High-Performance Fourier Transform Infrared Spectrometer: A Versatile Modular Interdisciplinary Instrument in the Regional Atmospheric Profiling Center for Discovery David A. Bowdle University of Alabama in Huntsville NASA/UAH Atmospheric Science "Brown Bag" Seminar December 4, 2002

FTIR Theory FTIR Instrument  Optical Layout  Basic Capabilities FTIR Science  Planned Use in RAPCD  Potential Interdisciplinary Projects  Brain-storming OUTLINE A  OR

FTIR THEORY A  OR Let spectrum 1 represent a gas sample or a suspended aerosol in the atmosphere or in a laboratory chamber, or an aerosol deposit on a substrate. Let spectrum 0 represent a blank. Photo- counts Source Radiance Receiver Area and Solid Angle Optical Efficiency Gain, Spectral Resolution, Intergration Time Transmission Extinction Units Instrument Artifacts Concentration In situ Mass Extinction Efficiency Optical Distortion Effective Length Correction Reduce By Design

NICOLET NEXUS 870 FTIR – EXTERNAL VIEW External Experiment Data Interface Left External Beam Port Dual Detector Compartment Main Sample Compartment Dual Source Compartment Interferometer Compartment A  OR

NICOLET NEXUS 870 FTIR – INTERNAL VIEW Main Sample Compartment (KBr Windows) DTGS Detector (MIR) InGaAs Detector (NIR) Motorized Path Selection Mirrors Data & Purge Ports Power Supply Signal Processor Michelson Interferometer) Internal Source Compartment A  OR

NICOLET NEXUS 870 FTIR – TOP VIEW Incandescent Source (VIS/NIR) Globar Source (MIR) Condensing Mirror (Source) Motorized Aperture Wheel Condensing Mirror (Sample) Motorized Collimating Mirror Michelson Interferometer) HeNe Laser A  OR

Left External Beam External Source Beam NICOLET NEXUS 870 FTIR – OPTICAL PATH Left External Beam A  OR

NICOLET NEXUS 870 FTIR – INTERFEROMETER HeNe Laser Moving Mirror Drive Piezo-Electric Dynamic Alignment Fixed Mirror Laser Pickoff Mirror Dynamic Alignment Phase Detectors KBr Beam Splitter Extended Range A  OR

NICOLET FTIR CAPABILITIES A  OR Linear scan  Scan speeds up to ~50 Hz  Spectral resolution as fine as ~0.125 cm -1  Spectral range from ,000 cm -1  Automated experiment setup including alignment; recognition of key components and accessories; selection of source, detector, and sample chamber; diagnostics; etc.  Easily adaptable to custom attachments Step scan  Amplitude modulation Chopper, with lock-in-amplifier Repeatable sample phenomena Slow (ms) to ultra-fast (  s) processes  Phase modulation Dithering of fixed mirror Analysis of thin layers

FTIR OPERATION A  OR Attend demonstration of Nicolet Nexus 870 FTIR in NSSTC Room 2014 after presentation and brainstorming session

NICOLET NEXUS FTIR - REMOTE SENSING STATION A  OR Solar Tracker Chimney Horizon Scanner Chimney Optical Curtains Optical Bench Cooling Water & Drain Utility Buss Bar 110, 208 1/Ph, 2083/Ph Air, Vacuum, Nitrogen Data Ports, Light Switch Dimming Incandescents Not Shown: Dimming Fluorescents Casework HEPA Filters

AEROSOL  ICROPHYSICS AND RADIOMETRY LAB A  OR

AEROSOL  ICROPHYSICS AND RADIOMETRY LAB A  OR

RAPCD CHIMNEY INSPECTION Mike Newchurch goes to great lengths to make sure RAPCD works Jay Leko interviews for a RAPCD research position A  OR

PLANNED USE IN RAPCD Composition and Concentration of Particles and Trace Gases Atmospheric Chemistry Measurements  Column optical depth, using multi-spectral Langley plots from a roof-mounted solar tracker with dithered pointing  Horizontal optical thickness, using one-way or two-way transmission with a roof-mounted alt-azimuth scanner  Cloud initiation, cloud particle phase, fog chemistry  Aspirated sample analysis, using bottles, filters, impactors  Size-dependent composition of airborne mineral dust  Deployment in RAPCD mobile van A  OR

PLANNED USE IN RAPCD Composition and Concentration of Particles and Trace Gases Atmospheric Chemistry Simulations  Artificial aerosols suspended in air, deposited on substrates  Heterogeneous chemical reactions, chemical kinetics Calibration/Validation of Atmospheric Sensors and Models  Backscatter enhancement spectra from particle coatings  Composition of calibration particles for lidar backscatter  Optical distortion in particulate deposits on substrates  Scattering from non-spherical particles (e.g., pollen grains)  Polarimetry in transmission, forward scatter, backscatter A  OR

INTERDISCIPLINARY PROJECTS  Satellite remote sensing validation  Precipitation chemistry (remote or aspirated)  Spectral backscatter from simulated river surfaces  Optical emissions and chemical byproducts of lightning  Spectroscopy of simulated interstellar dust grains  Solar spectroscopy and solar variability  Nano-technology, bioaerosol detection  Brief brain-storming session after seminar dismisses A  OR

SUMMARY AND CONCLUSIONS  New high-performance FTIR obtained for RAPCD  Provides versatile tool for atmospheric chemistry research, in both ambient and simulated environments  Initial installation in RAPCD aerosol lab expected in January. Rooftop scanners to be acquired in future proposals.  Offers opportunity for interdisciplinary research ventures by adding modular commercial or in-house accessories A  OR