations.